Stent delivery catheter and method of making same

• US 20020138128A1
• Filed: 03/23/2001
• Published: 09/26/2002
• Est. Priority Date: 03/23/2001
• Status: Active Grant

• Current Assignee: Medtronic Ave Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Ave Incorporated (Medtronic Plc)
• Inventors: Stiger, Mark L., Mohn, Michael A., Hoekwater, Mark, Sobe, Lior
• Granted Patent: US 6,589,274 B2
• Time in Patent Office: Days
• US Class Current: 623/1.11
• CPC Class Codes: A61F 2/958 Inflatable balloons for placing stents or stent-grafts
• CPC Class Codes: A61F 2002/9583 Means for holding the stent on the balloon, e.g. using protrusions, adhesives or an outer sleeve

Abstract

A stent delivery catheter includes an extendable shaft portion, a tubular balloon mounted thereon, a stent and a pair of elastic retaining caps. The balloon is mounted onto the catheter at a mounted length that is shorter than the formed length of the balloon to generate excess balloon material which is gathered into circumferential folds. The extendable portion of the catheter shaft elongates in response to tension applied by the balloon as the folds open during inflation. Elongation of the catheter shaft drives the retaining caps apart to uncover the ends of the stent.

Claims

1. A stent delivery catheter comprising:

a catheter shaft having an inflation lumen therethrough and a longitudinally extendable portion at a distal end thereof;

an inflatable tubular balloon having first and second ends and a formed length, the balloon being mounted and wrapped around the catheter shaft surrounding the extendable portion thereof and in communication with the inflation lumen, the balloon having a mounted length that is shorter than the formed length such that excess balloon material develops during the mounting of the balloon on the catheter, the excess material forming at least one circumferential fold;

a balloon expandable stent having open ends, the stent being crimped about the balloon between the ends thereof; and

an elastic retention cap, the cap being fixed to the shaft adjacent the first end of the balloon, the cap extending over a portion of the balloon such that the cap lies over the stent end nearest the first end of the balloon.

2. The catheter of claim 1 wherein the balloon is inflatable from a first configuration wherein the cap lies over one end of the stent, to a second configuration wherein the at least one circumferential fold of the balloon is unfolded, the cap is longitudinally separated from the stent and the stent is expanded for deployment in a vessel of a patient.

3. The catheter of claim 2 wherein the balloon is deflatable from the second configuration to a third configuration wherein the balloon is substantially collapsed around the extendable portion of the catheter shaft, the cap lies substantially snugly about the first end of the balloon, and the balloon is separated from the expanded stent to allow removal of the catheter from the vessel while the expanded stent remains deployed in the vessel.

4. The catheter of claim 2 wherein the extendable portion of the catheter shaft has a first length corresponding to the first configuration of the balloon and the extendable portion has a second length corresponding to the second configuration of the balloon, the second length being longer than the first length.

5. The catheter of claim 4 wherein the extendable portion of the catheter shaft comprises a material that permits elongation thereof from the first length to the second length.

6. The catheter of claim 5 wherein the shaft material is a thermoplastic elastomer.

7. The catheter of claim 6 wherein the thermoplastic elastomer is a polyether block amide co-polymer.

8. The catheter of claim 1 wherein the retention cap is composed of an elastic material.

9. The catheter of claim 8 wherein the elastic material is a low durometer synthetic rubber.

10. The catheter of claim 1 wherein the retention cap end that lies over one end of the stent is partially embedded into the stent.

11. The catheter of claim 1 wherein the retention cap is fixed to a neck at the first end of the balloon, the neck being fixed to the shaft.

13. The catheter of claim 12 wherein the at least one circumferential fold comprises distal and proximal circumferential folds formed respectively beyond the distal and proximal ends of the stent.

14. The catheter of claim 13 wherein the distal and proximal caps cover respectively the distal and proximal circumferential folds.

15. The catheter of claim 14 wherein the catheter is transformable between a first configuration wherein the balloon is deflated and the distal and proximal caps lie respectively over the distal and proximal ends of the stent, and a second configuration wherein the balloon is inflated, the distal and proximal circumferential folds of the balloon are unfolded, the caps are longitudinally separated from the stent and the stent is expanded for deployment in a vessel of a patient.

16. The catheter of claim 15 wherein the catheter is transformable from the second configuration to a third configuration wherein the balloon is substantially collapsed around the catheter shaft, the distal and proximal caps lie substantially snugly about the ends of the balloon and the balloon is separated from the expanded stent.

18. The method of claim 17, further providing a second elastic retention cap having two ends, and installing the second cap such that one end of the second cap is fixed to the catheter shaft adjacent the second end of the balloon, and the other end of the second cap lies over the stent end located nearest the second end of the balloon.

19. The method of claim 17 wherein the balloon is capable of expanding the stent when the balloon is inflated with at least a selected pressure, and the at least one circumferential fold is capable of unfolding to cause elongation of the balloon during inflation thereof at approximately the selected pressure.

20. The method of claim 19 wherein the shaft portion is sufficiently extendable to accommodate the elongation of the balloon during inflation.

21. The method of claim 20 wherein the first retention cap is capable of longitudinal movement accompanying the extension of the extendable shaft portion.

12. A stent delivery catheter comprising:

a catheter shaft having an inflation lumen therethrough and a longitudinally extendable portion at a distal end thereof;

an inflatable tubular balloon having proximal and distal ends and a formed length, the balloon being mounted and wrapped around the catheter shaft surrounding the extendable portion thereof and in communication with the inflation lumen, the balloon having a mounted length that is shorter than the formed length such that excess balloon material that develops during the mounting of the balloon on the catheter forms at least one circumferential fold;

an expandable stent having proximal and distal ends, the stent being crimped about the balloon;

a distal elastic retention cap, the distal cap being fixed to the shaft adjacent the distal end of the balloon, the distal cap extending over the distal end of the balloon and the distal end of the stent; and

a proximal elastic retention cap, the proximal cap being fixed to the shaft adjacent the proximal end of the balloon, the proximal cap extending over the proximal end of the balloon and the proximal end of the stent.

17. A method of making a stent delivery catheter, comprising the steps of:

(a) providing an elongate catheter shaft having proximal and distal ends, an inflation lumen, and an extendable shaft portion adjacent the distal end;

(b) providing a tubular balloon having first and second ends and a length, and mounting the balloon around the extendable shaft portion such that at least one circumferential fold is formed in the balloon, the balloon being in fluid communication with the inflation lumen;

(c) deflating the balloon and wrapping wings formed thereby around the extendable shaft portion;

(d) providing an expandable stent having two open ends and a length that is shorter than the length of the balloon, and crimping the stent about the balloon, between the first and second ends thereof;

(e) providing a first elastic retention cap having two ends, and installing the first cap such that one end of the first cap is fixed to the catheter shaft adjacent the first end of the balloon, and the other end of the first cap lies over the stent end located nearest the first end of the balloon.

22. A method of deploying a stent in the vessel of a patient, comprising the steps of:

(a) providing an elongate, flexible catheter having a deformable inner shaft positioned within a lumen of an outer shaft to extend distally therefrom, further providing an inflatable tubular balloon, the balloon having proximal and distal ends and having proximal and distal circumferential folds and having a stent crimped thereon between the proximal and distal folds, the balloon distal end being bonded to the inner shaft and the balloon proximal end being bonded to the outer shaft, the balloon having a proximal cap bonded to the outer shaft adjacent the balloon proximal end and extending distally therefrom to cover the balloon proximal fold and to lie over the stent proximal end, the balloon having a distal cap bonded to the inner shaft adjacent the balloon distal end and extending proximally therefrom to cover the balloon distal fold and to lie over the stent distal end;

(b) positioning the balloon within a stenosis in a blood vessel of a patient;

(c) inflating the balloon from a first configuration, wherein the caps secure the stent to the balloon, to a second configuration, wherein the folds of the balloon unfold to longitudinally release the caps off of the stent, wherein the inner shaft elongates to accommodate the unfolding of the folds and wherein the stent has expanded against the blood vessel;

(d) deflating the balloon from the second configuration to a third configuration, wherein the balloon separates from the expanded stent and wherein the caps lie substantially against the balloon; and

(e) withdrawing the catheter from the vessel.