WO2001035839A2

WO2001035839A2 - Endarterectomy apparatus and method

Info

Publication number: WO2001035839A2
Application number: PCT/US2000/031615
Authority: WO
Inventors: Steve G. Baker; David H. Deaton; James J. Leary
Original assignee: Acumen Vascular, Inc.
Priority date: 1999-11-16
Filing date: 2000-11-16
Publication date: 2001-05-25
Also published as: WO2001035839A3; AU1772901A

Abstract

Improved apparatus and methods are described for performing endarterectomy remotely via intraluminal techniques. A flexible blade dissector has a curved, diamond-shaped flexible dissecting blade mounted on a catheter shaft. The distal edge of the flexible dissecting blade is configured to form a dissecting edge for separating an atheromatous plaque from the medial layer of an artery wall. The flexible blade dissector may incorporate a steering mechanism to direct the flexible dissecting blade along a preferred path within the arterial wall. The endarterectomy method is performed by making an incision into an artery wall and initiating a plane of separation between an atherosclerotic plaque and the medial layer of the artery wall, inserting the flexible blade dissector into the plane of separation and advancing the flexible dissecting blade to longitudinally extend the plane of separation. Optionally, a second flexible blade dissector with a wider dissecting blade may be inserted coaxially over the catheter shaft of the first flexible blade dissector and advanced to laterally expand the plane of separation. Once the plaque has been freed from the entire inner circumference of the arterial lumen, the plane of separation is terminated on the distal and proximal ends, and the plaque is removed from the arterial lumen.

Description

ENDARTERECTOMY APPARATUS AND METHOD

FIELD OF THE INVENTION

The present invention relates to surgical apparatus and methods. In particular, it relates to apparatus and methods for treatment of blockages in body passages, particularly for removal of atherosclerotic plaques from arteries via endarterectomy.

BACKGROUND OF THE INVENTION

Atherosclerosis is a progressive disease of the cardiovascular system characterized by a buildup of plaques within a patient's arteries, resulting in a stenosis (narrowing) or occlusion (blockage) of the arterial lumen. Atherosclerotic plaques are generally deposits of cholesterol and lipids within the intimal layer of the arteries, which may also become calcified over time. When the arterial lumen becomes too narrow, it can cause ischemia in the tissue and organs downstream of the blockage, resulting in pain (angina or claudication), dysfunction, necrosis and even death, depending on what organ systems are involved.

One of the common treatments for atherosclerosis is arterial bypass grafting, wherein an artificial or biological conduit or bypass graft is used to reroute blood flow around the blockage. This is a complex surgical procedure, sometimes involving considerable morbidity and a risk of eventual occlusion of the bypass graft as the underlying disease progresses. Other treatments include dilatation or angioplasty, in which a tapered dilator or a balloon catheter is used to push the plaque aside to open the arterial lumen, and atherectomy, which involves cutting and removal or comminution of the plaque material. Stenting is an adjunct to angioplasty and atherectomy in which a vascular endoprosthesis (a stent) is implanted in the artery to maintain an open lumen after dilating or debulking the lesion. These approaches are most effective for discrete, focal lesions and are less effective for long lesions and diffuse atherosclerotic disease. Clinical data also indicate that there is a significant percentage of restenosis after both angioplasty and atherectomy, even with stenting. Furthermore, angioplasty, atherectomy and stents are ineffective in arteries with total occlusions. However, because angioplasty and atherectomy can be performed using minimally invasive catheter techniques, these approaches are sometimes favored for treating lesions that are difficult to access surgically, for example in coronary artery disease.

For atherosclerotic lesions in arteries that are surgically accessible, particularly long or diffuse lesions, endarterectomy is considered to be a more definitive treatment than angioplasty or atherectomy and, with advanced techniques, offers lower morbidity than surgical bypass. Endarterectomy involves surgically opening the artery, removing plaque from the interior of the artery and surgically closing the artery. To remove plaque, a plane of separation is established between the plaque and the medial layer of the artery. The plaque is dissected away from the media along the plane of separation and removed, along with the endothelial layer of the artery. If the plaque is long and extends beyond the portion of the artery to be treated, the plane of separation is smoothly terminated on its proximal and distal ends to prevent further dissection of the arterial wall. Endarterectomy has the advantage that it preserves the original arterial conduit, maintaining the original flow geometry and topology and offering a hemocompatible arterial lining with proven long-term patency. Endarterectomy actually removes the plaque rather than simply pushing it aside or routing blood flow around it. In addition, endarterectomy can also be used to effectively treat totally occluded arteries.

As an adjunct, a stent or stent graft may be implanted to re-line the vessel after endarterectomy. Alternatively or in addition, stents may be used in the transition zones at the ends of the treated portion of the artery to prevent further dissection of the arterial wall. The stent or stent graft will prevent abrupt reclosure and may reduce the occurrence of restenosis in the long term. Other adjunctive treatments may be used to reduce the chance of intimal hyperplasia or long term restenosis. These treatments include radiation therapy (e.g. brachytherapy), therapeutic ultrasound, local or systemic drugs and gene therapy.

Standard open endarterectomy has a disadvantage in that a long incision is required to expose and open the entire length of the arterial section to be treated. In order to reduce the size of the incision needed, and the concomitant morbidity involved, methods have been devised for performing endarterectomy less invasively. These methods generally involve making a series of small incisions at intervals along the length of the artery and using elongated instruments to separate and remove the plaques from the arterial lumen between the incisions, while keeping the arteries relatively intact. Examples of instruments for facilitating less invasive endarterectomy can be found in U.S. patent 4,290,427 to Albert K. Chin and Thomas J. Fogarty, U.S. patent 5,843,102 to Menno Kalmann and Franciscus Laurens Moll, and U.S. design patent D307323 to Timothy M. Scanlan, which are hereby incoφorated in their entirety. Less invasive or remote endarterectomy has the advantages of standard endarterectomy and the additional advantages that it produces less trauma and morbidity than either standard endarterectomy or bypass surgery and, with the appropriate techniques, can entirely avoid the difficulty of end-to-side or end-to-end anastomoses. Although less invasive endarterectomy has a great many advantages, the current instruments and methods have limitations in terms of the length of the artery that can be treated through a single incision. They are also limited in the amount of variation allowable in the arterial wall that can be treated. Variations in the arterial wall that can interfere with treatment can be caused by tortuosity of the arteries and by changes in diameter of the artery over its length, as well as other factors. These limitations are closely related, since the longer the section of the artery to be treated, the more likely it is to have such variations in the arterial wall. While the prior endarterectomy apparatus and methods represent a significant step forward in the treatment of atherosclerosis, continued research has been directed toward further improvements in the technology for performing endarterectomy. In particular, research has been directed toward devising instruments and methods that facilitate performing endarterectomy over longer lengths of artery, through fewer and smaller incisions and, ideally, to allow dissection, termination and removal of atherosclerotic plaques over long lengths of artery through a single incision. In furtherance of this goal, this research has also been directed toward devising apparatus and methods that will facilitate effective endarterectomy despite variations in the arterial wall due to tortuosity or diameter changes.

SUMMARY OF THE INVENTION

In keeping with the foregoing discussion, the present invention takes the form of improved apparatus and methods for performing endarterectomy remotely via intraluminal techniques. The endarterectomy apparatus of the present invention takes the form of a flexible blade dissector having a flexible dissecting blade mounted at the distal end of an elongated catheter shaft. In a preferred embodiment, the flexible dissecting blade is approximately diamond shaped, having approximately triangular shaped lateral wings arranged symmetrically on the left and right side of the catheter shaft. The distal edge of the flexible dissecting blade is configured as a dissecting edge capable of initiating and extending a plane of dissection between an atheromatous plaque and the medial layer of the artery without cutting into either the plaque or the tissue of the medial layer. The distal edge of the flexible dissecting blade may be sharpened to form a sharp dissecting edge or, alternatively, it may be rounded to form a blunt dissecting edge. The flexible dissecting blade is constructed to have differential stiffness such that the lateral wings will readily bend around a central longitudinal axis, but will resist bending perpendicular to this axis. Stiffeners or other structures may be incorporated into the flexible dissecting blade to enhance the differential stiffness. Preferably, the flexible dissecting blade is made with an initial curve, which helps it to conform to the curvature of the arterial wall. The flexible blade dissector may incorporate a steering mechanism to direct the flexible dissecting blade along a preferred path within the arterial wall.

The endarterectomy method of the present invention is practiced by making an incision into an artery wall and initiating a plane of separation between an atherosclerotic plaque and the medial layer of the artery wall, inserting the flexible blade dissector into the plane of separation and advancing the flexible dissecting blade to longitudinally extend the plane of separation. Optionally, a second flexible blade dissector may be inserted into the plane of separation coaxially over the catheter shaft of the first device and advanced to laterally expand the plane of separation. Once the plaque has been freed from the entire inner circumference of the arterial lumen, the plane of separation is terminated on the distal and proximal ends if necessary, and the plaque is removed from the arterial lumen, using known techniques.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS 1, 2 and 3 illustrate a first embodiment of a flexible blade dissector for performing remote endarterectomy via intraluminal techniques. FIG 1 shows a front view of the flexible blade dissector, FIG 2 shows a distal end view and FIG 3 shows a back view of the flexible blade dissector.

FIGS 4 A, 4B and 4C show the flexible blade dissector of FIGS 1 and 2 in use for treating an artery using remote endarterectomy techniques. FIGS 5 and 6 illustrate a coaxial system of flexible blade dissectors for performing remote endarterectomy via intraluminal techniques.

FIGS 7, 8 and 9 show a flexible blade dissector having a flexible dissecting blade with internal longitudinal stiffeners to enhance the differential stiffness. FIG 7 is a front view, FIG 8 is a distal end view and FIG 9 is a side view of a distal portion of the flexible blade dissector.

FIGS 10 and 11 show another flexible blade dissector having a flexible dissecting blade with longitudinal grooves to enhance the differential stiffness. FIG 10 is a front view and FIG 11 is a distal end view of a distal portion of the flexible blade dissector.

FIGS 12 and 13 show another flexible blade dissector having a flexible dissecting blade with an internal stiffener at the leading edge to enhance the differential stiffness. FIG 12 is a front view and FIG 13 is a distal end view of a distal portion of the flexible blade dissector.

FIGS 14, 15, 16, 17 and 18 show another flexible blade dissector illustrating an alternate geometry for the flexible dissecting blade. FIG 14 is a front view, FIG 15 is a distal end view, FIG 16 is a side view and FIG 17 is a perspective view of a distal portion of the flexible blade dissector.

FIGS 18-23 show the application of neck-based steering for controlling the radial position of the flexible dissecting blade with respect to the arterial wall.

FIGS 24-29 show the application of neck-based steering for controlling the lateral position of the flexible dissecting blade with respect to the arterial wall.

FIG 30 shows an embodiment of the flexible blade dissector having neck-based steering provided by a rotatable external guide catheter for controlling the direction of the catheter shaft.

FIG 31 shows the application of nose-based steering for controlling the radial position and lateral position of the flexible dissecting blade with respect to the arterial wall.

FIG 32 shows an embodiment of the flexible blade dissector having nose-based steering provided by a rotatable internal steering tube within the catheter shaft.

FIGS 33-36 show the application of wing-based steering for controlling the radial position and the lateral position of the flexible dissecting blade with respect to the arterial wall.

FIGS 37-38 show an embodiment of the flexible blade dissector having wing-based steering provided by a pull wires connected to the wings of the flexible dissecting blade.

FIGS 39-42 show an embodiment of the flexible blade dissector having wing-based steering provided by inflatable chambers within the wings of the flexible dissecting blade. FIG 43 shows a flexible blade endarterectomy catheter with a bulb at the distal catheter tip.

FIG 44 shows a flexible blade endarterectomy catheter with a bulb between the catheter tip and the flexible dissecting wings. FIG 45 shows a flexible blade endarterectomy catheter with a balloon.

FIG 46 shows a flexible blade endarterectomy catheter with a balloon distal to a bulb.

FIG 47 shows a flexible blade endarterectomy catheter with a balloon concentrically over a bulb.

FIG 48 shows a flexible blade endarterectomy catheter with a balloon between a bulb and the dissecting wings.

FIG 49 shows an endarterectomy catheter with an expandable braid inside a membrane.

FIG 50 shows a split ring stripper.

FIG 51 shows a split ring stripper wherein one end of the ring telescopes inside the other end.

FIG 52 shows a wire loop supported by a tube and a support rod surrounding a plaque.

FIG 53a shows a distal end view of a first catheter and a second catheter holding a wire loop around a plaque.

FIG 53b shows a side view of the first catheter and a second catheter of FIG 53a. FIG 54 shows a groove for holding a wire in a catheter.

FIG 55 shows a radially expandable ring formed by short segments connected by elastic or wire.

FIG 56 shows a side view of a tool with filament loops forming "flower petals" at leading edge of tool. FIG 57 shows an end view of a tool with filament loops forming "flower petals" at leading edge of tool.

FIG 58 shows individual filament loops "flower petals" each covered by a thin sheet.

FIG 59a shows a side view of filament loops "flower petals" all covered by a thin outer membrane. FIG 59b shows a distal end view of filament loops "flower petals" of FIG 59a.

FIG 60 shows a tool with a dissecting blade in the dissection plane and a shaft over a guide wire inside the arterial lumen.

FIG 61 shows a tool with a two dissecting blades in the dissection plane and a shaft over a guide wire inside the arterial lumen. FIG 62 shows two dissector catheters linked by a U shaped guide wire.

FIG 63a shows a distal end view of a U shaped guide wire that lies flat in a plane.

FIG 63b shows a side view of the U shaped guide wire of FIG 63a.

FIG 64a shows a distal end view of a U shaped guide wire that curves in two directions. FIG 64b shows a distal end view of the U shaped guide wire of FIG 64a performing an endarterectomy.

FIG 64c shows a side view of the U shaped guide wire of FIG 64a.

FIG 65a shows two U shaped guide wires used to connect multiple catheters. FIG 65b shows two U shaped guide wires used with a single catheter.

FIG 66 shows U shaped guide wires and catheters daisy chained to form a complete closed perimeter around the dissection plane.

FIG 67 shows two U shaped guide wires linking three dissecting endarterectomy catheters between an inner artery with plaque and an outer artery wall. FIG 68 shows two U shaped guide wires linking three dissecting endarterectomy catheters around an inner artery with plaque. For clarity, the outer artery wall is not shown.

FIG 69a shows a side view of a first catheter with a guide wire attached to a wingtip, and a second catheter with a guide wire lumen in a wingtip. The guide wire of the first catheter is guiding the second catheter. FIG 69b shows a distal end view of the first and second catheters of FIG 69a performing an endarterectomy.

FIG 70a shows a side view of a first catheter with two guide wires attached to the catheter wingtips, and a second catheter with two guide wire lumens in the second catheter wingtips. The guide wires of the first catheter are guiding the second catheter. FIG 70b shows a distal end view of the first and second catheters of FIG 70a performing an endarterectomy.

FIG 71 shows a side view of three catheters linked together in a "daisy chain". Each catheter has a guide wire attached to a dissector blade that may guide another catheter. The catheters nest together. FIG 72 shows an end view of three catheters daisy chained to form a complete closed perimeter around the dissection plane.

FIG 73a shows a distal end view of two endarterectomy catheters with coaxial shafts.

FIG 73b shows a side view of the two endarterectomy catheters of FIG 73 a.

FIG 74a shows a side view of two endarterectomy catheters with coaxial shafts and wings extending in opposite directions.

FIG 74b shows a distal end view of the two endarterectomy catheters of FIG 74a.

FIG 75 shows a first catheter, a second catheter, and a third catheter. The second catheter has a dissecting wingtip with a lumen. The lumen slides over the shaft of the first catheter for guidance and positioning. FIG 76a shows a side view of a first catheter and a second catheter. The second catheter has a dissecting wingtip with a T shaped wingtip. The T shaped wingtip slides into a groove in the shaft of the first catheter for guidance and positioning.

FIG 76b shows a distal end view of the first and second catheters of FIG 34a. FIG 77a shows a side view of a flexible ring on a shaft placed in a large vessel. The ring can flex and rotate relative to the shaft in order to accommodate variations in artery size, shape, or angulation.

FIG 77b shows a distal end view of the catheter of FIG 77a. FIG 77c shows a side view of the catheter of FIG 77a placed in a small vessel.

FIG 77d shows a distal end view of the catheter of FIG 77c.

FIG 78a shows a side view of a flexible ring with a wavy, undulating (e.g. sinuous, zigzag) shape placed in a large vessel.

FIG 78b shows a distal end view of the catheter of FIG 78a performing an endarterectomy.

FIG 78c shows a side view of the catheter of FIG 78a placed in a small vessel.

FIG 78d shows a distal end view of the catheter of FIG 78c performing an endarterectomy.

FIG 79 shows a flexible ring of bent wire on a shaft. FIG 80 shows a flexible bent wire ring with an inward bend on the leading edge, on a shaft

FIG 81 shows a flexible ring of varying width or thickness.

FIG 82a shows an oblique view of a dissecting catheter with wings connected by a flexible segment to form a variable diameter ring. FIG 82b shows a side view of the catheter of FIG 82a.

FIG 82c shows a distal end view of the catheter of FIG 82a performing an endarterectomy.

FIG 83a shows a cross section of a dissecting catheter with flexible loops of adjustable size. FIG 83b shows a side view of the catheter of FIG 83a.

FIG 83c shows a distal end view of the catheter of FIG 83a.

FIGS 84a-84f show dissecting catheters with two or three flexible loops.

FIG 85a shows a cross section of a dissecting catheter with covered flexible loops and a handle for adjusting loop size. FIG 85b shows a distal end view of the catheter of FIG 85a.

FIG 86 shows a partial cross sectional view of a dissecting catheter with a slider in the handle to adjust loop length.

FIG 87 shows a partially disassembled view of a dissecting catheter with a slider and handle to adjust loop length. FIGS 88a-88c illustrate advancing the handle slider to extend the loops.

FIG 89 shows a dissecting catheter with flexible loops and an anti-buckling tube that slides inside a shaft.

FIGS 90a-90b shows a dissecting catheter with a flexible loop made from a filament of tapered diameter. FIG 91 shows a side view of a dissecting catheter with two flexible elements and a tubular control member.

FIG 92 shows a top view of a dissecting catheter with two flexible elements and a tubular control member in an artery with plaque. FIG 93a shows a side view of a dissecting catheter with two flexible elements and a cylindrical control member.

FIG 93b shows a distal end view of the catheter of FIG 93a.

FIG 94 shows a distal end view of an endarterectomy catheter with three guide wire lumens, one in the shaft and one in each wingtip. FIG 95 shows an endarterectomy catheter being advanced or retracted over three guide wires.

FIG 96 shows an endarterectomy catheter with two guide wire lumens, one in each wingtip.

FIG 97 shows a side view of an endarterectomy catheter with two guide wire lumens, one in the shaft and one in a wingtip.

FIG 98a shows an endarterectomy catheter with a dissector blade with two wingtips and two shafts with lumens for guide wires.

FIG 98b shows a distal end view of the catheter of FIG 98a.

FIG 99 shows a prototype endarterectomy catheter with a dissector blade with two wingtips and two shafts with lumens for guide wires.

FIG 100 shows an endarterectomy catheter spreading two guide wires apart to create a dissection between a plaque and an outer artery wall. A third guide wire maintains access to the true lumen.

FIG 101 shows a three lumen catheter being advanced over a first guide wire. FIG 102a is an end view of a guide wire being advanced to create a dissection plane.

FIG 102b is a side view of a guide wire being advanced to create a dissection plane.

FIG 103 a is an end view of a two lumen catheter being advanced over the first guide wire.

FIG 103b is a side view of a two lumen catheter being advanced over the first guide wire.

FIG 104a is an end view of a second guide wire being advanced through the second lumen of the catheter.

FIG 104b is a side view of a second guide wire being advanced through the second lumen of the catheter. FIG 105a is an end view of the catheter being removed, and the two guide wires being kept in place.

FIG 105b is a side view of the catheter being removed, and the two guide wires being kept in place. FIG 106a is an end view of an endarterectomy catheter being advanced over the two guide wires.

FIG 106b is a side view of an endarterectomy catheter being advanced over the two guide wires. FIG 107a is an end view of the catheter being removed, and the two guide wires being kept in place.

FIG 107b is a side view of the catheter being removed, and the two guide wires being kept in place.

FIG 108a is an end view of the catheter dissecting the remaining portion of the circumference, creating a complete circumferential dissection of the plaque from the artery wall.

FIG 108b is a side view of the catheter dissecting the remaining portion of the circumference, creating a complete circumferential dissection of the plaque from the artery wall. FIGS 109a- 109d show an endarterectomy catheter with its wing being flexed to the opposite circumferential curvature to move the catheter to the opposite side of the plaque without exchanging guide wires to opposite wing tips.

FIGS 110a- 110b show a dissecting catheter with an adjustable width blade.

FIG 111 shows a catheter shaft moving towards the inner side of a bend when retracted in an artery without support.

FIG 112 shows the use of an internal support to reduce undesired catheter movement.

FIG 113 shows engaging means (e.g. hooks, barbs, MEMS bristles, mica flakes) to engage the plaque during closed endarterectomy.

FIG 114 shows engaging means angled retrograde to allow a catheter to slide freely over the plaque when advancing the catheter.

FIG 115 shows retrograde angled engaging means gripping the plaque when retracting the catheter.

FIGS 116a- 116b show a catheter with engaging means that are retractable or erectile.

FIGS 117a- 117b show MEMS engaging means. FIGS 118a- 118b show a surface that may be moved to expose the engaging means and engage the plaque.

FIG 119 shows a balloon pushing plaque radially out against a ring to cut the plaque.

FIG 120 shows a ring stripper advancing distally to push plaque against a balloon to cut the plaque. FIGS 121 a- 121c show loops attached to two catheter shafts for gripping plaque.

FIGS 122a- 122b show a U shaped guide wire used with a two lumen catheter for dissecting plaque.

FIG 123 shows an endarterectomy catheter with variable width loops having guidewire lumens on the loops. FIG 124 shows a capture bag device for collecting the plaque. FIG 125 shows the capture bag device of FIG 124 in use.

FIG 126 shows a capture bag device with a draw string closure to capture the plaque. FIGS 127a- 127b show a capture bag device with a purse string closure to capture the plaque.

FIG 128 shows a capture bag device with a twisting closure to capture the plaque. FIG 129 shows a capture bag device with accordion folds. FIGS 130-131 show a braided capture device for collecting the plaque. FIGS 132a- 132b show a plaque removal tool with an elongated wing with engaging means.

FIGS 133a-133b show a plaque collection bag or tube with internal engaging means. FIG 134 shows a variable stiffness shaft assembly.

DETAILED DESCRIPTION OF THE INVENTION In keeping with the foregoing discussion, the present invention takes the form of improved apparatus and methods for performing endarterectomy remotely via intraluminal techniques. FIGS 1, 2 and 3 illustrate a first embodiment of a flexible blade dissector 100 for performing remote endarterectomy via intraluminal techniques. FIG 1 shows a front view of the flexible blade dissector 100, FIG 2 shows a distal end view and FIG 3 shows a back view of the flexible blade dissector 100. The flexible blade dissector 100 has a flexible dissecting blade 102 mounted at the distal end of an elongated catheter shaft 104. The flexible dissecting blade 102 has a distal edge 106 and a proximal edge 108. The distal edge 106 is configured as a dissecting edge capable of initiating and extending a plane of dissection between an atheromatous plaque and the underlying media without cutting into either the plaque or the tissue of the medial layer. In one preferred embodiment, the distal edge 106 of the flexible dissecting blade 102 is sharpened to form a sharp dissecting edge for initiating and extending the plane of dissection. In another preferred embodiment, the distal edge 106 of the flexible dissecting blade 102 is rounded to form a blunt dissecting edge for initiating and extending the plane of dissection by blunt dissection. The proximal edge 108 of the flexible blade dissector 100 may be rounded and blunt.

Preferably, the elongated catheter shaft 104 is tubular in construction, having a guidewire lumen 110 that extends through the catheter shaft 104 and through the flexible blade dissector 100 to the distal edge 106. The guidewire lumen 110 is sized to provide a sliding fit over a guidewire, for example a standard .032, .035 or .038 inch diameter guidewire, a steerable guidewire or a specialized guidewire. Alternatively, the lumen 110 may be used for insertion of other instruments, such as an endoscope, a cutter, a snare, a grasper or other tools. The catheter shaft 104 is constructed to have sufficient column strength to advance the flexible blade dissector 100 along the plane of separation as the distal edge 106 dissects the plaque away from the media, while also having sufficient flexibility to follow the tortuosity of the arterial path. The catheter shaft 104, in this and each of the embodiments described herein, may be constructed of an extruded polymer or elastomer tube, a flexible metal tube or a composite construction, such as a braided wire reinforced polymer tube. The proximal end of the catheter shaft 104 is equipped with a fitting 122, such as a standard luer lock connector. If desired, the proximal end of the catheter shaft 104 may also be equipped with a hand grip or the like for improved handling and ergonomics. The length of the catheter shaft 104 is preferably between approximately 10 and 150 cm, more preferably from approximately 30 to 60 cm. The diameter of the catheter shaft 104 is preferably from approximately 1.5 to 3 mm. The flexible dissecting blade 102 is generally spatulate in shape and flexible to conform to the inner curvature of the arterial wall. In one particularly preferred embodiment, the flexible dissecting blade 102 is approximately diamond shaped, having approximately triangular shaped lateral wings 114, 116 arranged symmetrically on the left and right side of the catheter shaft 104. The thickness of the lateral wings 114, 116 tapers down laterally away from a central ridge 112 located where the guidewire lumen 110 passes through the flexible dissecting blade 102, as shown in the distal end view of FIG 2. The central ridge 112 of the flexible dissecting blade 102 is somewhat stiffer than the lateral wings 114, 116. This differential stiffness is further enhanced by the presence of a guidewire within the guidewire lumen 110. The differential stiffness of the flexible dissecting blade 102 may be further enhanced using any of the constructions described below in connection with FIGS 7-12. The differential stiffness gives the flexible dissecting blade 102 a preferential bending geometry so that the lateral wings 114, 116 will readily bend around a central axis defined by the guidewire lumen 110 and the central ridge 112, but the flexible dissecting blade 102 resists bending perpendicular to this axis. In order to encourage the preferential bending geometry, the flexible dissecting blade 102 may be given an initial curve, as shown. In this case, the central ridge 112 is preferably placed on the concave side 118 of the curve so that the convex side 120 of the flexible dissecting blade 102 will be smooth. The width of the flexible dissecting blade 102 is preferably from approximately 25% to 125% of the vessel circumference, more preferably from approximately 33% to 100% of the vessel circumference. The flexible blade dissector 100 is typically intended to be used in arteries with a circumference from approximately 12 to 45 mm, although the device could be scaled larger or smaller for use in other vessels.

The flexible dissecting blade 102, in this and each of the embodiments described herein, is preferably made of a flexible polymer or elastomer. Suitable materials include, but are not limited to, polyethylene, polypropylene, polyolefins, polyvinylchloride, polyamides (nylons), polyurethanes, silicones, and copolymers, alloys and reinforced composites thereof. In addition, the flexible dissecting blade 102 may be coated with a low friction or lubricious coating. Additionally, the flexible blade dissector 100 may include a steering mechanism, such as those described below in connection with FIGS 19-43, to control the direction of the flexible blade dissector 100 as it dissects a plaque from the wall of the artery.

FIGS 4 A, 4B and 4C show the flexible blade dissector 100 of FIGS 1 and 2 in use for treating an artery A using remote endarterectomy techniques. First, the artery A to the treated is surgically exposed and the arterial lumen L is opened, either by transecting the artery or making an arteriotomy incision in the wall of the artery. A plane of separation S is initiated between the atheromatous plaque P and the medial layer M by pinching the arterial wall and/or by blunt dissection using a dissecting instrument. Alternatively, in some circumstances it may be desirable to position the plane of separation S within the medial layer M or the adventitial layer or at the interface between the medial and adventitial layers of the artery A. A guidewire 124 is inserted into the plane of separation S, followed by the flexible dissecting blade 102 of the flexible blade dissector 100. The guidewire 124 helps to guide the flexible blade dissector 100 along the plane of separation S. The initial curvature of the flexible dissecting blade 102 aids in inserting the blade 102 into the plane of separation S. The guidewire 124 and the flexible dissecting blade 102 are advanced, either sequentially or simultaneously, to widen and extend the plane of separation. As the flexible blade dissector 100 is advanced, the distal edge 106 of flexible dissecting blade 102 dissects the atheromatous plaque A and the endothelial layer E away from the underlying medial layer M. The differential stiffness of the flexible dissecting blade 102 allows it to conform to the arterial wall by bending around the central axis defined by the guidewire lumen 110 and the central ridge 112, yet it resists bending perpendicular to this axis so that the distal edge 106 of the flexible dissecting blade 102 maintains the proper orientation for effectively dissecting the plaque P along the plane of separation S. The differential stiffness of the flexible dissecting blade 102 allows the flexible blade dissector 100 to be used in arteries of different diameter. The differential stiffness of the flexible dissecting blade 102 also allows it to conform to variations in the arterial wall due to tortuosity of the artery or changes in diameter of the artery over its length.

As an illustration of this principle, FIGS 4A, 4B and 4C show cross sections of the same flexible blade dissector 100 used in arteries of differing diameters or in different portions of the same artery. FIG 4 A shows the flexible blade dissector 100 in an artery with a diameter that closely matches the initial curvature of the flexible dissecting blade 102. The flexible dissecting blade 102 effectively removes the plaque P from approximately half of the inner circumference of the arterial lumen L at once. As the flexible blade dissector 100 advances within the artery A, the flexible dissecting blade 102 conforms to changes in the arterial wall due to tortuosity of the artery or changes in diameter of the artery over its length. For example, FIG 4B shows the same flexible blade dissector 100 in a smaller diameter artery where the flexible dissecting blade 102 effectively removes the plaque P from approximately two-thirds of the inner circumference of the arterial lumen L at once. FIG 4C shows the flexible blade dissector 100 in an even smaller diameter artery where the flexible dissecting blade 102 effectively removes the plaque P from the entire inner circumference of the arterial lumen L in a single pass. As an illustration of the capabilities of this endarterectomy technique, FIG 4C shows the flexible blade dissector 100 being used to remove a total occlusion from the artery. The lumen L of the artery A may be occluded with thrombus T and/or with atherosclerotic plaque P.

In small diameter arteries, the lateral wings 114, 116 may meet edge-to-edge, as shown in FIG 4C, or they may even overlap to accommodate to the inner diameter of the arterial lumen L. In situations, such as in FIGS 4A and 4B, where the flexible dissecting blade does not remove the plaque P from the entire inner circumference of the arterial lumen L in a single pass, the plaque P may be entirely removed by repeated passes of the flexible dissecting blade 102. Once the plaque P has been freed from the entire inner circumference of the arterial lumen L, the plane of separation is terminated on the distal and proximal ends if necessary, and the plaque is removed from the arterial lumen L, using known techniques. Optionally, the method may utilize a separate device, such as a Moll Ring Cutter (U.S. patent 5,843,102), to terminate the plane of separation. Other techniques for accomplishing these steps are described below.

In addition to the mechanical dissection by the distal edge 106 of the flexible dissecting blade 102, dissection of the plaque P can be enhanced by supplying a pressurized fluid, such as saline solution, through the guidewire lumen 110 or through an additional lumen provided in the catheter shaft 104. The pressurized fluid may be supplied at a constant flow rate or at a varying flow rate to create a pulsating jet of fluid directed at the separation plane between the plaque P and the medial layer M of the artery A.

FIGS 5 and 6 illustrate a coaxial system of flexible blade dissectors for performing remote endarterectomy via intraluminal techniques. A first flexible blade dissector 100, similar in construction to that shown in FIGS 1-3, has a first flexible dissecting blade 102 mounted on a first elongated catheter shaft 104. A second flexible blade dissector 150 has a second flexible dissecting blade 152 mounted on a second elongated catheter shaft 154. The second flexible blade dissector 150 is similar in construction to that shown in FIGS 1-3, except that the lumen 160 of the second catheter shaft 154 is large enough in diameter to insert the first catheter shaft 104 therethrough in a coaxial sliding relationship and the second flexible dissecting blade 152 is broader than the first flexible dissecting blade 102. In addition, optionally, the second flexible blade dissector 150 may be made with two distinct regions on the distal edge of the second flexible dissecting blade 152. A first, central region 156 adjacent to where the lumen 160 emerges is approximately as wide as the width of the first flexible dissecting blade 102 and is blunt and rounded. A second, outer region 158 is configured to form a dissecting edge. If desired, the coaxial system may have a third and a fourth flexible blade dissector. Additionally, one or both of the first and second flexible blade dissectors 100, 150 may include a steering mechanism, such as those described below in connection with FIGS 19-43, to control the direction of the flexible blade dissector 100 as it dissects a plaque from the wall of the artery. In use, the first flexible blade dissector 100 is advanced over a guidewire 124 so that the first flexible dissecting blade 102 creates a first, narrow channel along the plane of separation between the plaque and the medial layer. Next, the second flexible blade dissector 150 is advanced over the first catheter shaft 104 so that the outer region 158 of the second flexible dissecting blade 152 widens the channel. The central region 156 of the second flexible dissecting blade 152, being blunt and rounded, tends to follow the premade channel created by the first flexible dissecting blade 102. This helps to keep the second flexible blade dissector 150 on a predetermined path, while the second flexible dissecting blade 152 sequentially widens the channel. This process may be continued with any additional coaxial flexible blade dissectors, if necessary, until the plaque has been freed from the entire inner circumference of the arterial lumen.

Additional structure can be used to enhance the differential stiffness of the flexible blade dissector and its ability to conform to variations in the arterial wall due to tortuosity of the artery or changes in diameter of the artery over its length. FIGS 7, 8 and 9 show a flexible blade dissector 200 having a flexible dissecting blade 202 with internal longitudinal stiffeners 204 to enhance the differential stiffness. FIG 7 is a front view, FIG 8 is a distal end view and FIG 9 is a side view of a distal portion of the flexible blade dissector 200. The flexible dissecting blade 202 is made of a highly flexible polymer or elastomer, for example a low durometer PEBAX polyamide elastomer resin (ATOCHEM SA, France). Embedded within the flexible dissecting blade 202 are a multiplicity of internal longitudinal stiffeners 204, shown as hidden lines in FIGS 7 and 9. The internal longitudinal stiffeners 204 may be made of metal wire, such as stainless steel or a nickel-titanium alloy, or a stiff fiber, such as glass fiber, carbon fiber or a rigid polymer. The internal longitudinal stiffeners 204 are arranged roughly parallel to the central axis defined by the guidewire lumen 210 of the flexible blade dissector 200. The internal longitudinal stiffeners 204 may run substantially the full length of the flexible dissecting blade 202 from the distal edge 206 to the proximal edge 208.

Alternatively, the internal longitudinal stiffeners 204 may comprise a multiplicity of short wires or fibers arranged in a pattern that enhances the differential stiffness of the flexible dissecting blade 202. The arrangement of the internal longitudinal stiffeners 204 enhances the differential stiffness of the flexible dissecting blade 202, allowing it to bend around the central axis defined by the guidewire lumen 210, but resisting bending perpendicular to the central axis.

FIGS 10 and 11 show another flexible blade dissector 250 having a flexible dissecting blade 252 with longitudinal grooves 254 to enhance the differential stiffness. FIG 10 is a front view and FIG 11 is a distal end view of a distal portion of the flexible blade dissector 250. The flexible dissecting blade 252 is made of a flexible polymer or elastomer, for example a PEBAX polyamide elastomer resin. Formed in the surface of the flexible dissecting blade 252 are a multiplicity of longitudinal grooves 254. The longitudinal grooves 254 may run substantially the full length of the flexible dissecting blade 252 from the distal edge 256 to the proximal edge 258, as shown, or a multiplicity of shorter grooves may be arranged in a pattern that enhances the differential stiffness of the flexible dissecting blade 252. The longitudinal grooves 254 may be formed in the convex surface 264 or the concave surface 266 of the flexible dissecting blade 252 or in both surfaces. The flexible dissecting blade 252 between the longitudinal grooves 254 forms a multiplicity of longitudinal ribs 262 that enhance the longitudinal stiffness, while the longitudinal grooves 254 enhance the lateral flexibility. This arrangement enhances the differential stiffness of the flexible dissecting blade 252, allowing it to bend around the central axis defined by the guidewire lumen 260, but resisting bending perpendicular to the central axis. In an alternate construction method, the alternating longitudinal grooves 254 and longitudinal ribs 262 may be formed by laminating separate longitudinal ribs 262 onto a thin, flexible dissecting blade 252 to enhance the differential stiffness. If desired, the longitudinal ribs 262 and the flexible dissecting blade 252 may be made of different materials to further enhance the differential stiffness. With either construction method, the differential stiffness keeps the distal edge 256 of the flexible dissecting blade 252 in the proper orientation for dissecting the plaque away from the underlying medial layer, while it allows the flexible dissecting blade 252 to flex laterally in order to adjust to the internal diameter of the arterial lumen.

Additionally, the longitudinal grooves 254 may be filled with a softer material than the flexible dissecting blade 252 is made from to enhance the differential stiffness, while presenting a smooth outer surface on both the convex surface 264 and the concave surface 266 of the flexible dissecting blade 252. Alternatively, the longitudinal grooves 254 may covered over with an outer skin (not shown) to create voids within the flexible dissecting blade 252 to enhance the differential stiffness, or voids may be molded into the flexible dissecting blade 252 to enhance the differential stiffness.

FIGS 12 and 13 show another flexible blade dissector 300 having a flexible dissecting blade 302 with an internal stiffener 314 at the leading edge to enhance the differential stiffness. FIG 12 is a front view and FIG 13 is a distal end view of a distal portion of the flexible blade dissector 300. The flexible dissecting blade 302 is made of a flexible polymer or elastomer, for example a PEBAX polyamide elastomer resin. Embedded in the flexible dissecting blade 302, close to the distal edge 306, is an internal stiffener 314. The internal stiffener 314 may be made in one piece or in two pieces and is preferably attached to the catheter shaft 304 so that pushing force is transmitted from the catheter shaft 304 directly to the internal stiffener 314. The internal stiffener 314 maybe made of a metal, such as stainless steel or a nickel-titanium alloy, a rigid polymer, or a stiff fabric, such as a glass fiber or carbon fiber fabric. The internal stiffener 314 has a thickness R and a width Z, measured parallel with the central axis defined by the guidewire lumen 310, and a length measured perpendicular to the central axis. Preferably, the length of the internal stiffener 314 is substantially equal to the width of the flexible dissecting blade 302 and closely conforms to the distal edge 306, which in this exemplary embodiment approximates a semicircular arc. If desired, the width Z may taper along the length of the internal stiffener 314, as illustrated by the difference between Zl and Z2 in FIG 12, making the internal stiffener 314 approximately crescent shaped in this example. Preferably, the width Z is substantially greater than the thickness R so that the internal stiffener 314 and the flexible dissecting blade 302 will preferentially bend around the central axis, but will resist bending about an axis perpendicular to the central axis, enhancing the differential stiffness of the flexible dissecting blade 302. Preferably, the internal stiffener 314 and the flexible dissecting blade 302 are made with an initial curvature, as seen in the distal end view of FIG 13. Typically, the internal stiffener 314 will be made of a resilient, elastic material, however in some cases it may be desirable to make the internal stiffener 314 of a malleable material so that the flexible dissecting blade 302 can be bent to a desired curve or shape.

FIGS 14, 15, 16 and 17 show another flexible blade dissector 350 illustrating an alternate geometry for the flexible dissecting blade 352. FIG 14 is a front view, FIG 15 is a distal end view, FIG 16 is a side view and FIG 17 is a perspective view of a distal portion of the flexible blade dissector 350 with the flexible dissecting blade 352 mounted on a catheter shaft 354 with a guidewire lumen 360. In this illustrative embodiment, the distal edge 356 of the flexible dissecting blade 352 has a nose 362 that extends distally beyond the lateral wings 364, 366 of the flexible dissecting blade 352. The nose 362 of the flexible dissecting blade 352 is convex or semicircular, as seen from the front view of FIG 14, and serves as an advance dissector to create a path along the separation plane between the plaque and the underlying medial layer for the wider lateral wings 364, 366 to follow. This creates a two- stage dissecting effect, similar to the coaxial system of FIGS 5 and 6, using a single flexible blade dissector 350. Alternatively, this flexible blade dissector 350 can be used very effectively as the second flexible blade dissector 150 in the coaxial system of FIGS 5 and 6. For this purpose, the nose 362 of the flexible dissecting blade 352 may be made with a blunt and rounded distal edge 356. The geometry of the flexible dissecting blade 352 gives it the desired differential stiffness characteristics. The differential stiffness may be further enhanced using any of the constructions described above in connection with FIGS 7-12.

In each of the embodiments described above, the flexible dissecting blade has been made symmetrical. This has the advantage that, in a uniform plaque, a symmetrical dissecting blade will tend to track straight and parallel to the longitudinal axis of the artery. However, in a non-uniform plaque, the resultant forces on a symmetrical dissecting blade may be unbalanced, causing the dissecting blade to veer to the side, taking the path of least resistance. When these conditions can be foreseen, the flexible dissecting blade may be made asymmetrical to compensate to balance the forces so that the dissecting blade will tend to track straight through the non-uniform plaque. However, it is more likely that such conditions will not be foreseen prior to encountering them in a clinical situation. For such situations, it would be beneficial to be able to control the direction of the flexible dissecting blade as it dissects a plaque from the wall of the artery. FIGS 18-42 show various means of steering the flexible dissecting blade 102 to control the direction of the flexible blade dissector 100 as it dissects a plaque from the wall of the artery. Various steering strategies can be used to direct the flexible dissecting blade 102 to the right or to the left within a plane of dissection and/or to direct the flexible dissecting blade 102 outward or inward to change the depth of the plane of dissection within the arterial wall. Three possible steering strategies, characterized as neck-based steering, nose-based steering and wing-based steering, are described below. These three steering strategies can be used separately or in combination with one another. Various steering mechanisms can be incorporated into the flexible blade dissector 100 to implement these steering strategies.

FIGS 18-29 show a flexible blade dissector 100 with neck-based steering. The flexible blade dissector 100 has a bendable neck 130 on the elongated catheter shaft 104 just proximal to the flexible dissecting blade 102. The flexible blade dissector 100 can be steered by bending the catheter shaft 104 at the neck 130 to direct the flexible dissecting blade 102 to the left or right and/or outward or inward with respect to the arterial wall.

FIGS 18-23 show the application of neck-based steering for controlling the radial position of the flexible dissecting blade 102 with respect to the arterial wall. FIGS 18 and 19 show a distal end view and a side view, respectively, of the flexible dissecting blade 102 angulated outward with respect to the arterial wall to direct the plane of separation deeper toward the medial and adventitial layers of the arterial wall. FIGS 20 and 21 show a distal end view and a side view of the flexible dissecting blade 102 steering straight. FIGS 22 and 23 show a distal end view and a side view of the flexible dissecting blade 102 angulated inward with respect to the arterial wall to direct the plane of separation toward the endothelial layer of the arterial wall.

FIGS 24-29 show the application of neck-based steering for controlling the lateral position of the flexible dissecting blade 102 with respect to the arterial wall. FIGS 24 and 25 show a distal end view and a radial inside view of the underside of the flexible blade dissector 100, as if viewing the device from within the arterial lumen, with the flexible dissecting blade 102 steering toward the right from the catheter's frame of reference within the arterial wall. FIGS 26 and 27 show a distal end view and a radial inside view of the flexible dissecting blade 102 steering straight. FIGS 28 and 29 show a distal end view and a radial inside view of the flexible dissecting blade 102 steering toward the left from the catheter's frame of reference within the arterial wall.

Various steering mechanisms can be used to implement the neck-based steering strategy. FIG 30 shows an embodiment of the flexible blade dissector 100 having neck-based steering provided by a rotatable external guide catheter 132 for controlling the direction of the catheter shaft. The external guide catheter 132 may be preformed into a curve or it may be malleable or heat formable at the point of use. Alternatively, the neck-based steering strategy can implemented using an internal steering tube, as described below in connection with FIG 32, or using control wires, as described below in connection with FIGS 33-38. FIG 31 shows the application of nose-based steering for controlling the radial position and lateral position of the flexible dissecting blade 102 with respect to the arterial wall. The flexible blade dissector 100 is made with a movable nose 134 at the distal end of the catheter shaft 104. The movable nose 134 may be integral with the flexible dissecting blade 102 or it may extend distally of the flexible dissecting blade 102, as shown in this exemplary embodiment. The movable nose 134 acts as a blunt dissecting probe for extending the plane of dissection in a desired direction within the arterial wall for the flexible dissecting blade 102 to follow. The movable nose 134 can be flexed up and down to direct the flexible dissecting blade 102 radially outward or inward with respect to the arterial wall. The movable nose 134 can also be flexed to the left and right to direct the flexible dissecting blade 102 left or right within the arterial wall.

FIG 32 shows a cutaway view of an embodiment of the flexible blade dissector 100 having nose-based steering provided by a rotatable internal steering tube 136 within the lumen 110 of the catheter shaft 104. The internal steering tube 136 may be preformed into a curve or bend 138 or it may be malleable or heat formable at the point of use. The internal steering tube 136 may be constructed of metals, such as stainless steel or a superelastic nickel-titanium alloy, polymers or a composite construction, for example a fiber reinforced or wire braided composite or a coil reinforced and/or counterwound torque tube. Preferably, the internal steering tube 136 includes an internal guidewire lumen 140 for passage of a guidewire 124. Alternatively, the internal steering tube 136 maybe replaced with a solid stylet that is precurved and/or malleable so that the user can create the desired curve at the point of use. For nose-based steering, the internal steering tube 136 is inserted into the lumen 110 of the catheter shaft 104 until the bend 138 is positioned within the movable nose 134 of the flexible blade dissector 100. If desired, an internal shoulder 126 may be provided near the distal end of the lumen 110 to prevent the steering tube 136 from being inserted beyond the distal end of the catheter shaft 104. The steering tube 136 is rotated from its proximal end to steer the movable nose 134 of the flexible blade dissector 100 in the desired direction. Neck- based steering and wing-based steering can also be implemented using an internal steering tube 136 by inserting or withdrawing the internal steering tube 136 until the bend 138 is positioned at the bendable neck 130 or the wing region 128 of the catheter shaft 104. Alternatively, the nose-based steering strategy can implemented using control wires, as described below in connection with FIGS 33-38.

FIGS 33-38 show the application of wing-based steering utilizing control wires for controlling the radial position and the lateral position of the flexible dissecting blade 102 with respect to the arterial wall. FIG 33 shows a distal end view of the flexible blade dissector 100. FIGS 34, 35 and 36 are side views of the flexible blade dissector 100 cut away along the section line shown in FIG 33. The flexible blade dissector 100 includes an upper control wire 142 and a lower control wire 144 that extend through the catheter shaft 104 from the proximal end and attach to the wings 114, 116 of the flexible dissecting blade 102 (or to the wing region 128 of the catheter shaft 104 in the vicinity of the flexible dissecting blade 102). The upper control wire 142 is attached near the top of the leading edge 106 of the flexible dissecting blade 102 and the lower control wire 144 is attached near the bottom of the leading edge 106 of the flexible dissecting blade 102. In FIG 34, the upper control wire 142 has been pulled from its proximal end to angle or curve the flexible dissecting blade 102 upward to steer the flexible blade dissector 100 radially outward with respect to the arterial wall. In FIG 35, no steering is applied. In FIG 36, the lower control wire 144 has been pulled from its proximal end to angle or curve the flexible dissecting blade 102 downward to steer the flexible blade dissector 100 radially inward with respect to the arterial wall. If desired, additional control wires may be provided for individually controlling the upward and downward pitch of the wings 114, 116 of the flexible dissecting blade 102.

FIGS 37 and 38 are underside views of the flexible blade dissector 100 showing a left control wire 146 attached to the left wing 114 from the catheter's frame of reference and a right control wire 148 attached to the right wing 116 of the flexible dissecting blade 102. In FIG 37, no steering is applied and the flexible dissecting blade 102 will travel straight along the dissecting plane within the arterial wall. In FIG 38, the left control wire 146 has been pulled from its proximal end to angle or curve the flexible dissecting blade 102 toward the left with respect to the arterial wall. Depending on the relative stiffness of the wings 114, 116 of the flexible dissecting blade 102 and the catheter shaft 104, the flexible blade dissector 100 may also exhibit some degree of neck-based steering when the control wires 146, 148 are pulled.

Alternatively, the control wires 142, 144, 146, 148 may be attached to the catheter shaft 104 or to the nose 134 of the flexible blade dissector 100 to implement neck-based or nose-based steering, as described above.

FIGS 39-42 show an embodiment of the flexible blade dissector 100 having wing- based steering provided by inflatable chambers 170, 172 within the wings 114, 116 of the flexible dissecting blade 102. FIG 42 is an underside view of the flexible blade dissector 100. A left side inflatable chamber 170 located in the left wing 114 is connected to a left inflation fitting 174 by a left inflation lumen 176 that extends through the catheter shaft 104, and a right side inflatable chamber 172 located in the right wing 116 is connected to a right inflation fitting 178 by a right inflation lumen 180. FIG 39 is a lateral cross section of the flexible dissecting blade 102 with the right side inflatable chamber 172 inflated with saline solution or the like. When inflated, the right wing 116 will have greater drag force on it as the device is advanced and the flexible dissecting blade 102 will steer to one side. FIG 41 is a lateral cross section of the flexible dissecting blade 102 with the left side inflatable chamber 174 inflated with saline solution or the like. When inflated, the left wing 114 will have greater drag force on it as the device is advanced and the flexible dissecting blade 102 will steer to the other side. In FIG 40, both of the inflatable chambers 170, 172 are deflated and the flexible dissecting blade 102 will steer straight along the dissecting plane within the arterial wall. Alternatively or in addition, the inflatable chambers 170, 172 may also be used to propagate the dissection of the plaque from the artery wall. The inflatable chambers 170, 172 may be inflated separately or together to create a dilating force to separate the plaque from the artery wall.

FIG 43 shows an endarterectomy catheter 1100 with a bulbous section 1102 distal to a wing-shaped dissector blade 1104 to help create a dissection plane between a plaque and the arterial wall. The wing-shaped dissector blade 1104 is preferably flexible to follow the varying contours and diameters along the length of the artery. Various constructions for flexible wing-shaped dissector blades suitable for this and other embodiments of the present invention are described in commonly owned and copending patent application 09/611,837, filed July 7, 2000, which has been incorporated by reference. The diameter of the bulb 1102 may be approximately 2 to 3 times the diameter of the shaft 1106. FIG 44 shows a similar endarterectomy catheter 1100 with a bulbous section 1102 distal to the dissector blade 1104 and a short length of shaft 1108 separating the bulb 1102 from the wings of the dissector blade 1104 to make it easier for the "nose" (distal portion) of the catheter to flex. The bulb 1102 may be position at the distal end of the catheter shaft 1106, as in FIG 43, or the catheter shaft 1106 may have a short flexible distal tip section 1110 extending beyond the bulb 1102, as in FIG 44. The leading 1112 and/or trailing 1114 edges of the wing-shaped dissector blade 1104 may be made with a convex curvature, as in FIG 43, or with a concave curvature, as in FIG 44. A balloon 1116 may be added onto a dissecting catheter shaft 1106. The balloon 1116 may be inflated to help dissect the tissue plane. The balloon 1116 may be used on the shaft 1106 together with a bulb 1102, as shown in FIGS 46-48, or the balloon 1116 may be used instead of a bulb 1102, as shown in FIG 45. The inflatable and deflatable balloon 1116 may act like a variable size bulb. There are many possible locations for the balloon 1116, including: distal to a bulb 1102 (FIG 46), concentrically over a bulb 1102 (FIG 47), between a bulb 1102 and the wings 1104 (FIG 48).

Alternatively, a braid 1118 may be attached to a catheter shaft or two concentric catheter shafts 1120, 1122 so that one end may be moved axially relative to the other, as shown in FIG 49. The distal end 1126 of the braid 1118 is attached to the inner shaft 1120 and the proximal end 1128 of the braid 1118 is attached to the outer shaft 1122. Compressing the braid 1188 axially by pulling the inner shaft 1120 relative to the outer shaft 1122 causes the braid 1188 to expand sideways and propagate the dissection. The braid 1188 may be covered with a thin membrane 1124. The membrane 1124 may be elastic. In any of the embodiments described herein, part or all of the endarterectomy dissector catheter may have a lubricious surface to reduce friction. The dissector material may be lubricious, or a lubricious coating may be applied to a base material. The coating may be hydrophilic (e.g. hydrogel, PVP polyvinyl pyrollidone, PVA polyvinyl alcohol) or hydrophobic (e.g. silicone, PTFE).

The catheter may have a lumen for infusing lubricious fluid. The fluid may be injected at the proximal end of the catheter, and exit at a port or multiple small pores or micropores in the catheter surface. The material may exit the tip of the catheter, or through the wall of a porous balloon, or through pores in the dissector blade wings or catheter shaft. Example fluids include synovial fluid type material with hyaluronic acid, a mucus type material, a protein based lubricous material, a fish slime type material, and silicone. The pores may be similar to that used on drug infusion balloons (e.g. Localmed). Pores may be formed by any of several means, including piercing the catheter with a cutter (e.g. a sharp wire), or by cutting or drilling (either mechanically or with a laser), or insert molding over wires and then removing the wires.

An endarterectomy device 1130 may be made with a flexible ring stripper 1132 to better follow the contours of the artery. The ring 1132 may be split into an overlapping C shape, like a "dial" ring or key ring, as shown in FIG 50. Alternatively, the ring 1132 may be made in sections that telescope to allow for variable circumference, as shown in FIG 51. The endarterectomy device 1130 may have one, two or more support rods 1134 connected to the flexible ring stripper 1132.

An endarterectomy device 1136 may be made with a wire loop 1138 supported by a tube 1140 and a support rod 1142 with an eye 1144, as shown in FIG 52. Suitable materials for the wire loop 1138 include, but are not limited to, stainless steel, NITINOL and monofilament polymer fibers, such as polyester or nylon. The proximal ends 1146 of the wire loop 1138 may be pulled to tighten the loop 1138 and cut across the diameter of the plaque. Referring now to FIGS 53a-53b, an endarterectomy device 1150 may include a first catheter 1152 that carries a wire 1154 in a lumen 1156. The lumen 1156 for the wire 1154 may pass through the dissecting wing 1158 or elsewhere in the first catheter 1152. The proximal ends 1160 of the wire 1154 maybe wrapped around the circumference of the plaque at the proximal surgical site in the patient (e.g. arteriotomy). Then, the proximal ends 1160 of the wire 1154 may be inserted into the distal end 1164 of a second catheter 1162 and threaded out the proximal end 1166 of the second catheter 1162. The first catheter 1152, the wire loop 1154, and the second catheter 1162 may be advanced distally to dissect the plaque away from the vessel. The proximal ends 1160 of the wire loop 1154 may be pulled to tighten the loop 1154 and cut the plaque. The plaque may be cut by a "pinching" action, with the loop 1154 squeezing the plaque until it breaks or cuts. Alternatively, the plaque may be cut by a "slicing" action, with the loop of wire 1154 cutting across the diameter of the plaque. The distal tip 1164 of the second catheter 1162 may be reinforced with a band 1168 (e.g. metal ring) or other means to resist tearing of the second catheter tip 1164 when the wire loop 1154 is pulled tight. The band 1168 may also provide a bearing surface for the wire so that it slides easily. In another embodiment, the wire loop 1154 may be held in a lumen in the first catheter 1152. The wall of the first catheter 1152 may be designed to allow the wire loop 1154 to cut or tear through the wall of the first catheter 1152 when the loop 1154 is pulled tight, and so allow the loop 1154 easier passage across the diameter of the plaque. Alternatively, the first catheter 1152 may carry the wire 1154 in a groove 1170, as shown in FIG 54. The opening 1172 of the groove 1170 may be narrow to help retain the wire 1154 in the groove 1170. When the wire 1154 is pulled tight, the wire 1154 may exit the first catheter 1152 through the opening 1172 of the groove 1170 and then pass across the diameter of the plaque.

A ring stripper 1174 may be continuous, or may be segmented, as shown in FIG 55. Short segments 1176 may be connected by elastic or wire 1178 to form a radially expandable stripper 1132.

A balloon may be inflated in the lumen of the artery and used to guide a ring stripper or dissecting catheter. Inflate the balloon, then push or pull a radially expandable ring stripper or a dissecting catheter along the dissection plane between plaque and vessel wall or within vessel wall (e.g. media). The balloon may help keep the stripper in place or help stabilize the position of the artery.

The balloon may be moldable to the shape of the artery. First inflate the balloon to a high pressure to plastically deform the balloon to the shape of the vessel wall. Then reduce pressure, but still keep the balloon inflated. One suitable balloon for this purpose is a moldable balloon for making a three dimensional image of an artery lumen that is described in U.S. patent 5,316,016 to Adams et al.

An endarterectomy device 1182 may be made with curved loops 1182 of monofilament (e.g.: nylon, polyester, stainless steel wire, NITINOL wire) that extend from the distal end of a tubular shaft 1184, as shown in FIGS 56 and 57. The loop filaments 1182 may extend through lumens 1190 in the wall of the tubular shaft 1184 so that they can be pushed or pulled from the proximal end of tubular shaft 1184 to increase or decrease the size of the loops 1182. The loops 1182 may overlap and/or may be intertwined with one another. The loops 1182 flex to follow the natural plane of dissection between the plaque and the arterial wall. The loops 1182 may be biased radially outward towards the adventitia to reduce the chance of them accidentally breaking through the plaque into the lumen of the artery. The plaque is directed into the central lumen 1188 of the tubular shaft 1184. The tubular shaft 1184 of the device maybe slit lengthwise to allow it to change diameter. The loops 1182 may be individually or collectively covered with a thin membrane 1186 (e.g. polyurethane, silicone, PTFE), as shown in FIGS 58 and 59a-59b, respectively. The membrane 1186 may be inflatable to further propagate the dissection.

The endarterectomy device 1182 shown in FIGS 58 and 59a-59b can also be made from braided filaments. The distal ends of the filaments may be looped as described above. The ends of the wire braid may be looped. When the user pushes the proximal end of the tool, the distal end separates the tissue planes. The forces also put the braid into longitudinal compression, causing the braid to attempt to expand radially. When the user pulls the proximal end of the tool, the drag of the braid against the plaque and vessel wall put the braid into longitudinal tension, causing the braid to attempt to contract radially. This helps hold onto the plaque for easier removal.

It may be advantageous to cut the plaque before removing it. For example, the plaque may be cut circumferentially at one end of the endarterectomy or cut longitudinally one or more times along the length of the endarterectomy section. A sharp edge may be used in combination with a shield. The sharp edge cuts, and the shield keeps the edge from cutting in some directions. An endarterectomy tool may have a sharp blade to cut the plaque. The tool may have a curved shield that matches the concave inner surface of the vessel. The shield may be flexible to allow it to change shape and follow changes in the vessel shape. Part of the endarterectomy tool may reside inside the arterial lumen, and part of it inside the dissection plane. For example, a guide wire, catheter shaft, and balloon may all be used in the lumen. One or more blades may make longitudinal cuts in the plaque as the tool is advanced. These blades may be used to connect the luminal and dissecting plane portions of the tool to each other.

FIG 60 shows an endarterectomy device 1200 having a catheter shaft 1204 with a coaxial guidewire 1206 that resides within the arterial lumen and a dissector shield 1202 attached to the catheter shaft 1204 by a support strut 1208. The distal edge of the support strut 1208 has a sharp cutting edge 1210 that cuts the plaque longitudinally as the dissector shield 1202 dissects the plaque away from the arterial wall.

FIG 61 shows an endarterectomy device 1212 having a catheter shaft 1214 with a coaxial guidewire 1216 that resides within the arterial lumen and a pair of articulating dissector shields 1218, 1220 with cutting blades 1222, 1224 that are pivotally attached to the catheter shaft 1214. Alternatively, the cutting blades 1222, 1224 may be in the form of thin wires capable of cutting through the plaque. The dissector shields 1218, 1220 pivot or flex outward from the catheter shaft 1214 to follow the contours of the arterial walls to dissect away the plaque while the cutting blades 1222, 1224 cut the plaque longitudinally.

A magnet or magnetic material (e.g. steel) may be advanced in the lumen, pulling a magnetically attractable material or magnetic ring stripper along the dissection plane.

Straight guide wires and J tipped guide wires are known in the art. As shown in FIG 62, a U shaped guide wire 1226 may be used instead of a regular straight or J tipped guide wire. A catheter 1100 may be put on one or both legs 1228, 1230 of the U to support the wire 1226 as it is advanced. Alternatively, a first catheter 1100 may be put on one leg 1228 of the U and a second catheter 1100' may be put on the second leg 1230 of the U to support the wire 1226 as it is advanced. As the catheters 1100, 1100' are advanced towards the bend 1232 in the guide wire 1226, the bend 1232 helps create and maintain a separation between the catheters 1100, 1100'. When used for endarterectomy, these devices and methods help increase the size of the dissected region. The catheters maybe regular catheters, or endarterectomy catheters with dissector blade wings, or other catheters.

Straight and J tipped guide wires generally have flexible tips. A U shaped wire 1226 may use stiffness tapers that differ from that used by straight or J tip wires. For example, the entire wire 1226 may be relatively stiff. (When used in endarterectomy, this operates similarly to the Scanlan surgical instrument, but the U shaped guide wire 1226 has the added capability to guide catheters along its length.) Alternatively, the middle 1232 of the wire may be more flexible to help form a U or to be less traumatic, and both ends of the wire (the "legs" of the U) 1228, 1230 may be stiffer. As another alternative, the bend 1232 may be relatively stiff (e.g. to maintain separation between the legs), then the portion of the legs 1228, 1230 next to the bend 1232 may be more flexible (e.g. to reduce potential for trauma), then the remainder of the legs 1228, 1230 may be stiffer.

One or the other leg 1228, 1230 of the U shaped wire 1226 may be advanced or retracted with respect to the other to create an asymmetrically stiff configuration. As the wire is advanced in the dissection plane, it will encounter resistance forces. Because the stiffness of the wire is asymmetrical, the deflections of the wire will be asymmetrical. This asymmetrical deflection may be used to steer the wire as it is advanced. It may also be used to provide a biasing force and keep the wire going straight even if nonuniformity in the tissue or anatomy tries to deflect it to a side.

Alternatively, each leg 1228, 1230 of the U shaped wire 1226 may have a moveable stiffening member. The moveable stiffening member may be in the form of a tube slidable over the exterior of the legs 1228, 1230 or a tube or rod slidable in the interior of the legs 1228, 1230. The stiffening member may be advanced or retracted on one leg of the guide wire 1226 and not the other, to create an asymmetrically stiff wire.

The bend 1232 in the U wire 1226 may lie in a plane, so the wire 1232 appears straight in an end view, as shown in FIG 63a. Alternatively, the bend 1232 in the U wire 1226 may be curved in more than one direction. For example, the wire 1226 may have a second curvature to help match the diameter of the dissection plane. This wire 1226 would appear curved in an end view, as shown in FIGS 64a and 64b.

The bend 1232 may be elastically formed in the wire 1226 or plastically formed in the wire or shape memory formed in the wire.

Multiple U shaped wires 1226, 1226' maybe used. A catheter 1234 may have multiple guide wires 1226, 1226' in a single lumen 1236 if the lumen diameter is selected large enough to accommodate them, as shown in FIG 65b. Alternatively, the catheter 1234 may have multiple lumens to put one guide wire 1226 in one lumen and a second guide wire 1226' in a second lumen. Both legs of one U shaped guide wire may be in the same catheter. This catheter could be retracted with the wire in place, and then two separate catheters could be placed with one on each leg of the U wire. Multiple catheters may be "daisy chained" onto multiple U shaped guide wires. For example, two U shaped wires 1226, 1226' with one to three catheters 1234, 1236, 1238 may form a double U (i.e. "w"), as shown in FIGS 65a, 67 and 68. FIG 65a shows two U shaped wires 1226, 1226' used with three catheters 1234, 1236, 1238. Using a third U shaped guide wire 1226", the daisy chain may be closed to form a complete perimeter around the dissection plane, as shown in FIG 66.

Alternatively, one or more U wires may be used to pull a thin flexible element from one catheter to another and form a loop that encircles the plaque. Pulling the proximal ends of the thin flexible element tightens the loop and cuts the plaque by pinching or by slicing. In one embodiment, each catheter has a lumen that contains the leg of two different U wires. The flexible element is attached to one end of a first U wire proximal to a first catheter. The other end of the U wire is pulled proximally to pull the U wire and the end of the attached flexible element from the first and then from the second catheter. After the end of the flexible element exits the second catheter, the flexible element is attached to a second U wire in the same lumen of the second catheter. The other leg of the second U wire is then pulled to pull the second U wire and attached flexible element further around the circumference of the plaque. Endarterectomy catheters 1240, 1242 may be linked using an alignment element 1244 attached to one catheter 1240, as shown in FIGS 69a and 69b. A first endarterectomy catheter 1240 has an alignment element 1244 (e.g. a thin flexible stainless steel guide wire) attached to a wingtip of the dissector blade 1246. The first catheter 1240 is advanced over a guide wire 1248.

A second endarterectomy catheter 1242 has a hole or lumen 1250 through the opposite wingtip of its dissector blade 1252 (i.e. if the first catheter 1240 has the wire 1244 on the left wingtip, the second catheter 1242 has a hole 1250 on the right wingtip). The proximal end of the alignment element 1244 attached to the first catheter 1240 through the hole 1250 in the wingtip 1252 of the second catheter 1242. The second catheter 1242 is advanced over alignment element 1244. As the dissector blade 1252 on the second catheter 1242 approaches the dissector blade 1246 on the first catheter 1240, the alignment element 1244 will cause the second catheter 1242 to move to the side of the first catheter 1240, widening the endarterectomy in the circumferential direction. The catheters 1240, 1242 may be retracted together to further widen the endarterectomy. FIGS 70a and 70b show a first catheter 1254 with two guide wires or alignment elements 1258, 1260 attached to the catheter wingtips, and a second catheter 1256 with two guide wire lumens 1262, 1264 in the second catheter wingtips. The guide wires 1258, 1260 of the first catheter 1254 are guiding the second catheter 1256. In a preferred embodiment, the first catheter 1254 and the second catheter 1256 are curved oppositely to encircle the perimeter of the artery, as shown in FIG 70b.

FIGS 71-72 show an endarterectomy device 1270 using multiple dissectors 1272, 1274, 1276 linked together. Each dissector 1272, 1274, 1276 has a shaft 1278, 1280, 1282 on one side of the blade 1284, 1286, 1288 and a fixed wire 1290, 1292, 1294 attached to the other side of the blade and extending proximally towards the operator. The lumen 1296 of a first dissector 1272 may be inserted over a guide wire 1268. The lumen 1298 of a second dissector 1274 may then be threaded onto the guide wire 1290 of the first dissector 1272. Multiple dissectors 1272, 1274, 1276 maybe daisy chained together in this way. The daisy chain may form a complete perimeter around the inner artery and plaque being dissected, as shown in FIG 72. The dissector blades 1284, 1286, 1288 may be shaped so they nest together and/or snap/lock together. The blades 1284, 1286, 1288 may be shaped so that later blades can advance as far axially as earlier blades.

An endarterectomy catheter may be linked to the shaft of another catheter. A second catheter 1300 shaft may ride coaxially over the shaft 1304 of a first catheter 1302, as shown in FIGS 73a and 73b. The first catheter 1302 may have a small dissecting blade 1308 and the second catheter 1300 may have a larger dissecting blade 1306. Alternatively, the dissecting blade 1308 of the first catheter 1302 and the dissecting blade 1306 of the second catheter 1300 may extend circumferentially in different directions, as shown in FIGS 74a and 74b. As shown in FIG 75 , a wingtip 1318 of a second catheter 1312 may have a lumen

1322 that slides over the shaft 1316 of a first catheter 1310. More than two catheters may be daisy chained together in this way. Alternatively or in addition, a catheter 1314 may have a small winglet 1320, separate from the dissecting blade wing 1328, with a lumen 1324 that slides over the shaft 1326 of a preceding catheter 1312. The wings of the catheters 1310, 1312, 1314 may be configured to nest together. This embodiment does not require a guiding element trailing from the wingtip of the first catheter.

Alternatively, a second catheter 132 may have a "T" 1336 on a wingtip 1338 that rides captive in a groove 1334 in the shaft 1340 of a first catheter 1330, as shown in FIGS 76a-76b.

FIGS 77a-77d, 78a-78d, 79, 80 and 81 show endarterectomy catheters with a flexible ring stripper. A traditional rigid circular ring stripper has a shaft with a ring that is fixed shape and fixed diameter. The traditional ring stripper does not accommodate to variations in artery size, shape, or angulation. A flexible ring follows the varying contours and diameters along the length of the artery better than a rigid ring. A flexible ring also accommodates variations between different arteries. The flexible ring stripper may be attached to a shaft. The user may hold the proximal end of the shaft outside the patient and move the ring at the distal end of the shaft which is inside the patient. Moving the dissector along the artery dissects the plaque away from the outer artery wall. The shaft may be flexible to follow variations in artery angulation and reduce risk of trauma. The flexible shaft may be made of polymers commonly used in catheter shafts (e.g. PEBAX). The shaft may have a guide wire lumen so the device may be advanced over a guide wire to reduce the risk of perforation or undesired trauma.

For example, FIGS 77a-77d show an endarterectomy catheter 1350 with a flexible ring stripper 1352 on a shaft 1354. The ring 1352 can flex and rotate relative to the shaft 1354 in order to accommodate variations in artery size, shape, or angulation. In use, the ring and shaft are positioned inside the outer artery wall, and the ring surrounds the plaque. The artery and plaque are not shown in FIGS 77a-77d.

As another example, FIGS 78a-78d, 79, 80 and 81 show an endarterectomy catheter

1360 with a shaft 1356 and with a flexible ring 1358 with a wavy or undulating (e.g. sinuous, zigzag) shape. As the artery diameter decreases, the wall of the artery pushes radially inward on the ring 1358. The forces exerted by the artery bend the struts and curves in the ring 1358 and the ring 1358 diameter decreases.

In the preferred embodiment the flexible ring 1358 is elastic, such that when it is radially compressed it pushes radially outward (i.e. attempts to self-expand) towards the artery wall. This bias helps maximize the new lumen diameter rather than cutting through the middle of the plaque. The flexible ring 1358 maybe made of an elastic polymer (e.g. molded

PEBAX, polyethylene, nylon) or metal (e.g. stainless steel, superelastic NITINOL). The ring

1358 may be formed from a wire, for example 0.010 to 0.020 inch diameter stainless steel or

NITINOL. Alternatively, the ring 1358 may be cut from a metal (e.g. NITINOL) tube. Portions of the ring 1358 may be thin or narrow for more flexibility.

As the ring 1358 is pushed by the shaft 1356, it may tend to tilt or cant to the side. The ring 1358 may be shaped to reduce the chance of the ring 1358 digging into the artery wall.

For example, the edges of the ring 1358 may have a smooth radius instead of a sharp edge.

Either end of the ring 1358 maybe bent or curved slightly. FIG 80 shows a wire ring 1358 with a radially inward bend at the leading edge of the ring.

FIGS 82a-82c show a catheter 1362 with dissector blade wings 1364 connected by a flexible segment 1366 to form a variable diameter ring.

Another embodiment of the present invention uses a flexible adjustable loop to make a dissecting tool. Fixed wire loop dissectors with no size adjustability or limited size adjustability are known in the prior art (e.g. Scanlan Endarsector US Design Patent D307323).

The present invention uses loops that may be adjusted from the proximal (handle) end of the device.

FIGS 83a-83c show and endarterectomy device 1370 a filament 1372 (e.g.: nylon monofilament, polyester, stainless steel wire, NITINOL wire approximately 0.007 inch to 0.020 inch diameter) extending from the distal tip of a catheter shaft 1374 to form a curved loop 1376 (approximately 3 mm to 30 mm long). The loop 1376 flexes to follow the natural plane of dissection. The loop 1376 may be preformed (e.g. by shape memory of shape memory alloy such as NITINOL, by plastic deformation of a metal filament, by heat setting of a plastic filament) to follow the circumferential curvature of the artery wall. The loop 1376 may be biased radially outward towards the adventitia to reduce the chance of it accidentally breaking through the plaque into the lumen. The middle of the loop 1376 may be supported by the catheter shaft 1374, for example by routing the loop 1376 through holes 1378 in the shaft or bonding the middle of the loop to the shaft 1374. The two ends 1380 of the filament 1372 extend through a lumen 1382 within the catheter shaft 1374 and exit the proximal end of the shaft 1374.

When using a dissecting catheter 1370 with a flexible loop 1376, the loop needs to be stiff enough to propagate the dissection plane as the catheter is advanced or retracted, but flexible enough to avoid unwanted trauma to the vessel wall (e.g. perforation, tearing completely through the thickness of the wall).

The shaft 1374 may be flexible enough to follow the artery but stiff enough to transmit enough force to dissect the tissue. The shaft 1374 may be a tube (e.g. a polymer such as PEBAX or nylon, shore hardness approximately 50 Shore D to 90 Shore D, more preferably approximately 72D durometer, or an elastic metal such as stainless steel or superelastic

NITINOL). The shaft 1374 dimensions maybe approximately 0.5 to 1.5 mm inside diameter, approximately 1 mm to 3 mm outside diameter, approximately 75 to 300 mm long. The device may be advanced with the loops 1376 retracted, to reduce the amount of force required to advance the device and reduce compression buckling of the catheter shaft 1374. Then the loops 1376 may be extended and the device 1370 retracted to dissect the tissue. Pulling retrograde on the shaft 1374 puts it in tension, so the shaft 1374 does not tend to buckle.

The shaft 1374 may have a lumen 1382 large enough to contain the ends 1380 of the wire loop 1372 and a moveable guide wire. In one preferred embodiment, the shaft 1374 may contain a separate lumen for a guide wire (e.g. steel or NITINOL core guide wire, 0.010 - 0.050 inch diameter, Terumo Glide wire 0.035 inch diameter.)

In one embodiment, the device 1370 may multiple loops 1376 as shown in FIGS 84a, 84e and 84f. Each loop may be extendable and retractable independently from the other. One loop may be more flexible than the other loop, so that either the more flexible loop or the stiffer loop may be used to dissect the tissue. Both loops may be used together. The loop 1376 may be covered with a thin membrane 1384 (e.g. polyurethane, silicone, PTFE, latex rubber, polyester) as shown in FIGS 85a-8b. The membrane 1384 may be inflatable via an inflation lumen in the catheter shaft in order to further propagate the dissection. The membrane 1384 may be elastic so that it expands and contracts to follow the loop 1376 as the loop is extended and retracted. The membrane 1384 provides a smooth surface to reduce the risk of perforation and to reduce the risk of multiple dissections by keeping the leading and trailing edges of the loop 1376 in the same dissection plane. A handle 1386 with a thumb operated ratcheting slider 1388 is provided to adjust loop 1376 length.

FIG 86 shows a partial cross section of a dissecting catheter 1370 with a slider 1388 in the handle 1386 to adjust loop 1376 length. FIG 87 shows a partially disassembled view of the dissecting catheter 1370 with a slider 1388 and handle 1386 to adjust loop 1376 length. FIGS 88a-88c and 89 show operational views of the dissecting catheter 1370 with adjustable loops 1376 made of 0.010 inch diameter straight annealed superelastic NITINOL wire.

Advancing and retracting the slider 1388 axially causes the wire loops to expand and contract sideways to the shaft. The proximal ends 1380 of the wire 1372 maybe supported against buckling in compression by enclosing them in an anti-buckling tube 1390 that is stiffer than the wires. The anti-buckling tube 1390 may be chosen to slide over the outside of the catheter shaft 1274 as shown in FIG 86. Alternatively, the anti-buckling tube 1390 (e.g. SS hypodermic tube 21 TW, 0.023" i.d. x 0.032" o.d. x approx. 100 mm long) may slide inside the catheter shaft 1374, as shown in FIG 89.

The device 1370 may have an additional lumen for delivering radioactive pellets or fluid for radiation therapy. The distal end of the device may have a balloon or other chamber to contain radioactive material. Metal parts such as the dissecting wires or ring may be made of radioactive material or given a radioactive coating. The plastic may be loaded with radioactive powder. The material may have a short half-life and may not be radioactive during manufacturing. The material may be exposed to x-rays or other high-energy radiation shortly before inserting it into the patient to make it radioactive.

The device may have a lumen for other instruments such as a therapeutic ultrasound emitter or for delivering drug or gene therapy. The lumen may be used to deliver chemicals to help dissolve calcium deposits (e.g. similar to those under development by Corazon, Inc.) This may make it easier to create the desired dissection.

In the preferred embodiment the device 1370 has a lubricious coating to reduce friction (e.g. silicone, hydrophilic gel type coating).

When using a dissecting catheter 1370 with a loop filament 1372 of uniform stiffness, the loop 1376 will become more flexible as it is lengthened. It may be desirable to keep the loop flexibility approximately constant, or even to increase loop stiffness as the loop 1376 is lengthened. For example, consider using the same adjustable loop tool in two vessels, a small diameter vessel (e.g. 4-7 mm) and a larger diameter vessel (e.g. 8-12 mm). In general, vessel wall thickness increases with vessel diameter. In the small vessel, the surgeon may use a smaller loop 1376. It may be desirable for this loop 1376 to be relatively flexible to reduce risk of perforating or tearing through the vessel. In the larger vessel, the surgeon may use a bigger loop 1376. It may be desirable for this loop 1376 to be relatively stiff (able to transmit more force with less deflection) to enable dissecting a larger amount of tissue more effectively and efficiently. Because the large vessel has a thicker wall, more force can be applied to the vessel safely.

To accomplish this, the bending stiffness of the loop filament 1372 may vary along the length of the filament. In an exemplary embodiment, the filament diameter tapers (e.g. from 0.007 inch to 0.020 inch diameter), similar to the core wire of a tapered guide wire, as shown in FIGS 90a-90b. When the loop 1376 is short, only the smaller diameter portion 1392 of the filament 1372 is exposed. When the loop 1376 is lengthened, the larger diameter portion 1394 of the filament 1372 is exposed also. The exposed larger diameter wire 1394 increases loop stiffness compared to a filament of constant small diameter.

Alternatively, the composition of the filament 1372 may vary along the length of the filament. The filament material may contain two components (e.g. two polymers with different elastic moduli). When the loop 1376 is short, only the lower modulus portion 1392 of the filament 1372 is exposed. When the loop 1376 is lengthened, the higher modulus portion 1394 of the filament 1372 is also exposed. This tends to increase loop stiffness. The loop filament 1372 may be precurved so that when extended it has a circumferential curvature in the same direction as the circumferential curvature of the artery wall. As more wire 1372 is exposed, the circumferential curvature may change. The stiffer section of the loop filament 1372 may be used to control the position of the more flexible section of the loop filament 1372.

In another embodiment, a catheter 1400 has one or more flexible elements 1402 for dissecting the artery and plaque. FIG 91 shows a side view of a dissecting catheter 1400 with two flexible elements 1402. FIG 92 shows a distal end view of the dissecting catheter 1400 in an artery with plaque. The proximal end of the flexible element 1402 attaches to a shaft 1404 and the distal end of the flexible element 1402 attaches to the distal tip of a control member 1406 that extends through the shaft 1404. Pulling the control member 1406 puts the flexible element 1402 in axial compression and the flexible element 1402 buckles outward. Pushing the control member 1406 retracts the flexible element 1402. The control member 1406 may be a tube that fits concentrically within the outer shaft 1404 and can slide axially relative to the outer shaft 1404. Alternatively, the control member 1406 may be a flexible cylindrical rod (e.g. a wire), as shown in FIGS 93a-93b. The control member 1406 may primarily operate the flexible element 1402 in one direction (e.g. expansion, sideways outward), and the elasticity of the flexible element 1402 may be used to operate the flexible element in the reverse direction (e.g. retraction, sideways inward). The buckling of the flexible element is visually similar to that of a "mushroom" catheter (e.g. Cook Malecot catheter ASMS-14). However, the function of the two devices are very different. The prior art uses mushroom catheters that are soft and atraumatic for retention in a patient, and mushroom catheters typically expand radially in four or more directions. The current invention uses a flexible element to cause a dissection of the artery wall.

The artery may be pressurized with liquid (e.g. saline solution, lubricious hyaluronic fluid, silicone) or gas (e.g. carbon dioxide, nitrogen) to help separate the plaque from the artery wall and to help remove the dissected plaque from the vessel. For example, saline solution may be flushed between the dissected plaque and the vessel wall to help dilate the vessel wall, lubricate the interface between the plaque and the vessel, and flush the plaque and any loose pieces from the vessel. A balloon catheter may be used to occlude the vessel and help maintain elevated fluid pressure in the desired region of the vessel.

An endarterectomy catheter may contain a dissector blade with one or more wingtips guided by a guidewire. A catheter may push the guide wires apart or pull them together circumferentially with respect to the arterial wall, causing the guide wires to help create the dissection. The endarterectomy catheter wing may also help create the dissection. By guiding the catheter wingtip with a guide wire, the chance of accidental perforation of the artery or other unwanted motion of the wingtip is greatly reduced. As an example method, a guide wire may be advanced to create a dissection plane. The guide wire may be chosen to be of a stiffness sufficient to create a dissection, but flexible enough to follow tortuosity (bends) of the vessel. The dissector blade catheter widens the dissection plane. In order to do this it may be chosen to be stiffer than the guide wire. Without guidance, the stiffness of the catheter would reduce its ability to follow tortuosity of the vessel. Each wingtip may be guided with its own guide wire. In the preferred embodiment, a lumen in the wingtip may slide over the guidewire.

Alternatively, a fixed wire may be attached to a wingtip and extend distally to or proximally to the wingtip. The device may be a "rapid exchange" style, with the guide wires exiting the device distal to the proximal end of the device.

In an exemplary embodiment, shown in FIGS 94-95, three guide wires 1428 are placed in the dissection plane. The endarterectomy catheter 1410 has three guide wire lumens 1412, 1414, 1416, one in the shaft 1412 and one in each wingtip 1420, 1422. The endarterectomy catheter 1410 is advanced or retracted over the three guide wires 1428. The dissector blade wings 1424, 1426 and guide wires 1428 create a dissection of the desired width (i.e. portion of circumference of the vessel), and the guide wires 1428 reduce the risk of unwanted motion of the dissector blade 1430.

In another embodiment, shown in FIGS 96 and 100, two guide wires 1428 are placed in the dissection plane. The endarterectomy catheter 1410 has two guide wire lumens 1414, 1416, one in each wingtip 1420, 1422. The endarterectomy catheter 1410 is advanced or retracted over the two guide wires 1428. The dissector blade wings 1420, 1422 and the guide wires 1428 create a dissection of the desired width (i.e. portion of circumference of the vessel), and the guide wires 1428 reduce the risk of unwanted motion of the dissector blade 1430.

In another embodiment, shown in FIG 97, two guide wires 1428 are placed in the dissection plane. The endarterectomy catheter 1410 has two guide wire lumens 1412, 1414, one in the shaft 1418 and one in a wingtip 1422.

In another embodiment, shown in FIGS 98a-98b and 99, the endarterectomy catheter 1410 has a dissector blade 1430 with two wingtips 1420, 1422 and two shafts 1432, 1434 with lumens 1414, 1416 for guide wires 1428. Optionally, the two shafts 1432, 1434 may be joined together 1436 at a point proximal to the dissector blade 1430. Another method for endarterectomy catheters with guidewire guided wingtips follows.

Advance a guide wire to create a dissection plane. Advance a second and third guide wire in the dissection plane created by the first wire. Advance an endarterectomy catheter 1410 over the three guide wires 1428, as shown in FIG 95. The wings 1420, 1422 of the dissector blade 1430 and the guide wires 1428 create a dissection of the desired width (i.e. portion of circumference of the vessel), and the guide wires 1428 reduce the risk of unwanted motion of the dissector blade 1430.

As another example method, advance a guide wire to create a dissection plane. Insert a first lumen 1442 of a three lumen catheter 1440 over the first guide wire 1428, as shown in FIG 101. Advance a second and third guide wire through the second 1444 and third 1446 lumens of the catheter 1440. The catheter 1440 ensures that the second and third guide wires follow the path created by the first guide wire 1428. Remove the catheter 1440, but keep the three guide wires in place. Advance an endarterectomy catheter 1410 over the three guide wires 1428, as shown in FIG 95. Remove the first endarterectomy catheter 1410 and advance a second wider endarterectomy catheter over the guide wires to spread the guide wires 1428 apart and progressively widen the circumferential dissection. The catheters may be designed to be "rapid exchange" type, with the guide wire lumens running from the catheter tip to an exit slot along the side of the catheter shaft.

In another method, the endarterectomy catheter may be removed and flipped to the opposite portion of the plaque circumference, instead of requiring a second endarterectomy catheter. For example, advance a guide wire 1428 to create a dissection plane, as shown in FIGS 102a-102b. Insert a two lumen catheter 1450 over the first guide wire 1428, as in FIGS 103a-103b. FIG 103a is an end view showing the guide wire 1428, catheter 1450, plaque and artery wall. FIG 103b is a side view. For clarity, the artery wall is not shown in the remainder of the side views. Advance a second guide wire 1428' through the second lumen of the catheter 1450. The catheter 1450 ensures that the second guide wire 1428' follows the path created by the first guide wire 1428. Remove the catheter 1450, but keep the two guide wires 1428, 1428' in place, as in FIGS 105a-105b. Advance an endarterectomy catheter 1410 over the two guide wires 1428, 1428', as in FIGS 106a-106b. The first endarterectomy catheter 1410 may be left in place and a second endarterectomy catheter or a two lumen catheter may be placed on the two guide wires on the opposite side of the plaque to create a complete circumferential dissection of the plaque from the artery wall. This method may also be performed using a U shaped guide wire, as described above.

Alternatively, the first catheter 1410 may be removed from the two guide wires 1428, 1428', rotated 180° ("flipped"), and the guide wires 1428, 1428' exchanged to opposite wing tips as follows. Remove the endarterectomy catheter 1410, but keep the two guide wires 1428, 1428' in place, as in FIGS 107a- 107b. Rotate the endarterectomy catheter 1410 approximately 180° about its longitudinal axis. Place the right wingtip lumen 1414 over the proximal end of the guidewire 1428 that had previously been in the left wingtip lumen 1416. Place the left wingtip lumen 1416 over the proximal end of the guidewire 1428' that had previously been in the right wingtip lumen 1414. Advance the endarterectomy catheter 1410 over the two guide wires 1428, 1428', as in FIGS 108a-108b. The catheter 1410 will dissect the remaining portion of the circumference, creating a complete circumferential dissection of the plaque from the artery wall. In another method, the wing 1430 may be flexed to the opposite circumferential curvature, the endarterectomy catheter 1410 maybe moved to the opposite side of the plaque without exchanging guide wires 1428 to opposite wing tips, as shown in FIGS 109a-109d. The endarterectomy catheter 1410 is advanced over two guide wires 1428, as in FIG 109a, dissecting the plaque away along one side of the artery. The catheter 1410 is retracted proximal to a transverse cut through the plaque, keeping the guide wires 1428 in place, as in FIG 109b. The dissecting blade 1430 of the catheter 1410 is flexed to change curvature to the opposite direction, as in FIG 109c. The endarterectomy catheter 1410 is the advanced again over the two guide wires 1428, as in FIG 109d, dissecting the plaque away along the opposite side of the artery.

The dissecting catheter 1460 may have an adjustable width blade 1462, as shown in FIGS 1 lOa-110b. The blade 1462 may be controlled by a slender actuating element 1464 (e.g. a wire) that extends from the blade 1462 along the shaft 1466 and proximally to the operator. The wire 1464 is pulled to widen the blade 1462, as in FIG 110b, and pushed to narrow the blade 1462, as in FIG 110a. Alternatively or in addition, the blade 1462 may have an elastic memory to return the blade 1462 to a narrower position so that it is not necessary to push the wire 1464 to actively narrow the blade width.

The blade 1462 may dissect the tissue directly, or it may support and spread the guide wires 1428 and cause them to dissect the tissue. The dissecting catheter blade 1462 may be spread, then advanced distally. Alternatively, the dissecting catheter 1460 may be advanced with the blade 1462 in the narrow configuration. The blade 1462 may then be widened, and the catheter 1460 may be retracted to further propagate the dissection around the circumference of the plaque. Pulling the catheter 1460 axially to create the dissection reduces the chance of the catheter shaft 1466 buckling, because the shaft is in tension instead of compression. Also, pulling instead of pushing may also reduce the risk of perforation of the outer artery wall.

It may be beneficial to support the plaque, vessel, or endarterectomy devices during endarterectomy with a support means. For example, without stabilization the plaque or dissected inner artery tissue may tend to slide axially in the direction the endarterectomy catheter is being advanced. Undesired tissue movement might cause tissue to pack and jam tighter into the artery and make it difficult to continue advancing the dissection or increase the risk of the endarterectomy catheter perforating the artery. Undesired tissue movement may make it more difficult to retract and remove the plaque. As another example, suppose the endarterectomy catheter 1410 lies in an endarterectomy plane that includes a bend in the artery and the shaft 1418 lies towards the outer side of the bend, as in FIG 111. As the device 1410 is retracted, the shaft 1418 would have a tendency to move towards the inner side of the bend.

An internal support 1470 may reduce undesired movement of the catheter 1410 and the shaft 1418, as shown in FIG 112. An internal support 1470 may reduce movement of the plaque, and may reduce forces or motions that would tend to tear the plaque. This internal support 1470 may help keep the plaque from breaking up into smaller pieces and make subsequent removal easier. In one embodiment, a balloon catheter may be used as an internal support 1470. The balloon catheter is placed inside the artery lumen and inflated to support the inner artery and plaque. In a second embodiment, an expandable braid may be used as an internal support 1470. The braid is placed inside the lumen and expanded to support the inner artery and plaque. The internal support 1470 is placed in the true artery lumen and expanded. Next, an endarterectomy catheter 1410 is placed in a dissection plane in the artery wall and advanced to propagate the dissection. The internal support 1470 may help keep the endarterectomy catheter 1410 positioned in the endarterectomy plane and reduce the chance of the endarterectomy catheter 1410 accidentally moving radially inward towards the plaque and true lumen or radially outward through the outer wall of the vessel.

An internal support 1470 and/or an endarterectomy catheter 1410 may have engaging means (e.g. hooks, barbs, MEMS bristles, mica flakes) to engage the plaque during closed endarterectomy. FIG 113 shows an internal support 1470, such as an inflatable balloon, with a bristle-like engaging means 1472 on its exterior surface.

FIGS 114, 115, 116a- 116b, 117a- 117b and 118a- 118b show a dissecting catheter 1410 with various engaging means 1472. The engaging means 1472 may be positioned on the radially inner surface of an endarterectomy catheter 1410 (i.e. the surface that faces the arterial lumen and plaque, not the surface that faces the outer artery wall). The engaging means 1472 may be in any of several locations, including on the catheter shaft 1418, on a dissector blade 1430, or on a balloon. The engaging means 1472 may be used to stabilize and support the plaque during dissection. The engaging means 1472 may be used to help pull or push the plaque out of the vessel (e.g. through the arteriotomy) after dissection. The engaging means 1472 may be angled in a retrograde direction to allow the catheter 1410 to slide freely over the plaque when advancing the catheter, as in FIG 114. The engaging means 1472 grips the plaque when retracting the catheter 1410, as in FIG 115.

The engaging means may be retractable or erectile. For example, one or more hooks or bristles 1474 may connect to a control means 1476 (e.g. a wire) that slides inside a lumen 1478 in the catheter shaft 1418, as shown in FIGS 116a- 116b. Pulling the wire 1476 causes the hook or bristles 1474 to protrude from a hole or recess 1480 in the catheter 1410 and engage the plaque.

As another example, the engaging means may be MEMS (micro electro mechanical systems) bristles 1482, as shown in FIGS 117a- 117b. The MEMS bristles 1482 may be actuated by "polymeric muscles", such as sulfonated tri-block polymer, which is activated by application of an electric field. The MEMS bristles 1482 connect to a pair of electrical supply wires 1484, 1486 in the catheter shaft 1418. Applying a voltage to the electrical supply wires 1484, 1486 causes the MEMS bristles to deflect and engage the plaque, as in FIG 117b. The surface 1488 of the catheter may contain one or more recesses or depressions 1490 for the MEMS bristles 1482 to retract into.

As another example, the engaging means 1492 may protrude from a movable surface, such as the outer wall 1498 of an inflatable dissecting blade 1500, as shown in FIGS 118a- 118b. When the dissecting blade 1500 is deflated, the engaging means 1492 reside within dimples 1496 in the outer wall 1498, as in FIG 118a. When the dissecting blade 1500 is inflated, the engaging means 1492 stand out from the outer wall 1498 to grip the plaque, as in FIG 118b.

As another example, the engaging means may protrude from a movable surface, for example the outer wall of a double walled balloon or a biogel. The surface may be moved inwards relative to the engaging means to expose the engaging means and engage the plaque. Applying voltage to a catheter surface of biogel "skin" causes the biogel to contract and expose the whisker-like engaging means. The engaging means may protrude and engage when a lumen or balloon is inflated and retract and disengage when deflated. Alternatively, the engaging means may protrude when a lumen or balloon is depressurized and retract when pressurized.

Adhesive may be used to engage and remove plaque. The adhesive may be applied to the surface of an endarterectomy device, an internal support or an auxiliary catheter. The adhesive may exude from pores in the surface of the device to engage the plaque after it has been dissected from the arterial wall. Potential adhesives for engaging and remove plaque include, but are not limited to, adhesives described in U.S. patent 5,156,606 to Chin for a method and apparatus for removing pre-placed prosthetic joints and preparing for their replacement and in U.S. patent 5,575,815 to Slepian for local polymeric gel therapy; BioGlue, bovine serum albumin and glutaraldehyde delivered through static mixer, manufactured by CryoLife International (www.cryolife.com); lipiodol/NBCA/glacial acetic acid, described by Lieber B et al in "Kinetics of embolization in a chronic model of arteriovenous malformation in the swine" BED- Vol. 42, 1999 Bioengineering Conference ASME 1999 pg 651-652.

For example, make a cutdown at the groin and an arteriotomy at the superficial femoral artery. Put an occlusion means at both ends of the section of vessel to be treated. For example, a balloon catheter may be advanced to the origin of the iliac artery, and a second balloon or an external clamp or may be placed superior to the arteriotomy. Large side branch vessels (e.g. the internal iliac artery) may be temporarily occluded with a balloon or other means to prevent excessive flow of adhesive into the branch.

Put adhesive in the true lumen. For example, a lumen in the balloon catheter may be used to inject adhesive. The adhesive may be viscous or may be thixotropic to limit its flow down side branch vessels. Antegrade flow of adhesive into side branches may be reduced or eliminated by temporarily creating stagnant or retrograde flow of blood, saline, or other non- adhesive fluid in the side branches. For example, this may be done by creating a pressure differential (e.g. by elevating pressure in the side branches or in collateral vessels, or by reducing pressure in the parent vessel).

One or more balloons may be used to reduce the volume of tissue adhesive required to make a bond or reduce the amount of adhesive that flows into and is cured inside branch vessels. For example, a balloon may be inflated inside the lumen, leaving a radial gap between the outer surface of the balloon and the inner wall of the plaque and artery. Tissue adhesive may then be injected into this gap and cured. As another example, the tissue adhesive may be delivered through a porous balloon. A second non-porous balloon may be inflated inside the porous balloon. As another example, an expandable braid may be made of hollow filaments with porous walls or holes in the walls. The braid may be expanded radially until it contacts the plaque, then adhesive may be delivered through the filaments pores to bond the plaque.

The surface of the balloon or of a catheter shaft or of a removal tool maybe designed to bond to the adhesive or mechanically engage the cured adhesive. Examples: the balloon may be covered by a mesh or braid or fabric; the wall of the porous balloon may be mesh or fabric; the catheter shaft may have one or more bumps or a braid or a male screw thread.

The tissue adhesive may be mixed with a catalyst or curing agent prior to injection or after injection, so that it cures inside the patient. The tissue adhesive may cure when it comes in contact with tissue. Light or other energy may be delivered to the adhesive inside the patient to cure the adhesive. The tissue adhesive bonds to the plaque. Tissue adhesive may be introduced into both the parent vessel and the branches, but cured mainly in the parent vessel.

(For example, an intraluminal light source in the parent vessel may initiate cure in the parent vessel but not deep into the side branches). Uncured adhesive may flow and be diluted and absorbed by the body without occluding the vessel. Dissect the plaque and inner artery wall from the outer artery wall. This dissection may optionally be made before placing the tissue adhesive.

Pull on the plaque and tissue adhesive together to remove them from the outer artery wall. The tissue adhesive helps keep the plaque together during removal. If one or more balloons were inflated in the lumen during adhesive delivery, these balloons may be deflated to help allow the dissected material to reduce in outside cross sectional area for easier removal.

A ring 1504 and a balloon 1502 may be used to pinch off or cut plaque, as shown in

FIG 119. As one example method, put a balloon 1502 in the arterial lumen. Advance a ring stripper 1504 around the plaque, until the ring stripper 1504 is at the same longitudinal level as the balloon 1502. Inflate the balloon 1502 inside the plaque. The balloon 1502 will push the plaque radially out against the ring 1504 and cut the plaque.

As another example method, put a balloon 1502 in the arterial lumen. Advance a ring stripper 1504 around the plaque, until the ring stripper 1504 is just proximal to the balloon 1502. Inflate the balloon 1502 inside the plaque. Hold the balloon shaft 1506 stationary, and advance the ring stripper 1504 distally to cut the plaque, as shown in FIG 120.

The balloon wall 1502 may be thick to resist being cut through by the ring 1504. The balloon 1502 may have a cut-resistant outer surface (e.g. rubber or rubbery polymer such as latex or polyurethane). The balloon 1502 may be reinforced to resist being cut by the ring 1504. For example, the balloon 1502 may be covered by an external mesh, or by an external fabric, or the wall of the balloon 1502 may contain filaments that resist cutting.

The balloon 1502 may have cutting blades oriented longitudinally, circumferentially or at a helical angle. Multiple loops 1510 may be placed circumferentially around the plaque and tightened or tilted to grasp the plaque for removal. The loops 1510 may be attached to a single catheter shaft. The loops 1510 may be attached to two catheter shafts 1512, 1514, as shown in FIG 121a. Pulling or pushing one shaft axially relative to the other, as shown in FIG 121b, tilts the loops 1510, causing them to hold the plaque. Both catheter shafts 1512, 1514 may then be moved proximally to retract the plaque.

FIG 123 shows an endarterectomy catheter with variable width loops having guidewire lumens on the loops. FIG 124 shows a capture bag device for collecting the plaque. FIG 125 shows the capture bag device of FIG 124 in use. A plaque removal tool for endarterectomy may be formed by attaching a bag or a tube to a shaft. For example, the tool may resemble a bent "butterfly net" with a shaft forming a handle, a ring stripper forming the support for the mouth of the bag, and a bag to collect the plaque. The bag has an opening to insert the plaque. The mouth of the bag is advanced in the dissection plane between the radially outer surface of the plaque and the inner surface of the wall of the newly formed lumen. The bag may be attached to the trailing edge of a dissection tool (e.g. a ring stripper), or the plaque maybe dissected first and then a collection tool with a bag may be advanced to contain the plaque.

FIG 126 shows a capture bag device with a draw string closure to capture the plaque. A means may be provided to close the open "mouth" of the bag so the collected plaque cannot come out of the bag until the plaque is removed from the patient. This helps keep pieces of the plaque from breaking off during removal from the patient.

FIGS 127a- 127b show a capture bag device with a purse string closure to capture the plaque. For example, a thin flexible element (e.g. suture material, monofilament polymer or metal) may form a loop snare or purse string suture around the mouth of the bag. The proximal ends of the element may be pulled to draw the bag closed.

FIG 128 shows a capture bag device with a twisting closure to capture the plaque. As another example, a means (e.g. a rotatable shaft) may be provided to rotate the end of the bag relative to the main body of the bag, thus twisting the mouth of the bag closed (similar to a bread bag).

FIG 129 shows a capture bag device with accordion folds. A bag may be compressed or collapsed, mounted to a shaft, and advanced through the dissection plane or through a true lumen to the distal end of the plaque. For example, a flexible collection bag or tube may be compressed and packed inside a delivery sheath. The delivery tube may be advanced, and then the sheath may be pulled off to deploy the collection bag or tube. The collection bag or tube may have a self expanding structure (e.g. similar to a zigzag stent, a braid (similar to a wall stent) or a helix or loop of superelastic NITINOL wire) to help hold the bag open. After delivery, the mouth of the bag may be placed around the distal end of the plaque and the mouth pulled proximally in the dissection plane towards the arteriotomy to enclose the plaque.

FIGS 130-131 show a braided capture device for collecting the plaque. The bag may have a braid. The braid may be built into the wall, or the braid may form a separate layer. The braid may be elongated axially to compress the bag and plaque radially (similar to a "Chinese finger trap" puzzle). A tube with a distal and a proximal opening may be used to contain plaque. Each end may have a closure means. If the proximal end is kept outside the patient, the tube may be removed from the patient by pulling the proximal end of the tube. In this case, it is not necessary to be able to close the proximal end of the tube. The bag or tube may have a low friction surface (e.g. PTFE, polyethylene, lubricious coating) for easier insertion and removal.

FIGS 132a- 132b show a plaque removal tool with an elongated wing with engaging means. The elongated wing may resemble a long trough with a U shaped cross section. Engaging means on the surface of the removal tool apply traction to the plaque along the length of the plaque. The wing tips may be guided by guide wires. The distal end of the wing may advance the dissection by spreading the guide wires apart or drawing them together. As an alternative embodiment to one short wing or one long wing, several short or medium length wings may be attached along the length shaft for great flexibility in bending and large, distributed surface area for engaging means traction of plaque. FIGS 133 a- 133b show a plaque collection bag or tube with internal engaging means.

The collection bag or tube may be lined with engaging means on the radially inner surface to engage the plaque. The engaging means may angle rearwards (similar to shark's teeth) to trap the plaque inside the tube. This would help keep the plaque from coming out when the bag is retracted. It may not be necessary to close the distal end of the bag. The proximal end of the plaque may be held with a small loop snare, a suture, or other means to maintain position of the plaque as the collection bag or tube is advanced. The plaque holding means may exit a catheter shaft at the proximal end of the collection tube or through a small hole at the proximal end of a collection bag. FIG 134 shows a variable stiffness shaft assembly. A variable stiffness shaft is provided for use in a variety of surgical tools and other applications. The variable stiffness shaft can be used in combination with any of the embodiments of the endarterectomy devices described herein. The variable stiffness shaft has a flexible state in order advance through a tortuous artery or track over a previously positioned guide wire. Then, the shaft can be made into a stiff state to allow better transmission of motion and force from the handle to the distal end. For example, the tool may have a surgical dissector blade at the distal end. With the shaft stiff, the blade may be advanced a short distance. Then, the shaft could be made flexible so the tool would better conform to the natural shape of the patient's anatomy in the region surrounding the tool's new position. Then, the shaft may be made stiff again and the process may be repeated. In one embodiment, the variable stiffness shaft assembly includes a resistance heater and a phase change material that changes stiffness with temperature. In another embodiment, the variable stiffness shaft assembly includes an electrorheological material that changes stiffness when a voltage is applied to it. In another embodiment, the variable stiffness shaft assembly includes a magnetorheological material that changes stiffness when a magnetic field is applied to it.

FIG 134 shows a variable stiffness shaft assembly 900 using reinforcing elements 902, a matrix 904, and a resistance heater 906. The reinforcing elements 902 and/or matrix 904 may be a material that changes phase upon heating or cooling. Preferably the material will have a phase change transition temperature that is slightly above normal body temperature, allowing the variable stiffness shaft assembly 900 to be selectively changed from the flexible state to the rigid state and back the heater. For example, the variable stiffness shaft assembly 900 may be heated above the phase change transition temperature by the resistance heater 906 to melt or soften the reinforcing elements 902 and/or the matrix 904. The variable stiffness shaft assembly 900, while in its flexible state can be introduced along a tortuous path, for example by sliding over a previously placed guide wire. When desire, for example when more force is needed, the variable stiffness shaft assembly 900 is allowed to cool below the phase change transition temperature. The reinforcing elements 902 and/or the matrix 904 harden to convert the variable stiffness shaft assembly 900 into its stiff state. Alternatively, the reinforcing elements 902 and/or the matrix 904 may be made of an electrorheological material. In this case, the heater wires 908 would be replaced by electrode wires configured to apply a voltage across the electrorheological material to change it from a flexible or inviscid state to a stiff or viscous state or vise versa.

Alternatively, the reinforcing elements 902 and/or the matrix 904 may be made of a magnetorheological material. In this case, the heater wires 908 would be replaced by an electromagnetic coil to apply a magnetic field across the magnetorheological material to change it from a flexible or inviscid state to a stiff or viscous state or vise versa. Alternatively, a magnetic field could be applied by an external magnet or electromagnet. The variable stiffness shaft assembly may contain segments connected by a flexible tensile element. When the tensile element is tensioned, the body segments are compressed against each other and the assembly become more rigid. Friction between the components holds them in position. The friction between the elements may be increased by texturing the ends of the segments. For example, the segments may be short tubes and beads strung onto a flexible wire. The bead may have a gritty surface similar to sandpaper. The bead may have a textured pebbly surface like a basketball or football. The bead surface may be soft, so the end of the tube "bites" into the bead when the tensile element is tightened. The beads maybe faceted to provide detented positions. A mechanism may be designed to pull the cable without twisting it (similar to a square bolt mechanism used on a hacksaw frame to tighten the blade.) The bolt can slide axially in the square tube, but it cannot rotate in the tube. The bolt is connected to the flexible tensile cable. Rotating the knob pulls the bolt proximally, putting the cable in tension and the tubes and beads in compression. The jointed shaft maybe enclosed in a flexible plastic tube to make it more atraumatic in the body.

While the present invention has been described herein with respect to the exemplary embodiments and the best mode for practicing the invention, it will be apparent to one of ordinary skill in the art that many modifications, improvements and subcombinations of the various embodiments, adaptations and variations can be made to the invention without departing from the spirit and scope thereof. For example, the elements described in specific embodiments may be combined and permuted to form additional embodiments. References to materials of construction and specific dimensions are also not intended to be limiting in any manner and other materials and dimensions could be substituted and remain within the spirit and scope of the invention.

Claims

What is claimed is:

1. An endarterectomy device, comprising: an elongated shaft having a proximal end and a distal end; and a flexible dissecting blade mounted at said distal end of said elongated shaft, said flexible dissecting blade having a distal edge configured for dissecting a plane of separation between an atherosclerotic plaque and a layer of a vascular wall, said flexible dissecting blade having differential stiffness, wherein said flexible dissecting blade has a greater flexibility about a longitudinal axis parallel to said elongated shaft and greater resistance to bending about a lateral axis perpendicular to said longitudinal axis.

2. The endarterectomy device of claim 1, wherein said flexible dissecting blade has a preset initial curvature, wherein said flexible dissecting blade is curved about an axis parallel to said elongated shaft.

3. The endarterectomy device of claim 1, further comprising an internal lumen extending from said proximal end to said distal end of said elongated shaft.

4. The endarterectomy device of claim 3, further comprising a guidewire sized and configured for passage through said internal lumen of said elongated shaft.

5. The endarterectomy device of claim 1, wherein said flexible dissecting blade has a plurality of longitudinally oriented stiffeners for enhancing the differential stiffness of said flexible dissecting blade.

6. The endarterectomy device of claim 1, wherein said flexible dissecting blade has a plurality of longitudinally oriented grooves for enhancing the differential stiffness of said flexible dissecting blade.

7. The endarterectomy device of claim 1, wherein said flexible dissecting blade has at least one laterally oriented stiffener for enhancing the differential stiffness of said flexible dissecting blade.

8. The endarterectomy device of claim 1, wherein said flexible dissecting blade is approximately diamond shaped with lateral wings extending to the left and right of said elongated shaft.

9. The endarterectomy device of claim 1, further comprising a steering mechanism for directing said endarterectomy device within the vascular wall.

10. The endarterectomy device of claim 9, wherein said steering mechanism comprises a movable nose extending distally from said flexible dissecting blade.

11. The endarterectomy device of claim 9, wherein said steering mechanism comprises a bendable neck on said elongated shaft proximal to said flexible dissecting blade.

12. The endarterectomy device of claim 9, wherein said steering mechanism is configured to change the geometry of said flexible dissecting blade for directing said endarterectomy device within the vascular wall.

13. The endarterectomy device of claim 9, wherein said steering mechanism comprises a first control wire for angulating said flexible dissecting blade in a first direction and a second control wire for angulating said flexible dissecting blade in a second direction.

14. The endarterectomy device of claim 1, wherein said flexible dissecting blade comprises at least one inflatable chamber.

15. The endarterectomy device of claim 1, wherein said flexible dissecting blade comprises lateral wings extending to the left and right of said elongated shaft, a first inflatable chamber within the left lateral wing and a second inflatable chamber within the right lateral wing of said flexible dissecting blade.

16. An endarterectomy device, comprising: a first flexible blade dissector having a first elongated shaft having a proximal end and a distal end, and a first flexible dissecting blade mounted at said distal end of said first elongated shaft, said first flexible dissecting blade having a distal edge configured for dissecting a plane of separation between an atherosclerotic plaque and a vascular wall; and a second flexible blade dissector having a second elongated shaft having a proximal end and a distal end, an internal lumen extending from said proximal end to said distal end of said second elongated shaft, said internal lumen being sized and configured for passage of said first elongated shaft therethrough, and a second flexible dissecting blade mounted at said distal end of said second elongated shaft.

17. The endarterectomy device of claim 16, wherein said second flexible dissecting blade has a width greater than said first flexible dissecting blade.

18. The endarterectomy device of claim 17, wherein said second flexible dissecting blade has a distal edge having a central region and an outer region, wherein at least said outer region of said distal edge is configured for dissecting a plane of separation between the atherosclerotic plaque and the vascular wall.

19. The endarterectomy device of claim 16, wherein said first elongated shaft comprises an internal lumen extending from said proximal end to said distal end of said first elongated shaft.

20. An endarterectomy device, comprising: an elongated shaft having a proximal end and a distal end, and an internal lumen extending through said elongated shaft from said proximal end to said distal end, said internal lumen being sized and configured for passage of a guidewire therethrough; and a flexible dissecting blade mounted at said distal end of said elongated shaft and having lateral wings extending to the left and right of said elongated shaft, said flexible dissecting blade having a distal edge configured for dissecting a plane of separation between an atherosclerotic plaque and a layer of a vascular wall.

21. A method of endarterectomy, comprising: initiating a plane of separation between an atherosclerotic plaque and a layer of a vascular wall; inserting an endarterectomy device having a flexible dissecting blade mounted on an elongated shaft into the plane of separation, the flexible dissecting blade having differential stiffness allowing the flexible dissecting blade to conform to an internal curvature of the vascular wall; and advancing the flexible dissecting blade of the endarterectomy device to longitudinally extend the plane of separation.

22. The method of claim 21, further comprising: inserting a second endarterectomy device having a second flexible dissecting blade mounted on a second elongated shaft into the plane of separation; and advancing the second flexible dissecting blade of the second endarterectomy device to laterally extend the plane of separation.

23. The method of claim 21, further comprising: inserting a second endarterectomy device having a second flexible dissecting blade mounted on a second elongated shaft coaxially over the elongated shaft of the endarterectomy device into the plane of separation; and advancing the second flexible dissecting blade of the second endarterectomy device to laterally extend the plane of separation.

24. The method of claim 21, further comprising: terminating the plane of separation between the atherosclerotic plaque and the layer of the vascular wall; and removing the atherosclerotic plaque.

25. An endarterectomy device, comprising: an elongated shaft having a proximal end and a distal end; a bulbous member mounted proximate said distal end of said elongated shaft; and a flexible dissecting blade mounted on said elongated shaft proximal to said bulbous member.

26. The endarterectomy device of claim 25, wherein said bulbous member has a diameter approximately 2-3 times a diameter of said elongated shaft.

27. The endarterectomy device of claim 25, wherein said bulbous member comprises an inflatable balloon.

28. The endarterectomy device of claim 25, further comprising an inflatable balloon mounted on said elongated shaft at a position offset from said bulbous member.

29. The endarterectomy device of claim 25, further comprising an inflatable balloon mounted on said elongated shaft concentrically over said bulbous member.

30. An endarterectomy device, comprising: an elongated shaft having a proximal end and a distal end; and a dissecting blade mounted on said elongated shaft, said dissecting blade having at least one wing extending laterally from said elongated shaft and having a guide lumen though a portion of said wing.

31. The endarterectomy device of claim 30, wherein said dissecting blade has two wings extending laterally from said elongated shaft, each of said wings having a guide lumen though a portion of the wing.

32. The endarterectomy device of claim 30, further comprising a guide wire lumen extending through said elongated shaft.

33. The endarterectomy device of claim 30, further comprising an elongated guide member attached to said dissecting blade.