US20060206190A1 - Balloon catheter for multiple adjustable-length stent deployment - Google Patents

Abstract

A catheter configured to carry one or more stents and having an inflatable balloon for expanding a stent surrounding the balloon. The catheter is characterized in having a positioner for moving the one or more stents relative to the balloon from a first position in which the stent does not surround the balloon to a second position in which the stent surround the balloon. Also disclosed is a method for deploying a stent at a desired location in the vascular system.

Description

RELATED APPLICATION DATA
• This application is a continuation of U.S. patent application Ser. No. 10/108,985, filed Mar. 29, 2002, which application is hereby incorporated by reference in its entirety.
FIELD OF THE INVENTION
• This invention relates to catheters and more specifically to such catheters that are used to implant a stent in an artery.
BACKGROUND OF THE INVENTION
• Blood vessels, and particularly arteries, may become stenotic or occluded due to various atherosclerotic processes. A stenotic artery may be treated by balloon angioplasty in which an inflatable balloon mounted on a catheter tip is inserted into the arterial system and navigated through the arterial system to the diseased artery. The balloon is then inflated by means of a pressurized fluid. This causes the balloon to press radially on the arterial wall so as to open the stenosis. A stent may be crimped onto the balloon before insertion so that when the balloon is inflated the stent becomes expanded, The balloon is deflated and withdrawn leaving the expanded stent in the artery. These and other similar methods are well known to the skilled man of the art.
• It is often necessary to treat several stenoses in a single angioplastic session. For example, it may be necessary to insert a large diameter stent at one location, a small diameter stent at a second location and to perform a balloon angioplasty without a stent at a third location. This could be accomplished by sequential insertion and withdrawal of a catheter, the catheter being loaded each time with the appropriate stent prior to insertion. This however would cause much discomfort to the patient, prolongs the duration of the procedure and increases the chances of damaging a blood vessel.
• U.S. Pat. No. 6,027,519 discloses a catheter for deploying one or more stents. The stent has one or more individually expandable segments along its length. A stent, in its unexpanded states is loaded onto each expandable segment of the catheter. The catheter is inserted into the vascular system and positioned with the first expandable segment in a stenosis. An axial force is then applied to the segment causing it to buckle outwards and expand the stent. The force is then removed caused the segment to unbuckle leaving the stent in its expanded state. The catheter is then navigated to another stenosis. This process is repeated until all of the stents have been deployed.
SUMMARY OF THE INVENTION
• The present invention provides a catheter for deploying one or more stents in a cardiovascular system. The catheter is configured to carry one or more stents. Preferably, the catheter carries a plurality of stents. The stents may be of different or the same widths. An inflatable balloon is used to expand a stent surrounding the balloon. The catheter comprises a positioner for moving a stent relative to the balloon from a position in which the stent does not surround the balloon to a position that it does surround the balloon in order to prime the stent for expansion by the balloon. The phrase “for moving a stent relative to the balloon” includes two possibilities, i.e. moving the positioner relative to the balloon and moving the balloon relative to the positioner.
• In one embodiment of the invention the positioner comprises an element configured to slide along the catheter and push the stents distally along the catheter so as to move a stent adjacent to the balloon into a position in which it surrounds the balloon. The sliding element is pushed along the catheter by means of a wire extending along the catheter from its proximal end to the sliding element. In this embodiment, the stems are deployed in the order in which they are carried by the catheter, starting with the stent closest to the balloon.
• In another embodiment, the positioner comprises a flexible carriage configured to carry the one or more stents. The carriage is capable of sliding along the catheter in order to bring one of the stents from a position in which the stent does not surround the balloon to a position in which the stent surrounds the balloon. The carriage is moved in either direction along the catheter by means of a wire extending along the catheter from its proximal end to the carriage. It is also possible to position the stent opposite a desired location in the vascular system and slide the balloon through the carriage to a position opposite the stent. In this embodiment the stents may be deployed in the vascular system in any order.
• It a third embodiment, the catheter comprises two positioners, one posterior positioner as described above in the first embodiment positioned posterior to the balloon, and a second anterior positioner positioned anterior to the balloon. In this embodiment, the anterior positioner may be distanced from the balloon so as to provide a storage space between the anterior positioner and the balloon. The balloon in this embodiment may be a conventional balloon used in balloon angioplasty. In this embodiment also, the stents may be deployed in the vascular system in any order, and may be of different lengths.
• In use, the catheter is loaded with one or more stents and inserted into a vascular system. The catheter is navigated through the vascular system until the balloon or stent is positioned at a first desired location, typically the site of a stenosis. The stent or balloon is then moved by the positioner so that the stent surrounds the balloon and the balloon is inflated so as to expand the stent. The balloon is then deflated, leaving the expanded stent at the fist desired location. This process may be repeated, each time deploying a different stent at a different location. After one or more of the stents have been deployed, the catheter may be removed from the vascular system.
• The invention also provides a method for deploying a stent in a desired location of a vascular system comprising the steps of:
• (a) inserting a catheter according to the invention carrying one or more stents into the vascular system,
• (b) navigating the catheter through the vascular system until the balloon is positioned in the desired location;
• (c) moving a stent from a first position in which it does not surround the balloon to a second position in which it surrounds the balloon;
• (d) inflating the balloon so as to expand the stent; and
• (e) deflating the balloon.
BRIEF DESCRIPTION OF THE DRAWINGS
• In order to understand the invention and to see how it may be carried out in practice, a preferred embodiment will now be described, by way of non-limiting examples only, with reference to the accompanying drawings, in which:
• FIG. 1 shows a catheter in accordance with one embodiment of the invention;
• FIG. 2 shows the catheter ofFIG. 1 carrying stents;
• FIG. 3 shows the catheter atFIG. 1 inserted in a blood vessel;
• FIG. 4 shows the catheter ofFIG. 1 with a stent surrounding a balloon on the catheter;
• FIG. 5 shows the catheter inFIG. 1 after inflation of the balloon;
• FIG. 6 shows a catheter in accordance with another embodiment of the invention;
• FIG. 7 shows the catheter ofFIG. 6 carrying stents;
• FIG. 8 shows the catheter atFIG. 6 inserted in a blood vessel;
• FIG. 9 shows the catheter ofFIG. 6 with a stent surrounding a balloon on the catheter;
• FIG. 10 shows the catheter inFIG. 6 after inflation of the balloon;
• FIG. 11 is a sectional side view of a catheter in accordance with another embodiment of the invention;
• FIG. 12 illustrates the operation of the embodiment illustrated inFIG. 11; and
• FIG. 13 illustrates another detail of the operation of the embodiment ofFIG. 11.
DETAILED DESCRIPTION OF THE INVENTIONEXAMPLE I
• FIG. 1 shows acatheter100 for deploying stents in accordance with one embodiment of the invention. Thecatheter100 has adistal end108 and aproximal end120. Thecatheter100 comprises aflexible tube102, which is connected to aninflatable balloon104 proximate to its distal end. Theballoon104 is shown in the Figure in its deflated state. A radio-opaque marker118 is located on the balloon wall. Thecatheter100 has at its distal end108 a taperedtip110 that may be inserted into a stenosis in order to open the stenosis. Asyringe130 may be used to introduce a fluid into thetube102 in order to inflate theballoon104 as described in detail below.
• Alongitudinal shaft124 in the wall of thetube102 is configured to receive aguidewire126 used in navigating the catheter in the vascular system. Aneck region122 of thetube102 intervenes between the distal end of theballoon104 and thetip110. The proximal end of thetip110 is broadened to form a shoulder at the distal end of theneck region122. A sliding positioner element in the form of an annular slidingring114 is mounted on thetube102 proximal to theballoon104. Thering114 is slidable along thetube102 by means of awire116 that extends along the length of thetube102 from theproximal end120 of the catheter to thering114.
• The slidingring114 and thewire116 form a positioner for moving a stent from a position which it does not surround theballoon104 to a position in which it surrounds theballoon104.
• FIG. 2 shows thecatheter100 having a plurality of stents (three are shown inFIG. 2)206a,206band206c,mounted on thetube102 between the slidingring114 and theballoon104. The stents are separated from each other by separatingrings208aand208b.The slidingring114 has been positioned so that the separating rings208aand208band the stent206 are contiguous with theballoon104. Each stent206 bears a radio-opaque markers210a,210band210c.
• In use, thecatheter100 is introduced into the vascular system and navigated to a stenosis by methods well known in the art.FIG. 3 shows thecatheter100 after having been navigated through the vascular system and positioned inside ablood vessel202. The balloon is located opposite astenotic region204 of theblood vessel202. Thewire116 is used to slide the slidingring114 distally along thetube102 so as to push thestents206a,2066,206c,distally. The slidingring114 is pushed distally along thetube102 so that thestent206ais pushed over and around theballoon104, which is thereby brought into the lumen of thestent206a,and themarker118 on the balloon coincides with themarker210aof the stent, as determined for example by x-ray angiography.FIG. 4 shows thestent206asurrounding theballoon104.
• A fluid is then introduced into thetube102. The fluid passes through thetube102 and inflates theballoon104. It will be understood that the balloon may be inflated by other conventional means, as are known in the art. Inflation of theballoon104 expands thestent206aonto the stenotic region of theblood vessel202, as shown inFIG. 5.
• The fluid is then withdrawn from thetube102. Withdrawal of the fluid from thetube102 causes the balloon to deflate. After deflation of the balloon, thestent206aremains in situ in its expanded state.
• The catheter may then be navigated through the arterial system until the catheter is positioned with theballoon104 at. another stenotic region of a blood vessel. The sliding ring is pushed distally by thewire116 so that the succeedingstent206boverlies theballoon104 and themarker118 coincides with themarker210bon thestent206b.Thedistal separating ring208ais pushed along thetube102, beyond theballoon104 to theneck region122 of the tube, where the separating rings are stored. The shoulder of thetip110 retains the separating rings on the neck region. This process may be repeated until some or all of the stents206 have been deployed. The catheter is then removed from the body.
EXAMPLE II
• FIG. 6 shows acatheter600 for deploying stents in accordance with another embodiment of the invention. The embodiment ofFIG. 6 has many components in common with the embodiment ofFIG. 1, and similar components are identified by the same reference numeral in both embodiments.
• The embodiment ofFIG. 6 has acylindrical carriage605 mounted on thetube102. The carriage has a plurality of annular depressions (three are shown inFIG. 6)610a,610band610cconfigured to receive a stent as described below. The depressions610 all have the same length A as indicated inFIG. 6, which is essentially equal to the length of theballoon104. Between the depressions610 arebarriers620aand620b.Thecarriage605 is made from an elastic material such as rubber. Thecarriage605 is slidable along thetube102 by means of awire116 that extends along the length of thetube102 from theproximal end120 of the catheter to thecarriage605. Thecarriage605 and thewire116 form a positioner for moving a stent from a position in which it does not surround theballoon104 to a position in which it surrounds theballoon104.
• FIG. 7 shows thecatheter600 having a plurality of stents (three are shown inFIG. 7)206a,2066 and206cmounted on the annular depressions of thetube102. The stents are separated from each other by thebarriers620aand620b.In the present embodiment the stents are of different lengths. However, they may also be of the same length. Each stent206 bears a radio-opaqueannular marker210a,2106 and210c.
• Thecatheter600 is introduced into the vascular system and navigated to a stenosis by methods well known in the art.FIG. 8 shows thecatheter600 after having been navigated through the vascular system and positioned inside ablood vessel202. The balloon is located within astenotic region204 of theblood vessel202. Thewire116 is used to slide thecage605 distally along thetube102 so as to move the stents206 distally. Thecarriage605 is pushed distally along thetube102 until theballoon104 is brought into the lumen of thestent206aand themarker118 on the tube coincides with themarker210a,as determined for example by x-ray angiography. In a similar manner, the balloon may be slid within the carriage until it is positioned opposite the stent.FIG. 9 shows thestent206asurrounding theballoon104.
• A fluid is then introduced into thetube102. The fluid passes through thetube102 and inflates theballoon104. Inflation of thetube104 expands the portion of thecarriage605 surrounding theballoon104 which in turn expands thestent206aonto the stenotic region of theblood vessel202, as shown inFIG. 10.
• The fluid is then withdrawn from thetube102 into thesyringe130. Withdrawal of the fluid from thetube102 causes the balloon to deflate. After deflation of the balloon, thestent206aremains in its expanded state.
• The catheter is then navigated through the arterial system until the catheter is positioned with theballoon104 in another stenotic region of a blood vessel. The catheter is then pushed distally by thewire116 so that thestent206boverlies theballoon104 and themarker118 coincides with themarker210bon thestent206b.In this embodiment, the stents may be deployed in any order. This process may be repeated until some or all of the stents206 have been deployed. The catheter is then removed from the body.
EXAMPLE III
• This example illustrates an embodiment which is an improvement over the embodiment described in Example I. With reference toFIG. 11, there is shown acatheter700 having adistal end108 and aproximal end120. As inFIG. 1, thecatheter700 comprises aflexible tube102, which is connected to aninflatable balloon704 proximate to its distal end. A radio-opaque marker118 is located on the balloon wall. Thecatheter700 has at its distal end108 a taperedtip110, but unlike in Example I, there is no neck region, and the tip is not enlarged. The balloon in this embodiment may be a conventional inflatable balloon used in balloon angioplasty.
• As in Example I, aguidewire126 extends along thetube102, exiting at thedistal end108 of the catheter. An anterior positioner in the form of aperforated sphere706 is fixed to the guidewire anterior to theballoon704, e.g. the guidewire passes through a bore channel extending through the sphere. The diameter of the sphere is slightly larger than the diameter of the retracted stents which are mounted on the catheter. The purpose of the sphere will be explained below.
• Thecatheter700 has a slicing ring114 (being the posterior positioner) and a plurality of stents (three are shown inFIG. 11)206a,2066 and206c,mounted on thetube102 between the slidingring114 and theballoon704. While the anterior stents are generally of the same length, the posterior stent may be longer or shorter. In the illustrated embodiment, theposterior stent206cis shorter than the other stents. Each stent206 bears at least one radio-opaque marker210a,2106 and210c,respectively. The stents are separated by separatingrings708aand708bwhich are of the same length as the anterior stents. Ananterior ring710 is positioned between the mostanterior stent206aand theballoon704 and protects the distal edge of the anterior stent. This anterior ring may be shorter than the separating rings.
• The operation of this embodiment may be under-stood with reference toFIG. 12. As in Example I, thewire116 is used to slide the slidingring114 distally along thetube102 so as to push thestents206a,206b,206c,distally. Thesphere706 is distanced from thedistal end108 of the catheter by pushing theguidewire126, thus providingfree guidewire712 on which components of the catheter may be stored. InFIG. 12, it may be seen that theanterior ring710 and theseparating ring708ahave been pushed beyond theballoon704 and onto thefree guidewire712. Theanterior stent206a(not shown) has been expanded and deployed within the blood vessel wall, and the middle stent2066 is mounted on theballoon704, ready to be expanded. The radio-opaque marker210bof thestent206bis positioned opposite the radio-opaque marker118 of theballoon704.
• Thus, this embodiment also differs from that of Example I in having more room to store the separating rings. In addition, all of the mounted stents and rings may be moved distally and proximally by pulling and pushing the anterior and posterior positioners, being thesphere706 and slidingring114, respectively, so that the stents may be deployed in any order. This differs from Example I where the stents were required to be deployed in the order in which they were placed on the catheter.
• FIG. 13 shows the catheter after the2anterior stents206aand2066 (not shown) have been deployed, and the anterior710 and separating708a&7086 rings are positioned on thefree guidewire712 between thesphere706 and theballoon704. It may be seen that the separating rings haveannular protrusions714 protruding from their outer surface. The purpose of these protrusions is to protect the blood vessel inner wall from being injured by the stents as the catheter travels through the vessel. Theposterior stent206cis mounted on the distal half of theballoon704, while the anterior portion of the slidingring114 envelops the proximal end of the balloon. Thus, when the balloon is inflated, only the distal half expands (since the sliding ring resists the pressure of the balloon), expanding thestent206cand deploying it in the blood vessel.

Claims (21)

1. A stent delivery system comprising:

a catheter having a distal end and an inflatable balloon near the distal end for expanding a stent surrounding the balloon, the catheter carrying a plurality of stents and having a positioner slidable longitudinally along the catheter independently of said plurality of stents for moving said plurality of stents relative to said balloon from a first position proximal to the distal end to a second position closer to the distal end in which at least one of said plurality of stents surrounds the balloon,

the stents being independently deployable from each other such that the at least one stent may be expanded by the balloon while at least a second stent is retained on the catheter,

the catheter further having a separating member adapted to separate the at least one stent from the second stent to allow expansion of the at least one stent.

2. The stent delivery system according toclaim 1 wherein the stents are adapted to be deployed in a blood vessel in any order.

3. The stent delivery system according toclaim 1 wherein the positioner comprises a sliding element configured to slide longitudinally along the catheter and push the plurality of stents distally along the catheter so as to move a stent adjacent to the balloon into a position in which it surrounds the balloon.

4. The stent delivery system according toclaim 3 wherein the sliding element is attached to a wire extending longitudinally along the length of the catheter and the sliding element slides along the catheter in response to a longitudinal movement of the wire.

5. The stent delivery system according toclaim 1 comprising two positioners, a posterior positioner positioned posterior to the balloon and an anterior positioner positioned anterior to the balloon.

6. The stent delivery system according toclaim 5 wherein said anterior positioner is adapted to be distanced from the balloon so as to provide a storage space between the anterior positioner and the balloon.

7. The stent delivery system according toclaim 1 wherein said balloon has an expandable portion having a length that is adjustable to be coextensive with the length of the at least one of said plurality of stents.

8. The stent delivery system according toclaim 1, wherein the length of said at least one of said plurality of stents is different than at least one other of said plurality of stents.

9. A stent delivery system comprising:

a catheter having a distal end and an inflatable balloon near the distal end for expanding a stent surrounding the balloon, the catheter carrying a plurality of stents and having a positioner slidable longitudinally along the catheter and adapted to engage only a proximal stent of said plurality of stents to move said plurality of stents relative to said balloon from a first position proximal to the distal end to a second position closer to the distal end in which at least one of said plurality of stents surrounds the balloon for deployment therefrom,

the stents being independently deployable from each other such that the at least one stent may be expanded by the balloon while at least a second stent is retained on the catheter,

the catheter further having a separating member adapted to separate the at least one stent from the second stent to allow expansion of the at least one stent.

10. The stent delivery system according toclaim 9, wherein the stents are adapted to be deployed in a blood vessel in any order.

11. The stent delivery system according toclaim 9, wherein the positioner comprises a sliding element configured to slide longitudinally along the catheter and push the plurality of stents distally along the catheter so as to move said plurality of stents from the first position to the second position.

12. The stent delivery system according toclaim 11, wherein the sliding element is attached to an elongated member extending longitudinally along the length of the catheter and the sliding element slides along the catheter in response to a longitudinal movement of the elongated member.

13. The stent delivery system according toclaim 9, wherein said balloon has an expandable portion having a length that is adjustable to be coextensive with the length of the at least one of said plurality of stents.

14. The stent delivery system according toclaim 9, wherein the length of said at least on of said plurality of stents is different than at least one other of said plurality of stents.

15. The stent delivery system ofclaim 9, wherein the length of the stent deployed by the catheter is selectable.

16. A stent delivery system comprising:

a catheter having a distal end and an inflatable balloon near the distal end for expanding a stent surrounding the balloon, the catheter carrying a plurality of stents and having a positioner slidable longitudinally along the catheter for moving said plurality of stents relative to said balloon from a first position proximal to the distal end to a second position closer to the distal end in which at least one of said plurality of stents surrounds an expandable portion of the balloon,

the stents being independently deployable from each other such that the at least one stent may be expanded by the balloon while at least a second stent is retained on the catheter,

the catheter further having a separating member adapted to separate the at least one stent from the second stent to allow expansion of the at least one stent,

wherein the length of the expandable portion is adjustable to be generally coextensive with the length of the at least one stent.

17. The stent delivery system according toclaim 16 wherein the stents are adapted to be deployed in a blood vessel in any order.

18. The stent delivery system according toclaim 16 wherein the positioner comprises a sliding element configured to slide longitudinally along the catheter and push the plurality of stents distally along the catheter so as to move a stent adjacent to the balloon into a position in which it surrounds the balloon.

19. The stent delivery system according toclaim 18 wherein the sliding element is attached to an elongated member extending longitudinally along the length of the catheter and the sliding element slides along the catheter in response to a longitudinal movement of the elongated member.

20. The stent delivery system according toclaim 16, wherein the length of said at least one of said plurality of stents is different than at least one other of said plurality of stents.

21. The stent delivery system according toclaim 16, further comprising a constraining member slidable over said balloon, wherein the constraining member constrains a portion of the balloon from expanding.

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