Surgery – Means for introducing or removing material from body for... – Treating material introduced into or removed from body...
Reexamination Certificate
2000-11-14
2003-06-24
Capossela, Ronald (Department: 3763)
Surgery
Means for introducing or removing material from body for...
Treating material introduced into or removed from body...
C604S103050, C623S001150
Reexamination Certificate
active
06582394
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to stent deployment assemblies for use at a bifurcation and, more particularly, a catheter assembly for implanting one or more stents for repairing bifurcations, the aorto-ostium, and bifurcated blood vessels that are diseased, and a method and apparatus for delivery and implantation.
Stents conventionally repair blood vessels that are diseased and are generally hollow and cylindrical in shape and have terminal ends that are generally perpendicular to its longitudinal axis. In use, the conventional stent is positioned at the diseased area of a vessel and, after placement, the stent provides an unobstructed pathway for blood flow.
Repair of vessels that are diseased at a bifurcation is particularly challenging since the stent must overlay the entire diseased area at the bifurcation, yet not itself compromise blood flow. Therefore, the stent must, without compromising blood flow, overlay the entire circumference of the ostium to a diseased portion and extend to a point within and beyond the diseased portion. Where the stent does not overlay the entire circumference of the ostium to the diseased portion, the stent fails to completely repair the bifurcated vessel. Where the stent overlays the entire circumference of the ostium to the diseased portion, yet extends into the junction comprising the bifurcation, the diseased area is repaired, but blood flow may be compromised in other portions of the bifurcation. Unapposed stent elements may promote lumen compromise during neointimalization and healing, producing restenosis and requiring further procedures. Moreover, by extending into the junction comprising the bifurcation, the stent may block access to portions of the bifurcated vessel that require performance of further interventional procedures. Similar problems are encountered when vessels are diseased at their angled origin from the aorta as in the ostium of a right coronary or a vein graft. In this circumstance, a stent overlying the entire circumference of the ostium extends back into the aorta, creating problems, including those for repeat catheter access to the vessel involved in further interventional procedures.
Conventional stents are designed to repair areas of blood vessels that are removed from bifurcations and, since a conventional stent generally terminates at right angles to its longitudinal axis, the use of conventional stents in the region of a vessel bifurcation may result in blocking blood flow of a side branch or fail to repair the bifurcation to the fullest extent necessary. The conventional stent might be placed so that a portion of the stent extends into the pathway of blood flow to a side branch of the bifurcation or extend so far as to completely cover the path of blood flow in a side branch. The conventional stent might alternatively be placed proximal to, but not entirely overlaying the circumference of the ostium to the diseased portion. Such a position of the conventional stent results in a bifurcation that is not completely repaired. The only conceivable situation that the conventional stent, having right-angled terminal ends, could be placed where the entire circumference of the ostium is repaired without compromising blood flow, is where the bifurcation is formed of right angles. In such scenarios, extremely precise positioning of the conventional stent is required. This extremely precise positioning of the conventional stent may result with the right-angled terminal ends of the conventional stent overlying the entire circumference of the ostium to the diseased portion without extending into a side branch, thereby completely repairing the right-angled bifurcation.
To circumvent or overcome the problems and limitations associated with conventional stents in the context of repairing diseased bifurcated vessels, a stent that consistently overlays the entire circumference of the ostium to a diseased portion, yet does not extend into the junction comprising the bifurcation, maybe employed. Such a stent would have the advantage of completely repairing the vessel at the bifurcation without obstructing blood flow in other portions of the bifurcation. In addition, such a stent would allow access to all portions of the bifurcated vessel should further interventional treatment be necessary. In a situation involving disease in the origin of an angulated aorto-ostial vessel, such a stent would have the advantage of completely repairing the vessel origin without protruding into the aorta or complicating repeat access.
In addition to the problems encountered by using the prior art stents to treat bifurcations, the delivery platform for implanting such stents has presented numerous problems. For example, a conventional stent is implanted in the main vessel so that a portion of the stent is across the side branch, so that stenting of the side branch must occur through the main-vessel stent struts. In this method, commonly referred to in the art as the “monoclonal antibody” approach, the main-vessel stent struts must be spread apart to form an opening to the side-branch vessel and then a catheter with a stent is delivered through the opening. The cell to be spread apart must be randomly and blindly selected by recrossing the deployed stent with a wire. The drawback with this approach is there is no way to determine or guarantee that the main-vessel stent struts are properly oriented with respect to the side branch or that the appropriate cell has been selected by the wire for dilatation. The aperture created often does not provide a clear opening and creates a major distortion in the surrounding stent struts. The drawback with this approach is that there is no way to tell if the main-vessel stent struts have been properly oriented and spread apart to provide a clear opening for stenting the side-branch vessel.
Another approach to providing a main-vessel stent that does not block access to the ostium of a side-branch vessel is to cut an aperture in the side-wall of the main-vessel stent. The draw-back to this approach is that forming the aperture in this manner interferes with the structural integrity of the stent in the area of the aperture, resulting in reduced strength and scaffolding. Additionally, where such an aperture is cut into a stent having otherwise closed cells formed from stent struts, the perimeter of the aperture will have open cells and unjoined stent struts presenting a jagged perimeter that may interfere with crossing of the aperture by a guide wire or catheter if subsequent treatment of the side-vessel is required.
In another prior art method for treating bifurcated vessels, commonly referred to as the “Culotte technique,” the side-branch vessel is first stented so that the stent protrudes into the main vessel. A dilatation is then performed in the main vessel to open and stretch the stent struts extending across the lumen from the side-branch vessel. Thereafter, the main-vessel stent is implanted so that its proximal end overlaps with the side-branch vessel. One of the drawbacks of this approach is that the orientation of the stent elements protruding from the side-branch vessel into the main vessel is completely random. Furthermore the deployed stent must be recrossed with a wire blindly and arbitrarily selecting a particular stent cell. When dilating the main vessel stretching the stent struts is therefore random, leaving the possibility of restricted access, incomplete lumen dilatation, and major stent distortion.
In another prior art device and method of implanting stents, a “T” stent procedure includes implanting a stent in the side-branch ostium of the bifurcation followed by stenting the main vessel across the side-branch ostium. In another prior art procedure, known as “kissing” stents, a stent is implanted in the main vessel with a side-branch stent partially extending into the main vessel creating a double-barreled lumen of the two stents in the main vessel distal to the bifurcation. Another prior art approach includes a so-called “trouser legs and seat” approach, which includes implanti
Dennehy Mary
Reiss Paul
Advanced Cardiovascular Systems Inc.
Capossela Ronald
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