CA2234706A1

CA2234706A1 - Microcatheter

Info

Publication number: CA2234706A1
Application number: CA002234706A
Authority: CA
Inventors: George B. Wallace; Michael L. Jones; Scott Evans
Original assignee: Individual
Current assignee: Micro Therapeutics Inc
Priority date: 1995-11-13
Filing date: 1996-11-13
Publication date: 1997-05-22
Also published as: AU1051897A; EP0861100A1; US6306124B1; EP0861100A4; US6254588B1; WO1997017998A1; US5843050A; JP2000500366A

Abstract

Disclosed is an elongate flexible microcatheter (10) for diagnostic and/or therapeutic applications. The microcatheter is provided with a small outside diameter and high degree of flexibility to facilitate negotiation of small, tortuous vessels such as those encountered in intercranial catheterization.
The catheter is formed from a composite of a series of tubular elements (30), each extending axially for a different distance along the tubular body. A
distal section (32) on one or more of the tubular components is provided with a spiral cut, to modify the flexibility properties of the finished catheter.
The catheter may also be provided with an iflatable balloon (112), and a valve (126) to permit the use of a single lumen (120) for both receiving a guidewire and for conveying inflation media.

Description

W O 97/17998 PCT~US96/18227 MlCRaGATHETER
Ba~k~ ~ ' of the Invention The present inVentiDn relates to catheters for medical ~ or ' _ use. In pal ', the present invention relates to ~ I ~ ' a of the type pal i' ' 1~ adapted for r . ~ i ~ tortuous pal;.. a~ in soft 5 tissues, such as the brain.
A wide variety of catheters have been -' ~,.', I, for, ._: insertion into the vascular system to accomplish any of a number of ~- " : or i' ~b; ~;..,s. For example, a wide variety of balloon dilatation catheters adapted for l I ~ 1~. ' ~ ' coronary angioplasty are known. r~ vascular dilatation catheters, _ O ~ ' ~ catheters, drug delivery catheters and others are well,, 0 : ' in the prior art.
However, due to the relatively large diameter and minimal lu~ i y of the r ~1 ~, d and, to a lesser extent, the coronary 1,_ ' ~, the prior art catheters are typically unsuited for use in the small tortuous vessels, such as those found in the soft tissue of the brain and liver. In addition to size r ~ imposed by such soft tissue ~ s ' ~, catheters suitable for these a,,' i must also exhibit optimal flexibility, while at the same time i " adequate column strength and other desirable, ,, li.,s. In general, the known catheters for 15 one reason or another are unsuited for 1.,. ' r ' i~ai- ~ Such c- ' ~ are useful for a variety of d, - ~ and I~ - ' i ' ~, including drug delivery, imaging, Il. of _ tumors, all~ 'fc . and the like.
For example, in . ~9 0 h~" catheters are designed to deliver a r ' a, , agent to a target site within a blood vessel, to allow ,. ' " _, ' viewing of the vessel and blood flow r,ha~ lio;~ near the release site. For 20 the 1" of localized disease, such as solid tumors, catheters allow a ' , agent to be delivered to the target site at a relatively high L " '- . with minimum overall side effects. Methods for r. ' ~ ~, localized vaso o- ' ~ in target tissue regions, by catheter injection of a vaso-occlusive agent, have also been h Often the target site which one wishes to access by catheter is buried within a soft tissue, such as brain or liver, and is only reached by a tortuous route through vessels or ducts typically having less than about a 3 mm 25 lumen diameter. The difficulty in accessing such regions is that the catheter must be qUitQ flexible, in order to follow the tortuous path into the tissue and, at the same time, stiff enough to allow the distal end of the catheter to be ' lud from an external access site, which may be as much as a meter or more from the target site.
Two general methods for accessing such;: p~-~h regions have been devised. The first method employs a highly flexible catheter having a 'lai ' ', but prc; - od balloon at its distal end. In use, the balloon 30 is partially inflated, and carried by blood flow into the target site. The balloon is 'l~ inflated during ;-' : to replenish fluid leakin~ from the balloon. A major limitation of this method is that the catheter will travel in the path of highest blood flow rate, so many target sites with low blood flow rates cannot be a~
In the second prior art method, a lu", ~ ~ guide wire having a distal bend is guided, by " llali.. 1~
rotating and '~. ~ the wire, to the target site. With the wire in place, the catheter is then advanced along the 35 wire until the distal catheter is then advanced along the wire until the distal catheter end is p- ~i ' at the target site. An pr i ad~ ll, of this method is the ability to control the location of the catheter along a tortuous W O 97/17998 PCT~US96/18227 path. T. I, '' guide wires which csn be guided into delicate, tortuous, and narrow ., ' ~ are available.
However, it is often difficult or pr ' ' to advance a catheter over the wire, especially where the wire extends along a tortuous path of more than about 10 cm. If the catheter is relatively rigid, it cannot track over the final distal portion of the wire in the tortuous path region, because catheter -~ buckles the wire in a narrow 5 turn, or because catheter ~ pulls the wire out of the distal vessels. On the other hand, I.t~Lh~,t~l~, having more flexible shafts, such as those used in balloon f; )~ :' L..t~.d devices, lack the column strength in the catheter's proximal section to be advanced over the guide wire without buckling.
The need in the art for suitably flexible and small diameter medical catheters is exempiified by the s~,~ti~
I ~,. ' re of vascular disorders of the brain a ' with stroke. Stroke is curreotly the third leading cause of 10 death in the United States with an a ' annual cost of $30 billion. In the United States alone, stroke affects in excess of 500,000 A annually, resulting in 150,000 deaths. Current lll options are relatively limited and generally highly invasive.
Thus, there remains a need in the art for the ' .~' r ' of catheters useful in minimally invasive , _1 ' tS to diagnose and treat vascular diseases of the brain, such as those e- ~ ' with stroke, and other~5 diseased sites a c '' through only the small vessels of the L;~l ' ~ y system .
Summarv of the Invention In e~r d :f with one aspect of the present invention, there is provided a ~ .- ': for r v- - '- v small tortuous vessels. The catheter . ivvs an elongate flexible body, having a tubular wall and at least one lumen extending axially i' ~ ' ~ v' A first tubular element is provided in the wall, _ ' ~ from a proximal end 20 of the catheter throuovh the body and l~l v in a first distal zone. A second tubular element is provided in the wall, extending axially from a proximal end of the catheter through the tubular body and terminating in a second distal zone. Each of the first and second tubular elements is provided with a spiral cut in each of the first and second distal zones.
r,t rl, hl~, the first tubular element is disposed coaxially within the second tubuiar element. The second 25 distal zone is ",~1., '' axially displaced from the first distal zone.
In one ' - ' t, the catheter further r . ~ s a spring coaxially disposed within the tubular wall. The spring may be ~fm ~ ' ' on the radially exterior side of the first tubular element and on the radially interior side of the second tubular element.
In - d with another aspect of the present invention, there is provided a method of r 30 a highly flexible small diameter catheter. The method ~ s the steps of providing an elongate tubular element having a distal zone in which the tubular element is provided with a first spiral cut.
A spring coil is pr ' coaxially about the outside of the first tubular element, such that the spring coil extends distally from a proximal end of the catheter to a point which is spaced apart proximaliy from the distal end of the first tubular element.

CA 02234706 l998-04-09 W O 97/17998 PCT~US96/18227 r~efL, ' 1~, a second tubular element is provided having a proximal solid walled zone and a distal spiral cut zone. The second tubular element is F ~ e ~ coaxially about the spring coil, such that the second tubular eiement extends from the proximal end of the catheter to a point which is proximal to the distal end of the spring coil.
P~rL. ' 1~, an outer tubular jacket is pc - ' around the outside of the ~ formed above, and 5 the outer tubular jacket is radially reduced such as by the 3~ of heat to form a highly flexible small diameter catheter.
Further features and . 1~ " will become apparent from the detailed ' ~ ir:- of preferred bc " which follows, when ce ' Ld together with the attached drawings and claims.
Brief De~ of the Drawinns Figure 1 is a side l!k.~al ' view of a , '-: in ~ - d with one aspect of the present i. ' Fipure 2is a cross S~ ii)nal view alony the lines 2-2 of Figure 1.
Figure 3is a r,.~ : y cross-sectional side el~._: ' .., ~ ..~~ of the catheter of Fiyure 1.
Figure 4 is a side el~ -' cross_: ' view of an alternate '-" of a ~ r.~ ' in 9 r r ' with the present invention.
Fi~ure 5is a r. 1~l y, ~ ~;. view of the distal end of a catheter including a valve.
Figure 6 is a side ~I~. ' cross sectional view of a distal end of a catheter including a valve.
Figure 7 is an end el~._- ' view taken along the lines 7-7 in Figure 6.
Figure 8 is a side ~,k,...... ' cross-~ ' view of a distal end of a catheter including an alternate bc ' l of a valve.
Fi~ure 9 is an end: ' . ' view taken alony the lines 9 9 of Figure 8.
Figure 10 is a side IJ~.ai ' cross-s__: ' view of an alternate: b~' : of a valve.
Figure 11 is an end Lk..ai' ' view taken alon~ the lines 1111 in Figure 10.
Figure 12 is a side .,k,..... ' cross 5 ' ' view of an alternate: ' " : of a valve.
Figure 13 is an end .' .~ ' view taken along the lines 13-13 in Figure 12.
Figure 14 is a side ~I~' view of the distal end of a balloon ~ ~ ': in e d -P with the present ..
Figure 15is an end Ll~.. ' ~' view taken along the lines 15-15 in Figure 14.

Detailed D~ ,.i of the Preferred r ~ L
Referrin~ to Figure 1, there is disclosed a .r ': 10 in d e with one aspect of the present invention. '' i' : 10 generally - , i;,es a distal end 12, a proximal end 14, and an elongate flexible tubular body 16 ~ there between.
In an . bc ' : adapted for hll~lLI_ ' ~ I' the catheter body 16 will generally have an outside diameter within the range of from about 0.5 mm to about t.5 mm. The length of the ~ ~ ': 10 will generally be in the range of from about 150 cm to about 175 cm. Qther ;' than those disclosed above W O 97/17998 PCT~US96/18227 and recited cls~ herein can be readily utilized by those of ordinary skill jD the art in view of the herein to suit, ' intended uses of the, .~ ': 10.
The proximal end 14 of r ~ ' - 10 is, t r~ provided with a manifold 18. Manifold 18 i5 provided with at least one access port 20, such as for communicating with distal access port 24 by way of an elongate central lumen 22 (see Figure 3). Central lumen 22 permits the ~c ': 10 to track over a guide wire as is well -' s -d by those of skill in the art. In addition, following, ' of the - ~ r ' 10, as witl be discussed in nreater detail below, the guide wire can be removed and central lumen 22 used to infuse or permit the e ,' ' of other ~- j or ~ ' c~.
In general, the inner diameter of the central lumen 22 is ' ~ - ' with respect to the outside diameter of the ~, ' . ;.~ to provide sufficient wire clearance to allow the catheter to be moved easily over the wire in an axial direction, during catheter ~h at the target site. The 9 ~ ' ~ r ~rL. ~ ~ has a relatively small diameter, to permit its guided .. I along a tortuous path in a target tissue. A preferred g ' ;.~ designed for accessing a taryet along a tortuous path has a diameter within the range of from about .008 inches to about .018 inches.
The guidewire is I Jf~ formed of a material such as stainless steel which is l~.~ -' ' yet flexible in fiber or 15 filament form. Smaller diameter g ~ ' .eS, such as .008 inch wires, are sl.rri..;.,.~tl~ flexible to be .~ d along a tortuous path within a soft tissue. Larger diameter wires, such as .014 and .018 inch wires, may need to be tapered at their distai end regions to .~. along such paths. ~ having a tapered core distal section with a coil wrapping for greater . ~ y in the distal region of the wire are ~ available. The ,, ' . ;.1: has or can be r ~ to have a curved tip, for purposes of guiding the wire along a tortuous vascular 20 path.
The inside diameter of the central lumen 22, pal i- ' l~ in its distal segment, is I l,r~ between about .002 to about .005 inches lar~er than the outside diameter of the guidswire for which ths catheter is designed.
Thus, a catheter designed for use with a .018 inch guidewire has a preferred inside diameter of from about .020 to about .025 inches, and, more r ~f~ , from about .021 to about .022 inches. The preferred .002 to about 25 .005 inch total clearance between the wire and inner wall of the catheter reduces the tendency of the catheter to buckle under - , I ' strain, since the wire provides column support against tubes bending and crimping.
The inside diameter of the central lumen 22 i' ~ v' the proximal portions of the catheter may also be from about .002 to about .005 inches larger in diameter than the outside diameter of the " ' . e, thereby providing column support Ih.. ~' : the catheter. However, a larger diameter for central lumen 22 in the proximal 30 segment would permit greater fluid flow through the catheter, in delivering fluid to the target site. In this em' - ' t, the proximal and distal segments would meet at a step, which would leh,.'l~ be tapered to provide improved fluid flow and g ' . ;.~ slidability.
The ~ I ' 10 can be provided with a single lumen, as illustrated, or with multiple lumen, d, "
upon the diameter - l~ imposed by the intended use and the r 1. of the catheter. If 35 desired, the I . ~ ' can also be r : I d with rapid exchange -, ' ' . such as by providing a guidewire lumen which extends through only a distal section of the ~ ~ ' 10.

CA 02234706 l998-04-09 Referring to Figure 3, there is disclosed a nonscale cross s ~ of a . ~ ' : in dLCu-'- -- with one: ' " l of the present invention. In this: bl " t, the mi.,.~ I' : 10 is provided with an overall length of about 150' ' ~. The elonpate central lumen 22is defined for at least a proximal portion of the !-'I i' ' 10 within a tubular element 30. Tubular element 30 p~ ~r~ a F'~ ; tube, or other material which optimkes the slidability of the . ": 10 over a guide wire (not " t~ atud).
In the i" : dlLd - ' " t, the tubular element 30 extends in a distal direction for at least about 100 c~..li.,.~t~ rG~ at least about 140L ' ~, and, in a particular: bc " t,for about 148 ~.
In an bc " l of the present invention in which the ~ ': 10 has an outside diameter in its proximal section of about .85 mm, the pr1~ r; ~ :b~' tubular liner 30 has a wall thickness of about .002 inches, an inside diameter of about A0 mm, and an outside diameter of about .51 mm.
A distal section 32 of tubular element 30is provided with a spiral cut, to modify the physical, r li~
of the catheter as will be :' i' ' The spiral cut section 32 generally has a length within the range of from about to 15 co"l : ~ r~ within a range of about S, : ~ to about 12 r : ~, and, in 15 a pali ' . ' - " :, extends for a, ~ 10 c~ : ~ in length. The spiral cut generally has a pitch within the range of from about .01 inches to about .125 inches, and in one - h" t, has a 0.06 pitch. In another: bc " t, the distal section 32C ,;,...~. a first spiral cut section having a length of about 5 cm and a pitch of about 0.06, and a second, distal section having a length of about 5cm and a pitch of about .030.
F,~r~ the spiral cut extends . ~ ~ through the wall of the tubular element 30 to produce a helical or coiled ~ ~il The precise pitch of the spiral cut and axial spacing of adjacent windings can be varied widely while still r-- " ' ~ the purposes of the present . i and can be optimi~ed for any particular ..," in view of the 1 ~ ~ herein.
The tubular element 30 in the " t~ d ' " is p~ ' within a coil spring 34. r~rt ~ coil spring 34 extends from the proximal end of the catheter in a distal direction for at least about 100 - ~, although other axial lengths of the coil spring can be readily used ', " " upon the desired flexibility ~,-, lk.~.
of the catheter.
A distal section 36 of the coil spring 34is stretched axially to produce an open wound: ~i~ such that the axial space between adjacent windings of the coil is within the range of from about .07 mm to about 1 mm. The proximal portion of coil spring 34iS generally bottomed out, such that adjacent windings of the coil are in contact with one another. A1~ llali.~, the coil spring can be open wound with .01 mm to 1 mm spacing for the entire length.
A variety of materials can be used to construct the coil spring 34, such as stainless steel, platinum, platinum alloy, nickel, or titanium alloys. Coil spring 34 can be produced from any of a variety of stock forms, such as round cross 5 ' wire, square or other r. ~ ' wire, or polymeric materials as are known in the art.
P~uf~ , coil spring 34is wound from a flat wire made from stainless steel and having cross~
of about 0.002 by about 0.006 inches.

CA 02234706 l998-04-09 WO 97/17998 PCT~US96/18227 -6-The coil sprin~ 34 enhances a variety of desirable, " li~i" such as, ' ' t~ y, and a to kinkinQ or ~ by radially inwardly directed forces. De, " v upon the intended use of the catheter, alternate stiffenin~ ~l.. : t.> can be employed. For example, one or more axially ~ " ~ stiffenin~ wires or rods can be provided between the tubular iiner 30 and the outer tubular jacket 38 as will be ' 5 Qr 1~~ the physical, ~r lk~ of a pal ~iL ' catheter can be readily done by one of ordinary skill in the art in view of the :" ' e herein, for any pal i ' intended use of the catheter.
A proximal section of the .r -' 10 is further provided with a tubular jacket 38 of a relatively stiff material such as r ~ ' Alltllla~ , the jacket 38 may comprise any of a variety of other materials :' . " v upon the desired physical ~ s of the finished .~ ' 10. For example, jacket 38 may be 10 axtruded usin~ polyester or nylon. Alltl~lati..1~, the jacket 38 may be formed from braided materials or braid " Illall~l ' . such as r:l~; . polyester, or nylon.
The jacket 38 extends from the proximal end of the catheter in a distal direction for at least about 50 ~ and ~ , "y within the ran~e of from about gd to about 125 cm. ~f,,..' 'y, the distal end of the jacket 38 if polyimide is used is F- ~ alon~ the catheter body such that it will remain ~ - ' within the 15 ~uidin~ catheter when in use.
A distal section 40 of tubular jacket 38 is provided with a spiral cut, to modify the flexibility r l.
of the r i': 10. r" ~ , at least about the distal most 10 cm of the jacket 38, and, more, ~r~
about the distal most 5 cm of jacket 38 is provided with the spiral cut. As with the spiral cut on tubular element 30, the spiral cut on the jacket 38 may take any of a variety of forms. However, the present inventor has~0 ': . ' that a spiral cut having about a 0.060 pitch spiral is suitable for th e purposes of the present invention.
In the " '~ated e ' -' , the ~,~a~ t.,. 10 is further provided with an outer tubular jacket 42, made from a heat ' i ' '' polyolefin such as r~ h,~ The outer tubular jacket 42, ~r,.~ ~ extends lh.. "' the length of the I ' 10, to provide a smooth exterior surface. The distal end 44 of jacket 42 ,.,~r~ extends beyond the distal end of the pr1~ lel, " G..lh~; liner 30. In the illustrated embodiment, the outer jacket 42 pr~ extends for about 1 L : beyond the distal end of the liner 30.
r~tr~.bl~, the .c -' 10 is further provided with a l_",, marker 26, such as a band of platinum, r ~ old or other material known in the art. The ,_', , marker can be provided in the form of a metal ring, which is, - -' within the outer tubular jacket 42 prior to a heat shrinkin~ step to secure the ,. ', , marker within the outer tubuiar jacket.
Thus, the, .~ ' : of the present invention exhibits a series of zones of relatively i ~ ~ flexibility.
Th~ relative len~ths of each zone can be varied to optimize the desired flexibility profile for pal; ' intended a,," of the catheter.
The first, most proximal zone contains the inner jacket 38. The spiral cut section 40 helps transition the chan~e in flexibility from the first zone to the second zone.

The second zone extends from the distal end of inner jacket 38 to the distal end of sprinOo 34. Distal seOment 36 of sprin~o 34, due to its open wound or "stretched" . ~iv provides a second flexibility transition between the second zone of the third zone.
The third zone extends from the distal end of sprinO 34 to the distal end tube 30. The spiral cut zone 32 5 on thE tube 30 provides a third flexibility transition from the tube 30 to the fourth, most flexible zone.
The fourth zone is 'I~ no more than a floppy tip formed by the extension of outer jacket 42 beyond the distal end of tube 30.
In qeneral, for ;~ aCI ' ,,' ; s the second transition which is spproximately at the distal end of sprin~ 34 will be located at a point within the range of from about 70% to about 95% along the lenpth of the 10 catheter from the proximal end. The r ' - of the third and fourth zones make up the reminder of the catheter lenpth.
The . . :' 10 can be ~; : I,vd in ' e with a variety of I ' ~ . - that will be known to those of skill in the art. Materials utilized in the ~": of uvai' 10 are, ~t~ selected both for their physical I Lr li_v in liqht of the intended end use of the .s :' - 10 as well as for their 15 ' ~ y in the intended use c.. ~ 1. Polymeric materials and metals which are vutt;~ tl~ ' r to be used in ;..I~,.. ' , . - ' ~s are well Lhalavlv.i.~.d in the prior art.
For example, ~ '~lv8lldt .-:h~: tubinq, such as that suitable for tubular element 30, can be '1~ obtained from Zeus, in 0~ v ' uv, South Carolina. The distal section 32 can be provided with a spiral cut, such as by any of a variety of i ' s that can be devised by those of skill in the art. In -- rdv-,.ce with 20 one i ' , . the PTFE or other tubinq is placed onto a mandrel. The mandrel is attached to a machine with a ,~.,. ': ' screw thread. A cuttinq element such âs a razor blade or other sharp ;..vl,. : is placed across the tubinoO and the machine is activated to rotate the mandrel. As rotation of the machine (screw thread) occurs, the mandrel moves axially and r0t 11~ causinOq the tubing to be cut in a spiral manner by the cuttinvo ,' The machine can be set up to cut either a riqht or left hand spiral. The machine can also be set to cut sr or variable pitch spirals, or multizone spiral sections in which each zone has a unique pitch. Spring coil 34 can be wrapped about a suitably sized mandrel as is known in the art, with the distal open wound section 36 formed by oll I v The sprin~o 34 is, d --- ~ -'l~ around the tubular element 30, and thr~ polyimide jacket 38 pr ' ~ about the spring coil 34. Polyimide tubinq suitable for use as the polyimide jackût 38 can be obtained from r ~ Inc., Tampa, Florida and spiral cut such as by the same: ' , " d 1 1. '~.
The ' ' 1~ is then p- ' within an exterior jacket such as a r '~ath,' jacket havinn a " ._.ed wall i' ' of about .004 inches and an outside diameter of about .61 mm. The F- '~atbf; jacket is ' I:atl~:l exposed to a source of heat to shrink the jacket around the b~ to provide a finished catheter body.
In use, a guide wire (not " alvd) is placed within the catheter 10 with its distal tip r"~t " O beyond the distal catheter tip. The ~ ' ' ' vouide wire and catheter are then p_.. - '~ inserted into the patient's v ' - t, and advanced to the p~ u~JHale lllsite. A~, , iall: pr ~ ~ of the I I ' 10 can be c. ' : ' by ~ the ,. ', , marker Z6.
Following proper l ~ ~ of the , ': 10, the ~uide wire is I I ~ 'I~ . ' 'r_ ., from the central lumen 22. ~emoval of the " ' ~ leaves the central lumen 22 avâilâble for . ' .. materials or ~ ~-~ IS are -1~ y to carry out the desired, ,r ' t:. For example, in one a"" of the present ~ . drugs such as :~llL~ may be ~. ' ' through central lumen 22 for delivery at the ll~dt~ ,..l site.
Any of a variety of other " -' or " ~ - tools, or the like may be advânced throuph central lumen 22', ' ~ upon the intended 3~,' ~ of the catheter.
Followin~ l,l 1, the ~ i' : 10 is ".. 11~ . ' ', .. from the patient's ~, '; 1, and the F Lui puncture site is closed and dressed in - ' e with c ._ ' techniques.
Referring to Fi~ure 4, there is disclosed a further ' - ' of the !- I~ ' of the present invention.
The catheter 48 is ~ fil, I,d to provide a c ~ : or er 'l~ - variation in flexibility alon~ its axial length. In this repard, the catheter has a relatively less flexible proximal end, and a highly flexible distal end, with no discrete zones or sudden changes in flexibility in between.
~' ~ ' 48 has a proximal end 50, a distal end 52 and an elon~ate tubular flexible body 54, extendin~
there between. Tubular body 54~ ,i...,S an elongate flexible tubular liner 56 extendin~ from proximal end 50 to a distal terminus 62. The liner 56 in the ' S~ted embodiment has a solid wall from the proximal end 50 up to a l,_ ~ - point 58. In zone 60, which extends between transition point 58 and distal terminus 62, the liner 56 is provided with a spiral cut in - ' with t~ ' , described I ~ herein. ~, ~- v upon the flexibility hal : i;~ desired for a particular catheter, the axial length of the spiral cut zone 60 can be varied from about O ~no spiral cut zone) to about 60 cm. r,l r~ , the length of spiral cut zone 60 will be within the range of from about 2 cm to about 20 cm, and, most, t:le,_"y, the spiral cut zone 60 will be about 10 cm long.
The liner 56 in the i" ~al~.d: '3C' iS provided with a tapered wall i' ~ ' . from a relatively thick wall at the proximal end 50 to a relatively thin wall closer to the distal end 52. Plof~.. "y, the liner 56 has a 25 b~ constant inside diameter ' .~' Iits axial lenpth. In one - b~ ' : of the i.. ~,. . the liner 5B
is provided with a wall thickness of about .Ot2 at proximal end 50, and a wall thickness of about .001 in zone 60.
r,t r~ , the spiral cut zone 60 has an axial lenpth within the ranne of from about 5 cm. to about 10 cm., wlth a variable or constant pitch spiral cut. The terminus 62is,..f~ spaced apart from the distal end 52 of the catheter 48 by about 2 cm.
Liner 56 may be e ~ S,l ' from any of a variety of : ~ Is, dLr " ~ upon the preferred S.
and desired physical, ~, li..~ of the ~ ' : . In the preferred embodiment, the liner 56- ,k..,.
F 1~l~l,ar ~oth,: (PTFE). All~.llati. ~,other ~ Is suchasTFE(softerthanPTFE),otherr; I, 1~
nylon, HDPE, and others that will be known to those of skill in the art can be adapted for use as the liner 56 of the present i .

W O 97117998 PCT~US96/18227 .9.
C~ variable wall thickness tubing, such as that useful for liner 56, can be obtained by v~nt~;h~Ov ~rindinvo of constant wall PTFE tubinnv stock. All~.llali.~!y, liner 56 Gan be provided with a ' i 11~ constant wall thickness i' . ~.' , but with an i ~ ~ v diameter in the proximal direction.
The variable wall thickness tubing can extend for evv~..i 'l~ the entire length of the catheter such as from 5 the proximal end up to the floppy tip. The variable wâll thickness tubing can also be used in only one or more zones of a multi~one catheter. For example, a two zone catheter may comprise a proximal section having a lennvth of from about 50% to about 90% of the overall catheter length. The proximal section may have relatively constant flexibility Ih. _' :, such as the first or second zone in the ' - ' : of Fivgure 3. The distal zone - . ivCO a tapered sevment as described above, ,,.~vf~ with an all_ flexible tip such 8s tip 52.
A coil 64, such as a spring, is disposed coaxially about the liner 56. Spring 64 extends from the proximal end 5D to 3~ the terminus 62. In the illustrated ' ~ ' I, the radius of the spring is provided with a constant taper to ~ Ib, _:Jt to the constant taper on the outside diameter of liner 56. In addition, the sprinnv iS r. vfL. "y provided with a variable pitch such that the catheter 48 exhibits a c ~ chanvne in lateral flexibility from a relatively less flexible chalavl~.ioli~. at its proximal end 50 to a relatively more flexible cl,a.avto.iOlil. at its 15 distal end 52.
Sprinov 64 can be L ~ vd from any of a variety of ; Is. and be provided with any of a variety ~ and other physical ~.hv,avlvlioli-vs as will be a" L.,;atvd by one of skill in the art in view of the d- ' ~ herein. P~vr~ , spring 64 is provided with the physical chàla..l~.ioli..s and r ~,L..,I-,d from the materials identified, v.; '~ herein.
An outer jacket 66 is disposed coaxially about the liner 56 and spring 64, and extends axially 1' ~-v' the lenvoth of the r i' 48 from proximal end 50 to distal end 52. In one ' ' of the i ~. 1, the outer iacket 66 is about 150 cm. in length. A distal section 68 of the outer jacket 66 projects distally beyond the terminus 62. Distal section 68, t:f~ .abl~ has a len~th within the range of from about 1 cm. to about 4 cm., and, more ~vfL~ , is about 2 cm. Distal section 68 may be provided with a ._ ', , marker band (not " ~.~vt~,d) as has been di'-~ d in c : with previous 5~ ~ :
The catheter body 48, vf~ has an overall lennvth of about 150 cm., and d ' radially in outside diameter from proximal end 50 to at least about terminus 62. Generally, the distal sevment 68 will have a - ' : 11y constant diameter i' . ' its axial lenvth. The outside diameter of the catheter 48 at proximal end 50 can be varied widely :', " v upon the intended, ' of the catheter. For cranial , ' s, the outside diameter will generally be less than about .065 inches, and,, ~vfe~ "~, less than about .045 inches. The distal end 52 of the catheter 48 can also be varied in diameter de~endinv upon the intended 1" ' of the catheter 48.
For cranial _., ' . the distal end outside diameter will be less than about .038 inches and, ~ , is about .026 inches or smaller. The overall wall thickness of the catheter 48 can also be varied widely ' . " v upon the desired physical, ~ O of the catheter, and desired ~t i of the central lumen e ~In the i" '~all,d embodiment, as adapted for cranial a, ,' I ~, the wall thickness varies from about .012 inches at proximal end 50 to about .001 inches at distal end 52.

W O 97/17998 PCTrUS96/18227 -1i3-The catheter 48 may ~ be provided with any of a variety of adaptors, s : ~, or manifolds as are well known in the art, and which may be secured to the proximal end 50 in acc~"d with known ~E ' '. - The use of the catheter 48 will be well ' :~d to those of ordinary skill in the art, and, for example, may involve the same ' , disclosed in as '; :f with previous - br " herein. All of the 5 taLII~ , disGlosed herein may be used in asr~, with the 'L ' ', disclosed in U.S. patent no. 4,739,768 to Engelson, the ~ of which is; ~ al~d herein by ,~r, When any of the catheters of the present invention are embodied in the form of an angiographic catheter for " ~ s, certain ~ c, may be desirable as will be apparent to those of ordinary skill in the art. In a d ~ procedure, the primary purpose of these catheters is to allow injection of r " r, contrast 10 material into the '' -' t, to permit imaging of the blood vessel in the form of an c . " .. on X-ray film.
During the process of " ~ - 5 .,' " ~, h~, the contrast medium is usually injected at a rapid rate using a power injector. As a result, the contrast medium is forcefully !" ' ~ ' from the distal end hole of the catheter, creating a jet effect. This may produce an ~ ' ' ' recoil of the catheter, and can also produce a ' " , ~ , ' such as - ' ' injection of the contrast medium, in which the jet tunnels into the wall of the blood vessel.
To minimize the . ' .'' effQct of recoil and the potential: " of ' ' injection, the catheter may be provided with a plurality of side holes (See, e.q. Fig. 5) to permit direct - between the central lumen and the outside of the catheter laterally through the wall of the catheter. Effluent flow of contrast media (or " in the case of a drug delivery catheter) through the side ports can be enhanced by ~ or, ~ flow through the distal opening of the catheter. Althouyh the provision of a F l cap 20 or other occlusion at the distal end of the central lumen will increase effluent flow through the side ports, any such cap will also prevent the ability to advance single lumen catheters over a ~uidewire as i5 presently favored in the clinical setting.
Thus, any of the catheters of the present invention may a '" 11~ be provided with a valve at or near the distal end of the catheter, such as the valve described in United States Patent No. 5,085,635 issued February 4, 1992 to Cragg, the entirety of the ~ d of which is ~ ~It~d herein by ~.. F~
For example, referrin~ to Figure 5, there is " al.id a distal end fragment of an elongate tubular catheter 70 having a valve 78 thereon. Tubular catheter body 70, in the " ~dll,d embodiment, is provided with a distal end segment 72 having a plurality of lateral apertures 74 thereon. A~ IU.t.~ 74 are placsd in fluid L
with an external proximal fluid source (not " ~ Ld) by way of axially extending central lumen 76.
Distal se~ment 72 is provided with a valve 78. In the " : dll.d; ' " t, valve 78 ~ three coaptive leaflets 8i3. Leaflets 80 r~, dle in a manner that will be well ~ d to those of skill in the art, to permit the passage of a ~ ' . ;.t: (not ." aLLd) ' . ' vh~ and resiliently return to a relatively closed r '~ aliu~ as i" : dtl,d, foliowing .: ' ~., dl of the guidewire. Leaflets 80 are, ~ from a relatively resilient material, to provide a bias to return to the closed s~ , the bias provided by leaflets 80 will be sufficient to - ' 'l~ resist the fluid pressure ~ luped in central lumen 76 during infusion of contrast media or . "

WO 97/17998 PC~US96/18227 upon the desired funrt ' t~! of the catheter, valve 78 may be c ~ u.,ted to substantialiy prohibit fluid fiow i' ~thl ~' Alll,.llali ~l~, valve 78 may be ~ ' to e~ ' le a relatively small fluid flow even in the "closed" position to prevent v i in the vessel at the distal end of the catheter as will be ' ~ vd to those of skili in the art.
Leaflets 80 can be ~ t -' in any of a variety of manners, such as by integral c ~" :- r with the wall of distal segment 72, or by separate rv. and subsequent di' ' ' to the distal segment 72. For example, leaflets 80 may be , dtel~ molded or punched from sheet stock of a - pr: ' ' material, such as a high density F 1~ 1e-.~" and i' ~drle. adhered to the distal segment 72 such as by thermal bonding, solvent bonding, adhesives, welding, or any of a variety of other ~ ' , known in the art. AIIL.~_~;.1Y, the polymer chosen for use as a valve can be molded as a tube ~ a closed septum. This molded unit can be heat fused or bonded onto the catheter tubin~. The septum can then be cut to produce the valve leaflet described, ~
The number of leaflets can be varied as desired to e - -~ td catheter design and 'al.ll.. ~ issues.
For example, a type of a two leaflet valve is " diLd in Figures 8 and 9. Four or more coaptive or r , dli..
leaflets can also be used.
A variety of alternate valve ~1. t.~ iS disclosed in Figures 6 13. The selection and r t.~."i ~ of a particular valve depends upon the desired l,hal aLl~ of the finished catheter. For example, in some 3~
it may be desirable to inhibit any fluid flow through the distal valve, or to permit a relatively small volume fluid flow i' ~i~ ,' All~ i. d~, it may be desirable to permit fluid flow in one direction and prevent or minimize fluid flow in the opposite direction. The desired direction of flow or inhibition of flow may be reversed ' . ' " upon whether the clinical objective is to infuse I ' i . or aspirate fluid from the lumen. ûther uses will su~gest i- ' . to those of skill in the art in view of the specific valve - bc disclosed below.
Referring to Figure 6, there is " t~di!r' a r, ~ y view of a distal end 82 of a I r i' - in d - with the present invention. A valve 84 is r --~ within central lumen 86. Valve 84 ;_~.s a membrane which may be formed integrally with or attached to the wall of catheter section 82. The, ' is provided with a central aperture 88 such as a 0.005 inch diameter opening, in a ~ ': having an outside diameter of about .026 inch. Aperture 88 permits the escape of p,l ,~ iL~d media, such as contrast media or . sufficient to create a fluid flow in cavity 90, which may exist ' ' " upon the c - of the catheter. In the absence of a sufficient flow through cavity 90, that cavity could provide the site for the r,, of a thrombus and ' , embolism with known .'~. ' sequela.
Aperture 88 may be sized to slidably receive a guidewire i ,:~ "' All~.llaii.. 1~, aperture 88 may have a smaller cross s : ' " ~ than the intended guidewire, but the valve 84 may be ~ : ' from a material having sufficient resilience to permit an elastic e r ~ of the aperture 88 to er~ ' the guidewire .. .. .
~ ., Referring to Fi~qure 8, there is disclosed an alternate - ~ l of a valve 90. Valve 90 is hu~t~d by providing a slit 92 through a valve ' ~, to provide first and second valve leaflets 94 and 96. Con~
of valve 90 from a relatively resilient material such as rr1~ I . and having a wall thickness of about .005 in., W O 97/17998 PCT~US96/18227 will permit sufficient elasticity for the leaflets 94 and 96 to return to the core group position followin~ removal of a g ' .O Ih~ ' \lalve 90 can also be ~ ' from any of a variety of I ' a, TPU, ~ ' , ' ~-rubber, or ' a~: rubber.
Referring to Figure 10, there is disclosed a valve 98 formed from a self-healing ' or plug F~
5 within the central lumen. In one ' -' t, valve 98 c ~ 3r a silicone gel plug attached at least one point 100 to the wall of the catheter. The silicone gel plug may be hinged about - ' I point 100 within the central lumen by ri : force, such as by a ~, ' .O~ and yet will return to occlude the central lumen upon removal of the g ' . ;~O. The silicone gel plug may be provided with an annular valve seat on the interior surface of the catheter body, as will be 3,,~..,;al~,d by those of skill in the art. i'r, ' ~, upon the desired direction of ..
10 to flow, the valve seat can be p ' on either the proximal or distal side of the gel plug.
A further; ' - ' : of a valve in ~ d with the present imlention is " dlL.d in Figure 12. Valve 102 is in the L Fi", of a generally conical or tapered duckbill valve. Duckbill valve 102 r i;,~s at least a first and second leaflet 104 and 106, inclining radially inwardly in the proximal direction in the " ~, ' ' -' Leaflets 104 and 106 as " ~,~,t.,;i permit a~- : of the catheter over a " ' . ;.e in the distal 15 direction, and, following proximal ~; ' ', al of the guidewire, will resist the escape of, i~od fluid out of the distal end of the catheter. In addition, duckbill valve 102 will permit the ~-, ai- of fluid, if desired, from the vessel into the cathQter.
Referring to Figure 14, there is " ~, ' an ' " n of the IhOIO~ of the present invention having a distal inflatable balloon thereon. The i' ~dll,d balloon catheter ' - ' of the present invention also 20 : - l ardlO5 a distal valve in the central lumen as discussed ",.: 1y. The r '~ of the valve with an inflatable balloon in the ~ s- ' of the present invention permits a i;al Ih,ulall~ small diameter catheter in view of the ability of the catheter to utiiize a sin~le central lumen for both r : of the catheter over a guidewire, and also as an inflation lumen for inflating the balloon.
The balloon catheter 108 generally s, iàcs an elongate flexible tubular body 110, which can be 25 !~ d in .' with any of a variety Of r ~, ' ' single lumen catheter body l~ ' , For example, body 110 can be formed by extrusion from high density pr~eth~ - or any of a variety of other well known catheter body - ~ ' F~or~ , the tubular body 110 is o ~,l l ' in --- d with one of the b~ ' : of the invention ",. '~ described herein. For the purpose of Figure 14, only the distal, balloon end of the catheter will be " al..d.
The distal end of catheter 110 is provided with an inflatable balloon 112. Balloon 112 is o ' to the catheter body 110 at a proximal seal 114 and a distal seal 116 as is known in the art, thereby creating an enclosed interior space 118. Interior space 118 is placed in fluid c with a proxirnal source of inflation media (not " Idt~..J by way of an elongate central lumen 120 which extends axially ~ the len~th of the catheter. Central lumen 120 is in fluid L ~ -- - with the interior 118 of balloon 112 by one or more inflation 35 side holes 122.

CA 02234706 l998-04-09 The . ~ material, axial length, as well as inflated diameter of the balloon 112, can be varied widely ,', ' " upon the intended clinical use, as is well ' ~ d in the art. In one preferred embodiment of the .. . the balloon 112~ sp~ ' f; ; ' such as Dow, Engage SM8400, and is ~ ~,. d to have an inflated profile with a diameter of about 4 mm at 0.5 ATM and an axial working length of about 1 cm. Other lengths and ~ , as well as other balloon r,ha.a~.lL.;~ can be readily ~ ~. dlad into the ~ ucai' : of the present i .. . as may be desired for a particular intended ~,, ' ~
The distal end 124 of tubular body 110 is provided with a valve 126. Valve 126 may be c~ ~al : ' in ~ ' - with any of the ~ ' - ' Is d;- uiso~, L. ~ herein. In one particular ~ of the i .. i valve 126~ tj a three leaflet c t,l as has been ' The valve 126 permits the catheter to be advanced over a ~ ' . :.~ such as during the p ~- " step as has been :' ' Followin~q p- ~ - - " of the balloon at the desired ll~ site, the g ' ;.~ may be ' 'r~. ., from central lumen 120. Valve 126 closes due to its inherent resilient ~ .. Thereafter, inflation media may be i..l-. ~ ' into the central lumen 120. Inflation media is inhibited from exiting the distal end of central lumen 120 by closed valve 126. Instead, the inflation media escapes central lumen 120 through side port 15 122, to inflate the interior 118 of balloon 112.
In the embodiment of the invention described below, the valve 126 inhibits or ~ 'l~ inhibits escape of inflation media up to an inflation pressure of about 7 di ,' ~... n -- to excessive leakage at higher inflation pressures can be achieved through - ' '; of the valve design, as will be readily apparent to those of skill in the art in view of the ~ ' e herein. For example, I - ~. the thickness of the valve leaflets, or 20 using a less flexible material for the valve leaflets will increase the break pressure of the valve 126. In addition, :,IIl,~,lL..dl I ' f, - can be made to the design of the valve 126 which will increase its break pressure.
In the ' - ~ " t,dl~d in Figure 14, a distal valve assembly 128 may be ~ t. : ' s~ from the tubular body 110, and secured thereto as a ' , I assembly step. Valve assembly 1Z8 can be G~ : L d in any of a variety of ways, such as by molding as an integral unit. In one I ~ " t, the valve assembiy 128 can be injection molded from polyolefin or r 1~ as a tubular ' - "~ having an axial length of about .20 inches an inside diameter of sbout .018 inches and an outside diameter of about .038 inches. The central lumen is blocked by a r ~ having a thickness of about .008 inches. The diaphra~m can be provided with three slits as a post molding step to produce a three leaflet valve 126.
The valve assembly 128 may i' ~ l,r be secured to the distal end of tubular body 110, such as by heat 30 fusing or bonding. As a further ll f~ . step, the distal seal 116 on balloon 112.~ .. 'ly extends axially a sufficient distance to overlap the junction between the distal end of tubular body 110 and the proximal end of valve assembly 128.
In r d ~~ with a method of the present invention, an i .... ' site is identified in a soft tissue such as the brain which requires dilatation to improve blood flow. A balloon ~ ~ ': 108 in ~ L with the present invention is r ~ d into the patient's vascular system and 1-_ ' ~ 'l~ advanced to the 1-1 site. F~ , the ~ '~. ,. and F~ ~ ~ steps of the method are 'h~rd throu~qh the use of WO 97/17998 PCTrUS96/18227 an elongate flexible ~ extending axially ll.. ~ the lenyth of the central lumen 120, as is well in the art.
Following p ~ of the balloon 112 at the ~ a; site, the 9 ' ;.~ is, I ~ 'l~ . ' 'r~ .. from the catheter. As the distal end of the " ' . ~ advances, 'I~ through valve 126, the valve leaflets move into 5 a closed position as has been ' Thereafter, inflation media is ~ ' into central lumen 120 at the desired pressure to inflate balloon 112. Durin~ inflation, the valve 126 prevents or ~ prevents the esGape of inflation media out the distal end of the catheter 108, thereby r~ " " dilatation of the balloon 112. ~p ' "
upon valve design, a small amount of inflation media may escape through the valve 126, if desired, to minimize the Da 11 a of stagnant blood in the distal tip of the balloon ~ ~ ': 108.
tO Following dilatation of balloon 112, inflation media is l,.;thd~.. from the balloon 112 by way of central lumen 120 as is known in the art to collapse the balloon 112. The balloon ~ :': 108 may then be , ~ ~ 'Iy withdrawn from the patient, and the patient is treated in ~r ,' a with ._ ' post dilatation , u~
Although the present invention has been described in terms of certain preferred ~ '-" other 15 . bc ' will become apparent to those of ordinary skill in the art followin~ a review of the di~.,lu;....t: herein.
A~'' - ' bc' that are apparent to those of skill in the art in view of this l" ' u are intended to be within the scope of the present invention, and the foregoing ~ is, thus, intended not by ' but merely to illustrata a specific a,, " i of the i .. The scope of the invention is intended to be defined by the scope of the _, h!d claims.

Claims

WHAT IS CLAIMED IS:

1. A catheter for negotiating small, tortuous vessels comprising:
an elongate flexible body having a tubular wall and at least one lumen extending axially therethrough;
a first tubular element in the wall, extending axially through the body and terminating in a first distal zone;
a second tubular element in the wall, extending axially through the body and terminating in a second distal zone;
wherein each of the first and second tubular elements is provided with a spiral cut in each of the first and second distal zones.

2. A catheter as in Claim 1, wherein the first tubular element is disposed coaxially within the second tubular element.

3. A catheter as in Claim 2, wherein the second distal zone is axially displaced from the first distal zone.

4. A catheter as in Claim 2, further comprising a spring coil coaxially disposed within the tubular wall.

5. A catheter as in Claim 4, wherein the spring coil is coaxially disposed on the radially exterior side of the first tubular element and on the radially interior side of the second tubular element.

6. A catheter as in Claim 5, further comprising an outer tubular sleeve surrounding the tubular wall.

7. A catheter as in Claim 6, further comprising a radiopaque marker disposed proximate the distal end thereof.

8. A catheter as in Claim 1, wherein said first tubular element comprises polytetrafluoroethylene and said second tubular element comprises polyimide.

9. A catheter as in Claim 4, wherein said spring coil comprises a proximal zone in which adjacent windings of coil are positioned in contact with each other, and a distal section in which adjacent windings of coil are spaced axially apart from each other.

10. A catheter as in Claim 4, wherein said spring coil comprises wire having a rectangular cross sectional configuration.

11. A method of manufacturing a highly flexible small diameter catheter, comprising the steps of:
providing an elongate first tubular element having a distal zone in which the tubular element is provided with a first spiral cut;
positioning a spring coil coaxially around the outside of the first tubular element, said spring coil extending distally from the proximal end of the catheter to a point spaced apart proximally from the distal end of the first tubular element;
providing a second tubular element having a proximal solid wall zone and a distal spiral cut zone;

positioning the second tubular element coaxially around the spring coil to produce a catheter subassembly, such that the second tubular element extends from the proximal end of the catheter to a point which is proximal to the distal end of said spring coil;
positioning an outer tubular jacket around the outside of the subassembly formed by said first and second tubular elements and said spring coil; and radially reducing the outer tubular jacket to form a highly flexible small diameter catheter.

12. A catheter, comprising:
an elongate flexible tubular body having proximal and distal ends, and at least one central lumen extending axially therethrough; and at least one flexibility gradient zone on the catheter body, said flexibility gradient zone having a first flexibility at a proximal end thereof, a second flexibility at a distal end thereof, and a continuous change in flexibility along the length of the zone from the first flexibility from the second flexibility.

13. A catheter as in Claim 12, wherein said flexibility zone extends for at least about 98% of the length of the catheter.

14. A catheter as in Claim 12, wherein said flexibility zone extends for at least about 75% of the length of the catheter.

15. A catheter as in Claim 12, wherein said tubular body has a wall thickness between an outside surface of the tubular body and the lumen extending therethrough, and the wall thickness at the proximal end of the flexibility zone is greater than the wall thickness at the distal end of the flexibility zone.

16. A catheter as in Claim 12, wherein said flex-ibility zone comprises a continuous change in wall thickness from the proximal end to the distal end thereof.

17. A catheter as in Claim 12, wherein said flex-ibility zone extends for at least about 148 cm, and has a wall thickness within the range of from about .009 inches to about .012 inches at the proximal end thereof and within the range of from about .0005 inches to about .002 inches at the distal end thereof.

18. A catheter as in Claim 1, said catheter having proximal and distal ends, and further comprising an inflatable balloon on the distal end thereof, said balloon in fluid communication with the lumen by way of at least one aperture in the tubular wall, and a valve in the central lumen, wherein said valve permits the passage of a guidewire through the central lumen, but closes following removal of the guidewire to permit introduction of pressurized media into the lumen to inflate the balloon.

19. A method of treating a vessel, comprising the steps of:
providing a catheter having an elongate flexible tubular body having a central lumen extending axially therethrough, a distal valve within the central lumen, and an inflatable balloon on the distal end of the tubular body in fluid communication with said central lumen proximally of said valve;
advancing a guidewire through the central lumen and through the valve;
positioning the guidewire end catheter within the vessel such that balloon is at a treatment site;
withdrawing the wire from the central lumen; and thereafter, inflation media into the central lumen to inflate the balloon;
wherein the valve moves into a closed position following removal of the guidewire from the central lumen to substantially prevent escape of inflation media through the valve.