WO2016111753A1

WO2016111753A1 - Septotomy catheter for aortic dissection

Info

Publication number: WO2016111753A1
Application number: PCT/US2015/061028
Authority: WO
Inventors: Ramon Berguer; Juan Parodi
Original assignee: Ramon Berguer; Juan Parodi
Priority date: 2015-01-07
Filing date: 2015-11-17
Publication date: 2016-07-14

Abstract

A medical cutting catheter for use, inter alia, in treatment of aortic septal dissections and permits cutting the septum of a dissection- chronic or acute -in a retrograde manner has a base section and a pair of arms. Guide wires extend along or through both arms, and extend or are extendable to a point beyond the ends of the arm. The catheter also contains a harmonic cutting blade which preferably operates by vibration.

Description

SEPTOTOMY CATHETER FOR AORTIC DISSECTION

Field of the Invention:

The present invention relates to a medical catheter that can safely cut through the septum in a retrograde manner in aortic dissections.

Background of the Invention:

Aortic dissection is an uncommon but often lethal condition where the inner layer of the aorta separates from the outer layer creating a double channel. The moving septum thus created disrupts the flow of blood to the legs and viscera. Additionally, the thin wall resulting from the delamination of the aorta often develops into an aneurysm that may eventually rupture.

Generally, a dissection starts by a tear involving the inner layer of the aorta that causes it to separate from the outer layer over part of the circumference of the aorta and a new channel is formed between the separated outer and inner layers of the blood vessel wall of the aorta. This results in the aorta having two channels instead of one. The inner layer of the blood vessel wall that has separated is called the septum (or the flap) and separates the two channels.

One of the two channels formed in a dissection continues to function as a blood vessel, allowing the blood to flow through it. This channel is called the "true lumen." The newly formed second channel through which blood also flows is called the "false lumen." The true and false channel communicate proximally through the proximal tear and distally through one or several distal tears. In some dissecions, there is no distal tear.

A dissection which involves the thoracic aorta is called a "thoracic aortic dissection." There are two types of such dissections. Type A dissections involve a dissection in the ascending aorta, while type B dissections involve any segment of the descending aorta. Type A dissections require immediate surgery. The management of Type B dissection is the subject of controversy. Some doctors advocate temporary medical management, while others advocate immediate stent-grafting. In those cases where the septum is blocking the opening of a major artery supplying the viscera or the leg, urgent surgery may be required and may be limited to a resection of part of the septum (fenestration) providing communication between the true and the false lumen. In a few cases, this needed communication can be achieved by perforating the septum and enlarging the resulting perforation with a balloon (balloon fenestration). A variation of the balloon fenestration which has been attempted involves inserting and advancing two wires through the false and true lumen to a proximal point, and linking the two wires in some fashion to cut the septum with the resulting wire loop. This variation lacks control of the site and of the length of the tearing maneuver. These attempts have been complicated by anecdotal reports of high pressure of the false lumen channel with collapse of the true lumen and by detachment and in folding of the septum obstructing the outflow of the aorta.

One of the wires should be advanced into the true lumen, the other into the false lumen. Entering the false lumen would be easy if both lumena reach down to the femoral artery puncture site. If the false lumen ends proximal to the femoral artery, the former could be engaged by penetrating the orifice of communication between them or by puncturing the septum as distally as possible, inserting a wire in the false lumen and dilating the orifice with a balloon to allow the septotomy cutter to engage the septum at this point. Both wires should come out of the body through the same orifice, either a cut-down in the common femoral artery or a sheath inserted in it.

A catheter which can be used in a retrograde manner is disclosed in US

2011/01 18769. It has a fixed, passive, cutting blade fashioned from a standard surgical small knife which is pushed by an inner tubular component (actuator) against the septum. This passive cutting blade does not permit a controlled septotomy. The actuator acts as a telescopic mechanism by sliding inside the outer tubular component. The coaxial system extending extends throughout the length of the catheter and creates substantial friction that will increase with the any increase in diameter of the two tubular components. A catheter with inner and outer tubular components functioning telescopically does not have the flexibility to navigate the bends of the arterial system and, if some bending has been achieved, then the friction between the two tubular components would increase dramatically. The fixed "Y" assembly in this publication requires a substantially large system for introducing the catheter into the blood vessel because the diverging ends of the two tubular components of the Ύ" that house the blade are attached to the latter with rigid glue.

The catheter of the present invention is somewhat similar in that it is intended to be used in a retrograde manner. It controls the site and length of the septum cut in acute and chronic aortic dissection. In the former, it equalizes the pressure in both lumena, potentially avoiding the development of an aneurysm, as well as correcting malperfusion of the viscera or legs. In chronic dissections, where different viscera may be perfused by either lumen, it converts the double lumen into a single one and thus cutting the fibrous septum of a chronically dissected aorta permits insertion of a branched endograft in a manner similar to that used in thoracoabdominal aneurysms. The present catheter has no mechanical actuator and hence it can be constructed with a small profile. It employs a harmonic knife to cut the septum which works on contact without any need for a mechanical push mechanism. As a result, the catheter can have a small diameter and an increased the flexibility which facilitates its advancement the catheter through a tortuous aorta. The harmonic blade cuts by ultrasound energy and its high frequency vibration is delivered by a minute piezoelectric ceramic which is energized through a thin electrical wire imbedded in the catheter. The cut is precise, occurs irrespective of whether the harmonic blade is submerged in blood, and generates minimal heat.

The instant catheter avoids the need for a mechanical actuator which would need to be operated from the entry point of the catheter to its end, usually about 70-80 cm away, and allows the construction of a cutting catheter with a low profile since it does not need rigid mechanical actuators for the blade. The present catheter has the flexibility needed to accommodate the curves of the aortic and iliac arteries system. The bifid end of the catheter, when introduced, is collapsed and has the same diameter as the rest of the catheter. Its two arm only open when the wires that guide them diverge after encountering the lower end of the septum.

Summary of the Invention:

A medical cutting catheter that can be used to cut the septum of an aortic dissection (septotomy), whether the dissection is acute or chronic, has a base section with a pair of arms extending from an end thereof, through guide wires extend through and beyond the arms to guide the septotomy catheter such that the area defined by the vertex formed by the arms and base region will engage the septum when advanced into the blood vessel. At this vertex where the septum edge is engaged, a harmonic blade cuts the septum as the catheter is advanced using the guide wires as essentially parallel rails.

Brief Description of the Drawings:

Figure 1 is a perspective view of the catheter before insertion into a blood vessel. Figure 2 is a perspective view of the catheter after insertion into a blood vessel as it engages the lower edge of the septum guided by the two guide wires.

Figure 3 is a sectional view of the catheter through the middle of the plane of the blade. Figure 4 is an embodiment of the catheter having wings to better align the catheter with the center axis of the septum.

Description of the Catheter:

The catheter of the present invention is used for cutting a septum in an aortic dissection, whether acute (where the septum is thin and mobile) or chronic (where the septum is thick and immobile). The catheter can, for instance, be inserted into a dissected aorta in the treatment of Type B thoracic aortic dissections. The Figures show the device as described below, and use the same reference numeral for the same element in each drawing.

Figures 1 and 2 show a catheter 1 having a base section 2 from which a pair of arms 3, 4 extend. Figure 1 shows catheter 1 being advanced into a blood vessel whereas Figure 2 shows catheter 1 after insertion and separation of the arms 3, 4 resulting in the distal end of the device assuming a general Y-shape. The arms of the catheter do not diverge into a Y shape until guide wires separate them at the lower edge of the septum. Arms 3, 4 converge at the point they both abut base section 2. Figure 2 illustrates the situation when the first arm 3 of the catheter is disposed in the true lumen 5 while the second arm 4 of the catheter is disposed in the false lumen 6 and a septum 7 is located between the two arms.

A pair of guide wires 8 traverse the base section 2 and arms 3, 4, through a channel system. The guide wires 8 have been inserted into the blood vessel and advanced into the true and false lumens. Thus, both guide wires have entered the femoral artery through the same puncture or through a sheath inserted into the artery. The proximal ends of the guidewires which are outside the body are fed into the channel(s) at the end of the catheter and pushed through the channels until their proximal ends emerge at the end of the catheter. The catheter is then advanced into the artery along these parallel wires until it encounters the lower edge of the septum (see Figure 2). The guide wires 8 are caused to extend beyond the ends of the arms to beyond the point where the cutting of the septum will cease. Since the guide wires 8 are constrained by the blood vessel walls 10, they are roughly parallel to each other and the axis of the blood vessel.

Each of the guide wires 8 extend through a channel 11 which traverses base section 2 of the catheter and the respective arms, although in other less preferred embodiments, the channels can be on a surface of the arms. A single channel may traverse the base section 2 and then separate into different channels in each arm, or a pair of channels for each of the arms may be employed in base section 2. Located at a vertex 12 formed by the end of the base section and the two arms 3, 4, is a cutting assembly. The cutting element may be a harmonic cutting blade 13 connected to an ultrasonic static motor 14. See Figure 3. The ultrasonic motor 14 can take the form of a piezoelectric device (ceramic PTZ disks) connected to blade 13, energized through a thin conductor (wire) imbedded in the catheter that delivers electric current. Motor 14 is preferably housed within base section 2. The ultrasonic static motor transforms electrical voltage into high-frequency (approximately 50,000 Hertz) vibration, and the vibration is transmitted to the cutting blade 12 and causes the blade to cut through the septum on contact. The cutting is carried out with the vessel lumen filled with blood and generates minimum local heat (about 50° F) at 1 mm distance from the blade.

The cutting assembly moves so that it cuts along the length of septum 16 using the guide wires 8 to provide a track for catheter 1 to follow. The guide wires 8 thus lead the arms 3, 4, of catheter 1 into the blood vessel and when the arms diverge into the false and true lumena, 6 and 5, respectively, they receive the distal edge of the septum 7 between them. See Fig. 2.

In an additional embodiment as shown in Figure 4, the distal end of the catheter has a pair of flexible wings 18, preferably small, on the outer aspect of the base section or the split ends to better align the harmonic blade with the center axis of the septum. The wings may have a fixed shape or be collapsible so that they can be carried on or inside the catheter until the bifid expand. The wings 18 shown in the drawings are in the form of a loop made of the same plastic as the catheter . This embodiment can be used when the catheter of the invention is introduced into the blood vessel by insertion into a hollow outer catheter or similar body so that when the inventive catheter protrudes from the introducer element, the wings 18 expand (open), when it is withdrawn back into the introducer the wings fold forward onto the outer walls of the base section or arms.

After the cutting of septum 7 is complete, catheter 1 is withdrawn from the blood vessel.

Various changes and modifications in the above described catheter will be apparent to those of ordinary skill in this art. The embodiments described above were for illustration purposes and were not intended to be limiting.

Claims

What is Claimed is:

1. A catheter, comprising:

a base section having an end from which a pair of arms extend,

a base section channel extending through the base section,

a first channel extending from the base section channel through one of the arms and adapted for passage of a guide wire,

a first guide wire extending through the first channel,

a second channel extending from the base section channel through the other armand adapted for passage of a guide wire,

a second guide wire extending through the second channel, and

a harmonic cutting blade disposed between the arms at about the base section end.

2. The catheter of claim 1, wherein the cutting blade is a vibratory cutting blade.

3. The catheter of claim 2, further comprising an ultrasonic static motor.

4. The catheter of claim 3 in which the motor comprises a piezoelectric element disposed to vibrate the blade at ultrasonic frequency.

5. The catheter of claim 4, wherein the motor is disposed inside the base section channel of the catheter.

6. The catheter of claim 5, further comprising at least one conductor disposed in the base section of the catheter in electrical communication with the motor.

7. The catheter of claim 6, wherein the guide wires extend beyond the arms for a distance of approximately the length of a desired cutting

8. The catheter of claim 7, having a pair of wings laterally extending from the distal end of the catheter.

9. The catheter of claim 1, wherein the cutting blade is a vibratory cutting blade and further comprising a first guide wire extending through the first channel, and a second guide wire extending through the second channel.

10. The catheter of claim 9 in which the motor comprises a piezoelectric element disposed to vibrate the blade at an ultrasonic frequency.

11. The catheter of claim 10, wherein the motor is disposed inside the base section channel of the catheter.

12. The catheter of claim 1 1, further comprising at least one conductor disposed in the base section of the catheter in electrical communication with the motor.

13. The catheter of claim 12, wherein the guide wires extend beyond the arms for a distance of approximately the length of a desired cutting

14. The catheter of claim 12, having a pair of wings laterally extending from the distal end of the catheter.

15. The catheter of claim 1, wherein the guide wires extend beyond the arms for a distance of approximately the length of a desired cutting.

16. A method of eliminating a septum in a blood vessel which comprises inserting the arms of the catheter of claim 9 into the blood vessel such that one arm extends into a true lumen and the other arm extends into a false lumen, and moving the catheter along the guide wires such that the blade cuts the septum.

17. The method of claim 16, wherein the blade is a vibratory cutting blade and is caused to vibrate and move the catheter.