AU2006202935B2

AU2006202935B2 - Two balloon staged stent expansion

Info

Publication number: AU2006202935B2
Application number: AU2006202935A
Authority: AU
Inventors: Jacob Richter
Original assignee: Medinol Ltd
Current assignee: Medinol Ltd
Priority date: 2000-06-14
Filing date: 2006-07-07
Publication date: 2008-11-13
Anticipated expiration: 2021-06-13
Also published as: AU2006202935A1

Description

AUSTRALIA

PATENTS ACT 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT

ORIGINAL

Name of Applicant: Actual Inventor: Medinol Ltd Jacob Richter Address of Service is:: SHELSTON IP Margaret Street SYDNEY NSW 2000 CCN: 3710000352 Attorney Code: SW Telephone No: Facsimile No.

(02) 9777 1111 (02) 9241 4666 Invention Title: TWO BALLOON STAGED STENT EXPANSION Details of Original Application No. 2001274463 dated 13 June 2001 The following statement is a full description of this invention, including the best method of performing it known to me/us:- 00 -2- O TWO BALLOON STAGED STENT EXPANSION t", SFIELD OF THE INVENTION The present invention relates generally to catheter balloons for implanting stents.

More particularly, the present invention relates to a catheter balloon which utilizes two t balloons coaxially disposed within one another.

t", BACKGROUND OF THE INVENTION Any discussion of the prior art throughout the specification should in no way be 10 considered as an admission that such prior art is widely known or forms part of common general knowledge in the field.

It is well known to use a balloon catheter to intraluminally deliver and implant a stent. Typically, to implant a stent with a balloon catheter, the unexpanded stent is disposed around the deflated balloon of a balloon catheter. The balloon is then delivered to the desired implantation site and inflated. The inflation of the balloon expands the stent, implanting it at the desired location.

One shortcoming of conventional balloon catheters is that they may cause the ends of the stent to flare out during implantation. This flaring out is referred to as "dogboning". Dogboning causes at least two undesirable effects. First, dogboning exacerbates any foreshortening of the stent during expansion. Second, dogboning causes the edges of the end of the stent to project in a direction perpendicular to the wall of the vessel in which the stent is being implanted. These projecting edges potentially increase trauma to the wall of the lumen.

It is an object of the present invention to overcome or ameliorate at least one of the disadvantages of the prior art, or to provide a useful alternative.

SUMMARY OF THE INVENTION According to a first aspect of the invention there is provided a stent and balloon catheter in combination comprising: a balloon catheter with an inner and an outer balloon, the outer balloon overlaying the inner balloon; and an expandable stent mounted over the inner and outer catheter balloons, 00 -3- O wherein: a burst pressure of the inner balloon is less than a burst pressure of the outer balloon, a length of the outer balloon is greater than a length of the stent and a length of the inner balloon is less than the length of the stent; and the burst pressure of the inner balloon being such that, when inflated with a pressurized medium it will expand sufficiently to expand the middle portion of the stent Sand implant the stent.

SAccording to a second aspect of the invention there is provided a stent and Iballoon catheter in combination comprising: a balloon catheter with an inner and an outer balloon, the outer balloon overlaying the inner balloon, both the inner balloon and the outer balloon sealed to a catheter shaft at each end; an inflation lumen in the catheter shaft in communication only with an interior of the inner balloon; and an expandable stent mounted over the first and second catheter balloons, wherein: a burst pressure of the inner balloon is less than a burst pressure of the outer balloon, a length of the outer balloon is greater than a length of the stent and a length of the inner balloon is less than the length of the stent; the burst pressure of the inner balloon is such that, when inflated with a pressurized medium from the inflation lumen, it will expand sufficiently to expand the middle portion of the stent and implant the stent, before bursting; and pressurized medium from the inflation lumen can enter the interior of the outer balloon to inflate it and further expand the stent over its full length only after the inner balloon bursts.

According to a third aspect of the invention there is provided a method of implanting a stent mounted on a balloon catheter with an outer balloon and an inner balloon, the outer balloon overlaying the inner balloon, a burst pressure of the inner balloon being substantially less than a burst pressure of the outer balloon, the method comprising the steps of: delivering the balloon catheter and stent to a desired location in a vessel in a body; 00 -4- O inflating the inner balloon to a pressure sufficient to expand a central portion of the stent; continuing inflating the inner balloon to a pressure sufficient to burst the inner balloon; inflating the outer balloon to a pressure sufficient to impact the stent; and t deflating and removing the balloon catheter.

SAccording to another aspect of the invention there is provided a method of

\O

implanting a stent mounted on a balloon catheter with an outer balloon with a length longer than the stent and an inner balloon with a length shorter than the stent, the outer balloon overlaying the inner balloon, a burst pressure of the inner balloon being substantially less than a burst pressure of the outer balloon, the method comprising the steps of: delivering the balloon catheter and stent to a desired location in a vessel in a body; inflating the inner balloon to a pressure sufficient to expand the stent; continuing inflating the inner balloon to a pressure sufficient to burst the inner balloon; inflating the outer balloon to a pressure sufficient to implant the stent; and deflating and removing the balloon catheter.

Unless the context clearly requires otherwise, throughout the description and the claims, the words 'comprise', 'comprising', and the like are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense; that is to say, in the sense of "including, but not limited to".

To implant the stent, the catheter is delivered to a desired site in a vessel.

Pressure is applied to the inner balloon, inflating the balloon and implanting the central portion of the stent. Further increases in pressure rupture the inner balloon. Because the outer balloon overlays the inner balloon, the pressure inflates the outer balloon, expanding the remainder of the stent. The balloons may then be deflated and removed, leaving the implanted stent in the vessel.

BRIEF DESCRIPTION OF THE DRAWINGS A preferred embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings in which: 00 Fig. 1 shows a cross-sectional view of an embodiment ofa catheter balloon assembly constructed according to the principles of the present invention which is in the deflated condition; Fig. 2 shows a cross-sectional view of the catheter of Fig. 1 after partial inflation; and Fig. 3 shows a cross-sectional view of the catheter of Fig. 1 after full inflation.

C DETAILED DESCRIPTION OF THE INVENTION Fig. 1 shows a schematic view of an embodiment of a catheter balloon constructed 10 in accordance with the principles of the present invention. The details of the catheter have not been included here, as they are well known to those skilled in the art. The precise configurations of the catheter shaft, guidewire lumen, and inflation lumen can be chosen as desired. For example, the catheter may be designed as a rapid-exchange system or as an over-the-wire system. The balloon catheter includes a catheter shaft 2.

An inner balloon 6 is sealed to the outer surface 4 of the catheter shaft 2. The length of the inner balloon is chosen so that it is less than the length of the stent which it is designed to implant. The inner balloon 6 may be formed of a non-compliant material.

An outer balloon 8 is disposed around the inner balloon 6. The inner surface of the outer balloon is immediately adjacent to the outer surface of the inner balloon.

The two surfaces are permitted to move with respect to each other. The outer balloon 8 is sealed to the outer surface 4 of the catheter shaft 2 at the ends of the balloon. The outer balloon 8 may be formed of a non-compliant material. In the illustrated embodiment, the length of the outer balloon is chosen so that it is approximately 4mm longer than the stent. In this and other embodiments, when the stent is crimped around the deflated balloon, the same amount of balloon may extend past the stent on each side i.e. the balloon may, for example, extend past the stent by 2mm on each side.

An inflation lumen 16 is located within the catheter shaft 4. The inflation lumen 16 is in fluid communication with the interior 20 of the inner balloon 6 through an aperture 18 in the catheter shaft 4. A pressurized medium, such as saline, may be introduced into the inflation lumen 16 to inflate the inner balloon. The space between the inner balloon and the outer balloon is not provided with an inflation lumen.

In operation, a guidewire 22 may be routed to the desired inflation location. The balloon catheter, the catheter shaft 4 of which has a guidewire port located adjacent the 00 -6- 0 balloons, with a crimped stent may be then placed over the guidewire 22 and delivered to the desired location. A pressurized medium is introduced into the inflation lumen.

The pressurized medium passes into the interior 20 of the inner balloon 6, and begins to inflate the inner balloon 6. The inner balloon 6 applies pressure to both the stent 14 and the outer balloon 8. Typically, at approximately 3 or 4 atmospheres (depending on the particular stent design chosen), the stent 14 begins to expand. As shown in Fig. 2, Sbecause the inner balloon 6 is shorter than the stent 14, only the middle portion of the Sstent 14 beings to expand. At, for example, approximately five atmospheres, the stent 14 Iis sufficiently expanded so that it is implanted into the vessel wall.

As shown in Fig. 3, upon further application of the pressurized medium to the inflation lumen, the inner balloon 6 ruptures. The burst pressure of the inner balloon may be less than 10 atmospheres, and in some embodiments be approximately atmospheres, for example. Rupture of the inner balloon 6 allows fluid communication between the inflation lumen 16 and the cavity formed between the outer balloon and the inner balloon.

When further pressure is applied to the inflation lumen, the outer balloon expands the entire length of the stent. The operator may then apply as much pressure as desired, up to the burst pressure of the outer balloon to firmly implant the stent.

Typically, the burst pressure of the outer balloon should be greater than that of the inner balloon. Thus, for example, in a particular embodiment the burst pressure of the inner balloon may be selected to be, for example, 5 atmospheres, and the burst pressure of the outer balloon may be selected to be equal to 10 atmospheres, to give an approximately 5 atmosphere difference.

The balloons may then be deflated, and the catheter and guidewire may then be removed.

In the foregoing specification, the invention has been described with reference to specific exemplary embodiments. It will, however, be evident that various modifications and changes may be made thereunto without departing from the broader spirit and scope of the invention as set forth in the appended claims. The specification and drawings are accordingly to be regarded in an illustrative rather than a restrictive sense.

Claims

1. A stent and balloon catheter in combination comprising: a balloon catheter with an inner and an outer balloon, the outer balloon overlaying the inner balloon; and an expandable stent mounted over the inner and outer catheter balloons, C wherein: Sa burst pressure of the inner balloon is less than a burst pressure of the outer balloon, a length of the outer balloon is greater than a length of the stent and a length of the inner balloon is less than the length of the stent; and the burst pressure of said inner balloon being such that, when inflated with a pressurized medium it will expand sufficiently to expand the middle portion of said stent and implant said stent.

2. A combination according to claim 1 wherein the burst pressure of the inner balloon is less than 10 atmospheres.

3. A combination according to claim 1 or claim 2 wherein the burst pressure of the inner balloon is approximately 5 atmospheres.

4. A combination according to claim 1, 2 or 3 wherein the burst pressure of the outer balloon is greater than 10 atmospheres.

A combination according to any one of claims 1 to 4 wherein the outer balloon is formed of a non-compliant material.

6. A combination according to any one of claims 1 to 5 wherein the inner balloon is formed of a non-compliant material. 00-8- O

7. A combination according to any one of claims 1 to 6 wherein the catheter shaft d has a guidewire port located adjacent the balloons.

8. A combination according to any one of claims 1 to 7 wherein the burst pressure of the inner balloon is at least 5 atmospheres less than the burst pressure of the outer t¢3 5 balloon. (N ND

9. A combination according to any one of claims 1 to 8 wherein the burst pressure N of said outer balloon is such that, when inflated with a pressurized medium it will expand sufficiently to expand the entire length of the stent.

A stent and balloon catheter in combination comprising: a balloon catheter with an inner and an outer balloon, the outer balloon overlaying the inner balloon, both said inner balloon and said outer balloon sealed to a catheter shaft at each end; an inflation lumen in said catheter shaft in communication only with an interior of said inner balloon; and an expandable stent mounted over the first and second catheter balloons, wherein: a burst pressure of the inner balloon is less than a burst pressure of the outer balloon, a length of the outer balloon is greater than a length of the stent and a length of the inner balloon is less than the length of the stent; the burst pressure of said inner balloon is such that, when inflated with a pressurized medium from said inflation lumen, it will expand sufficiently to expand the middle portion of said stent and implant said stent, before bursting; and 00 -9- 0 pressurized medium from said inflation lumen can enter the interior of said outer Sballoon to inflate it and further expand the stent over its full length only after said inner Cc balloon bursts.

11. A combination according to claim 10 wherein the burst pressure of the inner balloon is less than 10 atmospheres.

12. A combination according to claim 10 or claim 11 wherein the burst pressure of N, the inner balloon is approximately 5 atmospheres.

13. A combination according to any one of claims 10, 11 or 12 wherein the burst pressure of the outer balloon is greater than 10 atmospheres.

14. A combination according to any one of claims 10 to 13 wherein the outer balloon is formed of a non-compliant material.

A combination according to any one of claims 10 to 14 wherein the inner balloon is formed of a non-compliant material.

16. A combination according to any one of claims 10 to 15 wherein the catheter shaft has a guidewire port located adjacent the balloons.

17. A combination according to any one of claims 10 to 16 wherein the burst pressure of the inner balloon is at least 5 atmospheres less than the burst pressure of the outer balloon.

18. A method of implanting a stent mounted on a balloon catheter with an outer balloon and an inner balloon, the outer balloon overlaying the inner balloon, a burst 00 O pressure of the inner balloon being substantially less than a burst pressure of the outer balloon, said method comprising the steps of: Vj) Cc delivering the balloon catheter and stent to a desired location in a vessel in a body; c 5 inflating the inner balloon to a pressure sufficient to expand a central portion of the stent; IND continuing inflating the inner balloon to a pressure sufficient to burst the inner balloon; inflating the outer balloon to a pressure sufficient to impact the stent; and deflating and removing the balloon catheter.

19. A method according to claim 18, wherein the step of inflating the inner balloon to a pressure sufficient to expand a central portion of the stent implants the central portion of the stent and said step of inflating the outer balloon to a pressure sufficient to implant the stent implants the ends of the stent.

20. A method according to claim 18 or claim 19, wherein the outer balloon has a length longer than the stent and the inner balloon has a length shorter than the stent.

21. A method according to any one of claims 18 to 20, wherein a burst pressure of the outer balloon is over approximately 10 atmospheres and a burst pressure of the inner balloon is less than approximately 5 atmospheres.

22. A method of implanting a stent mounted on a balloon catheter with an outer balloon with a length longer than the stent and an inner balloon with a length shorter than the stent, the outer balloon overlaying the inner balloon, a burst pressure of the 00-11- inner balloon being substantially less than a burst pressure of the outer balloon, said Smethod comprising the steps of: Sdelivering the balloon catheter and stent to a desired location in a vessel in a body; inflating the inner balloon to a pressure sufficient to expand the stent; Ncontinuing inflating the inner balloon to a pressure sufficient to burst the inner IND balloon; Sinflating the outer balloon to a pressure sufficient to implant the stent; and deflating and removing the balloon catheter.

23. A method according to claim 22, wherein the step of inflating the inner balloon to a pressure sufficient to expand the stent expands and implants the central portion of the stent and said step of inflating the outer balloon to a pressure sufficient to implant the stent implants the ends of the stent.

24. A method according to claim 22 or claim 23, wherein a burst pressure of the outer balloon is over approximately 10 atmospheres and a burst pressure of the inner balloon is less than approximately 5 atmospheres.

A stent and balloon catheter in combination substantially as herein described with reference to any one of the embodiments of the invention illustrated in the accompanying drawings and/or examples.

26. A method of implanting a stent mounted on a balloon catheter, said method being substantially as herein described with reference to any one of the embodiments of the invention illustrated in the accompanying drawings and/or examples.