1. Technology Field
The present invention generally relates to stents and stent delivery systems, used in intravascular systems. In particular, the present invention relates to a stent that is shaped and configured for placement within a side branch portion of a bifurcated lumen so as to not interfere with an additional stent positioned in the main luminal branch.
2. The Related Technology
Angioplasty and stent implantation procedures are commonly employed to treat lesions or blockages that form within the vascular anatomy of a patient. During an angioplasty, or percutaneous transluminal coronary angioplasty (“PTCA”) procedure, for instance, a guiding catheter is advanced through the vasculature of the patient to a desired point, such as the ostium of a predetermined coronary artery. A guidewire, positioned within a balloon catheter, is extended from a distal end of the guiding catheter into the patient's coronary artery until it penetrates and crosses a lesion to be dilated. The balloon catheter is then advanced through the guiding catheter and over the previously introduced guidewire, until it is properly positioned across the lesion.
Once properly positioned, the balloon is inflated to a predetermined size such that the stenosis of the lesion is compressed against the arterial wall, thereby expanding the passageway of the artery. The balloon is subsequently deflated, blood flow resumes through the dilated artery, and the balloon catheter is removed.
Occasionally, post-procedure restenosis, or reformation of the arterial blockage, occurs after the PTCA procedure has been performed. To reduce the incidence of restenosis and strengthen the dilated area, physicians frequently implant an intravascular prosthesis, generally called a stent, inside the artery at the site of the lesion. During a stent implantation procedure, a stent is delivered in a contracted state on a balloon catheter to the desired location within a coronary artery. Once properly positioned, the stent is expanded to a larger diameter via expansion of the balloon, which causes the stent to expand against the arterial wall at the lesion site. The balloon is then deflated and it and the catheter are withdrawn. The expanded stent remains in place within the artery at the site of the dilated lesion, holding the vessel open and improving the flow of blood therethrough.
Lesions are often located at or near a point of bifurcation in an artery or other body vessel. When treating such bifurcated lesions, it is common to first place a first guidewire in the main branch, then place a second guidewire, extending from the main branch, into the side branch of the vessel bifurcation. This is so because it is generally important to preserve access to, and blood flow within, the side branch and the main branch of the bifurcation.
Specifically, in some instances the above-described dilation via PTCA procedure causes plaque to be shifted from the treated main branch of the vessel bifurcation to the non-treated vessel side branch, thereby occluding the side branch. This effect is known as the “snowplow” effect. Prior placement of the second guidewire in the vessel side branch enables treatment of the side branch should it become occluded due to the snowplow effect.
Treatment of the side branch in this case often includes deployment of a stent therein. The stent is desirably placed in the vessel side branch proximate the bifurcation and deployed so that its proximal end covers as much of the ostium, or vessel opening, as possible.
However, the ostium—which is defined by the intersection of the vessel side branch with the main branch at the point of bifurcation - does not typically define a simple circle, but rather a curvilinear, saddle-shaped profile. This curvilinear ostium profile is typically caused by the oblique angle of intersection of the substantially cylindrical main and side branch vessels. In contrast, known stents currently in use include proximal ends that define a simple flat circular profile.
The disparity between the stent proximal end and ostium profiles typically causes one of two unfortunate results. First, if it is desired for the known stent to cover the entirety of the vessel side branch ostium, the stent is only partially inserted into the lumen of the side branch, resulting in a portion of the proximal end extending from the lumen of the side branch into the lumen of the main branch. Such a placement is highly undesirable as the portion of the side branch stent extending into the main branch can interfere with the proper placement of a stent to be deployed in the main branch proximate or past the bifurcation region.
Alternatively, the stent may be positioned fully into the side branch so that no portion thereof remains in the lumen of the main vessel branch when deployed. However, this placement is also undesirable, for it leaves portions of the side branch ostium uncovered by the deployed stent and therefore susceptible to further degradation or formation of a stenosis.
As seen by the above discussion, therefore, it is sometimes necessary in the treatment of lesions at a bifurcated vessel site to deploy a stent in the side branch so that the stent structure covers the side branch vessel walls beginning from the ostium where the side branch departs from the main vessel branch to the end of the vessel intended for coverage by the stent structure.
Unfortunately, the design of known stents is incapable of acceptably covering the ostium region of bifurcated vessel side branches without causing the above-described complications, again, the failure of the proximal end of the stent to cover the entirety of the ostium region of the side branch, or—in order to cover the entirety of the side branch ostium—the stent proximal end overhangs into the lumen of the vessel main branch.
In light of the above discussion, a need exists for an intraluminal stent suitable for placement at bifurcated vessels. The stent should be advantageously configured so as to cover all portions of the ostium region of the vessel side branch. Furthermore, the stent should be designed so as to prevent stent overhang in the lumen of the vessel main branch so as not to impede the placement of another stent in the main branch.
The present invention has been developed in response to the above and other needs in the art. Briefly summarized, embodiments of the present invention are directed to a contoured intraluminal stent for deployment proximate a bifurcated vessel. The contoured stent is configured to seat within a side branch of the bifurcated vessel so as to acceptably cover a curvilinear ostium defined at the intersection of the side branch with a main branch of the vessel.
A stent deployment system employed with the contoured stent includes a first guidewire positioned in the vessel main branch and a second guidewire that extends through the main branch and into the vessel side branch, wherein the intersection of the branches defines an ostium having a three-dimensionally curvilinear shape. A balloon catheter is tracked along the second guidewire to a position in the side branch proximate the ostium. A contoured stent disposed about the balloon includes a proximal end that defines a curvilinear profile that at least approximately matches the curvilinear shape of the ostium when the stent is deployed in the side branch.
Importantly, the contoured stent is deployed in the lumen of a vessel side branch such that subsequent placement of a second stent in the main branch proximate the vessel bifurcation is not inhibited by the contoured stent. This is so because the proximal end of the contoured stent is shaped so as to match the shape of the ostium of the side branch, thereby preventing overhang of the contoured stent proximal end into the lumen of the main branch. In other embodiments, the proximal and/or distal end of the stent can be shaped so as to match ostiums or vessel portions having other shape configurations.
These and other features of the present invention will become more fully apparent from the following description and appended claims, or may be learned by the practice of the invention as set forth hereinafter.
To further clarify the above and other advantages and features of the present invention, a more particular description of the invention will be rendered by reference to specific embodiments thereof that are illustrated in the appended drawings. It is appreciated that these drawings depict only typical embodiments of the invention and are therefore not to be considered limiting of its scope. The invention will be described and explained with additional specificity and detail through the use of the accompanying drawings in which:
Reference will now be made to figures wherein like structures will be provided with like reference designations. It is understood that the drawings are diagrammatic and schematic representations of exemplary embodiments of the invention, and are not limiting of the present invention nor are they necessarily drawn to scale.
Reference is first made to
Because of the oblique angle of intersection of the side branch 14 with the main branch 12, together with the generally cylindrical cross sectional shapes of the branches, the ostium 16 defines a three-dimensional curvilinear profile, approximating a saddle shape, as indicated by the line 17. Again, because of the nature of the intersection of the vessel side branch 14 with the main branch 12, the non-uniform curvilinear profile of the ostium 16 includes a carina, or inset, 18. The inset 18 presents a particular challenge for standard, known stents because of their inability to acceptably cover the inset and other regions of the ostium when deployed without causing other challenges.
In contrast, the stent disclosed in embodiments of the present invention is configured to deploy so as to acceptably cover all portions of the ostium 16. Particularly,
Note that the particular contour of the proximal end of the stent can be altered in shape and configuration from what is described herein so as to acceptably match ostiums of other vessels, both bifurcated and non-bifurcated, having other curvilinear shapes. For example, the profile of the stent proximal end in one embodiment can include two or more inset portions to acceptably match a similarly contoured vessel ostium when the stent is deployed in the lumen of the vessel. Or, the proximal end can define an elliptical shape, or other curvilinear or non-curvilinear shape. As such, the presently described embodiments should not be construed to limit the present invention in any manner.
Together with
As shown in
Reference is now made to
The contoured stent 20 is included about the balloon 46 in its collapsed state, prior to deployment at the lesion site. The stent proximal end 26 is disposed proximally in the lumen of the vessel main branch 12. As shown, the first guidewire 40 passes through the stent body 22 at a location 48 that is proximate a distal edge, or tip, of the inset portion 28 of the stent. Positioned in this manner, the first guidewire 40 is capable of orienting the contoured stent 20 into a desired orientation within the vessel lumen as the balloon catheter 44 travels over the second guidewire 42 via the vessel lumen(s) to the bifurcation location where the stent will be ultimately positioned in the vessel side branch 14.
Specifically, orientation of the contoured stent 20 by the first guidewire 40 is accomplished in one embodiment by maintaining a desired amount of tension between the first guidewire and the contoured stent 20 disposed about the balloon 46 of the balloon catheter 44 as the balloon catheter is tracked along the second guidewire 42. This tension, together with proper positioning of the first guidewire 40 in the vessel lumen, exerts a force on the contoured stent 20 such that the balloon catheter and stent are rotated as needed about a longitudinal axis of the balloon catheter so as to maintain the inset portion and rest of the contoured stent 20 in a desired orientation. The first guidewire 40 can exert a continual force on the contoured stent 20 so as to maintain the desired stent orientation during intraluminal advancement of the balloon catheter 44. Maintaining the desired contoured stent orientation is beneficial for properly placing the stent at the vessel bifurcation, as will be seen in connection with the discussion of
Reference is now made to
In
In detail, it is desired that the contoured stent 20 be positioned such that its inset portion 28 is aligned with the inset 18 of the side branch ostium 16. In this way, the proximal end 26 of the contoured stent 20 is oriented as desired in order to cover the entirety of the ostium region of the vessel side branch 14 while not extending into the lumen of the main branch 12. Again, the first guidewire 40, received through the portion 48 of the stent body 22, is used to ensure such desired positioning of the stent 20 while still crimped on the balloon catheter 44.
In
Note that configuration of the contoured stent or associated deployment system can be modified from what is described herein, while still residing within the claims of the present invention. For instance, the contoured stent can be configured such that the first guidewire passes through another portion of the stent other than at the distal apex of the inset portion 28. These and other modifications are therefore contemplated as part of the present invention.
Details regarding yet another system for deploying the contoured stent of the present invention can be found in the U.S patent application entitled “SYSTEM AND METHOD FOR DELIVERING A STENT TO A BIFURCATED VESSEL,” filed Mar. 8, 2007, (attorney docket no. 17066.33.3), which is incorporated herein by reference in its entirety.
The present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrative, not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. All changes that come within the meaning and range of equivalency of the claims are to be embraced within their scope.
This application claims the benefit of the U.S. Provisional Patent Application No. 60/780,752, filed Mar. 9, 2006, and entitled “Contoured Stent and Delivery System with Novel Tip Design,” which is incorporated herein by reference in its entirety.
Number | Date | Country | |
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60780752 | Mar 2006 | US |