Stent installation method using balloon catheter having stepped compliance curve

• US 6,402,778 B2
• Filed: 01/31/2001
• Issued: 06/11/2002
• Est. Priority Date: 03/02/1995
• Status: Expired due to Term

• Current Assignee: Boston Scientific Scimed, Inc. (Boston Scientific Corporation)
• Original Assignee: Scimed Life Systems Incorporated (Boston Scientific Corporation)
• Inventors: Wang, Lixiao
• Primary Examiner(s): Milano, Michael J.
• Assistant Examiner(s): HO, TAN-UYEN THI
• Application Number:
  US09/774,725
• Publication Number:
  US 20010008976A1
• Time in Patent Office: 496 Days
• Field of Search: 623/1.1, 623/1-1-, 623/1.3, 623/1.31, 623/1.5, 623/1.51, 623/1.52, 623/1.53, 623/1.54, 606/191, 606/192, 606/194, 606/195
• US Class Current: 623/1.11
• CPC Class Codes: A61F 2/958 Inflatable balloons for placing stents or stent-grafts
• CPC Class Codes: A61F 2250/0039 differing in diameter
• CPC Class Codes: A61M 2025/1059 having different inflatable sections mainly depending on the response to the inflation pressure, e.g. due to different material properties
• CPC Class Codes: A61M 2025/1075 having a balloon composed of several layers, e.g. by coating or embedding
• CPC Class Codes: A61M 25/10 Balloon catheters A61M25/0125 takes precedence; embolectomy A61B17/22032; retractors A61B17/02; inflatable balloons for placing stents or stent-grafts A61F2/958 ; stomach balloons for treatment of obesity A61F5/0003; oesophagal tubes A61J15/00
• CPC Class Codes: A61M 25/1002 characterised by balloon shape A61M25/1006, A61M25/1009 take precedence
• CPC Class Codes: A61M 25/1029 Production methods of the balloon members, e.g. blow-moulding, extruding, deposition or by wrapping a plurality of layers of balloon material around a mandril
• CPC Class Codes: A61M 25/104 used for angioplasty

Abstract

A method for installing a stent in a vessel utilizes a single balloon catheter for both low pressure predilation at a relatively small diameter to open the lesion sufficiently to allow insertion and deployment of the stent across the lesion and for subsequent high pressure embedding of the stent in the vessel wall. The same balloon catheter may also be employed to insert and deploy the stent. The balloons utilized in the method have a stepped compliance curve which allows for predilation at a low pressure and predetermined diameter and for high pressure embedding at a substantially larger diameter. The balloons may be provided with a configuration in which only a portion of the balloon has a stepped compliance curve while a further portion has a generally linear compliance profile. With such balloons high pressure treatment of the vessel wall areas not reinforced by the stent can be avoided despite the occurence of longitudinal shrinkage of the stent during expansion thereof.

Claims

1. An assembly comprising:

a) a catheter having a distal end;

b) an unexpanded inflatable balloon mounted near the distal end of the catheter, the balloon having first and second end regions adhered to the catheter and an inflatable balloon body there between; and

c) a hollow expandable stent having an initial stent diameter, an initial stent length and a pair of ends, the stent being mounted on the catheter over the balloon, the stent being expandable by the balloon to a second stent diameter larger than the initial diameter, the stent initial length shortening during expansion so that at said second stent diameter the stent has a second stent length shorter than said first stent length, and

the balloon, when inflated at an effective inflation pressure effective to cause the stent to expand to said second diameter, has

first and second adjacent longitudinal stepped body portions with different diameters, the second stepped body portion diameter being greater than the first body portion diameter and having a length and position such that it does not extend beyond the ends of the stent at said second stent diameter,

a first tapered diameter transition region extending from said first end region to said first stepped body portion,

a second tapered transition region extending between said first and second stepped body portion and

a third tapered transition region extending between the second stepped body portion and the second end region.

2. An assembly as in claim 1 wherein the second stepped body portion, when the balloon is inflated at said effective pressure, has a length and position such that it does not extend beyond the ends of the stent at said second stent diameter.

3. An assembly as in claim 2 wherein the stent initial length shortens during expansion so that at said second stent diameter the stent has a second stent length shorter than said first stent length.

4. An assembly as in claim 1 wherein the balloon is made of a thermoplastic polymer selected from the group consisting of polyesters, nylons, thermoplastic polyimides and thermoplastic polyurethanes.

5. An assembly as in claim 4 wherein the balloon is made of a polyester selected from poly(ethylene terephthalate) and poly(ethylene napthalenedicarboxylate).

6. An assembly as in claim 1 having a burst pressure of greater than 15 atm and a compliance curve according to which the balloon expands at a rate of no more than 0.1 mm/atm from 15 atm to burst.

7. An assembly as in claim 5 wherein the balloon wherein according to said compliance curve the balloon expands at a rate no more than is no more than 0.06 mm/atm from 15 atm to burst.

8. An assembly as in claim 1 wherein the balloon is mounted on the catheter such that the balloon second stepped body portion is distal to the first stepped body portion.

9. An assembly as in claim 1 wherein the balloon is mounted on the catheter such that the balloon second stepped body portion is proximal to the first stepped body portion.

10. The method for introducing a stent into a vessel at a lesion site, the method comprising the steps of:

introducing into the vessel an assembly as in claim 1 and manipulating the assembly so that the stent crosses the lesion, and subsequently

inflating the balloon to an effective pressure whereby the stent is expanded to a second stent diameter.

11. The method as set forth in claim 10 wherein the balloon is made of a thermoplastic polymer selected from the group consisting of polyesters, nylons, thermoplastic polyimides and thermoplastic polyurethanes.

12. A method as set forth in claim 11 wherein the balloon is made of a polyester selected poly(ethylene terephthalate) and poly(ethylene napthalenedicarboxylate).

14. An assembly as in claim 4 wherein the balloon is made of a thermoplastic polymer selected from the group consisting of polyesters, nylons, thermoplastic polyimides and thermoplastic polyurethanes.

13. An assembly comprising:

a) a catheter having a distal end;

b) an unexpanded inflatable balloon mounted near the distal end of the catheter; and

c) a hollow expandable stent having an initial stent diameter, an initial stent length and a pair of ends, the stent being mounted on the catheter over the balloon, the stent being expandable by the balloon to a second stent diameter larger than the initial diameter,

wherein

the balloon has been molded in a configuration providing adjacent first, second and third stepped longitudinal body portions of the body with different diameters, the second stepped body portion diameter being greater than the first and third stepped body portions,

the stent located such that the balloon second longitudinal stepped body portion, when the balloon is pressurized at an effective inflation pressure, expands the stent to said expanded stent diameter, and

the balloon first stepped portion, when the balloon is pressurized at said effective inflation pressure has a diameter less than the diameter of the balloon second stepped portion.

15. A method for introducing a stent into a vessel at a lesion site, the method comprising the steps of:

introducing into the vessel an assembly as in claim 13 and manipulating the assembly so that the stent crosses the lesion, and subsequently

inflating the balloon to an effective pressure whereby the stent is expanded to an expanded stent diameter.