Prosthesis (i.e. – artificial body members) – parts thereof – or ai – Arterial prosthesis – Having variable diameter
Reexamination Certificate
1998-08-12
2001-03-27
Willse, David H. (Department: 3738)
Prosthesis (i.e., artificial body members), parts thereof, or ai
Arterial prosthesis
Having variable diameter
C606S153000, C623S001360, C623S001140
Reexamination Certificate
active
06206913
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention generally relates to devices and methods for performing a vascular anastomosis, and more particularly to stents for securing a graft vessel to a target vessel.
Vascular anastomoses, in which two vessels within a patient are surgically joined together to form a continuous channel, are required for a variety of conditions including coronary artery disease, diseases of the great and peripheral vessels, organ transplantation, and trauma. For example, in coronary artery disease (CAD), an occlusion or stenosis in a coronary artery interferes with blood flow to the heart muscle. In order to restore adequate blood flow to the heart, a graft vessel in the form of a prosthesis or harvested artery or vein is used to reroute blood flow around the occlusion. The treatment, known as coronary artery bypass grafting (CABG), can be highly traumatic to the patient's system.
In conventional CABG a large incision is made in the chest and the sternum is sawed in half to allow access to the heart. In addition, cardiopulmonary bypass, in which the patient's blood is circulated outside of the body through a heart-lung machine, is used so that the heart can be stopped and the anastomosis performed. In order to minimize the trauma to the patient's system induced by conventional CABG, less invasive techniques have been developed in which the surgery is performed through small incisions in the patient's chest with the aid of visualizing scopes. Less invasive CABG can be performed on a beating or a non-beating heart and thus may avoid the need for cardiopulmonary bypass.
In both conventional and less invasive CABG, the surgeon has to suture the graft vessel in place between the coronary artery and a blood supplying vein or artery. The suturing procedure is a time consuming, difficult process requiring a high level of surgical skill. In order to perform the suturing procedure, the surgeon must have relatively unobstructed access to the anastomotic site within the patient. As a result, in less invasive approaches which provide only limited access to the patient's vessels, some of the major coronary vessels cannot be reached adequately, which can result in incomplete revascularization and a resulting negative effect on patient survival. Moreover, certain target vessels, such as heavily calcified coronary vessels, vessels having a very small diameter of less than about 1 mm, and previously bypassed vessels, may make the suturing process difficult or impossible, so that a sutured anastomosis is not possible.
Additionally, a common problem with CABG has been the formation of thrombi and atherosclerotic lesions at and around the grafted artery, which can result in the reoccurrence of ischemia. Moreover, second operations necessitated by the reoccurrence of arterial occlusions are technically more difficult and risky due to the presence of the initial bypass. For example, surgeons have found it difficult to saw the sternum in half during the next operation without damaging the graft vessels from the first bypass which are positioned behind the sternum.
Therefore, it would be a significant advance to provide a sutureless vascular anastomosis in which the graft vessels can be positioned on a variety of locations on target vessels having a variety of different diameters, which is easily performed, and which minimizes thrombosis associated with the anastomosis. The present invention satisfies these and other needs.
SUMMARY OF THE INVENTION
The invention is directed to anastomotic stents for connecting a graft vessel to a target vessel, and methods of use thereof. The anastomotic stents of the invention are suitable for use in a variety of anastomosis procedures, including coronary artery bypass grafting. The term “target vessel” refers to vessels within the patient which are connected to either or both of the upstream and the downstream end of the graft vessel. One embodiment of the invention comprises a large vessel anastomotic stent for use with large diameter target vessels such as the aorta or its major side branches. Another embodiment of the invention comprises a small vessel anastomotic stent for use on a target vessel which has a small diameter such as a coronary artery. Another aspect of the invention involves applicators for use with the stents of the invention. The terms “distal” and “proximal” as used herein refer to positions on the stents or applicators relative to the physician. Thus, the distal end of the stent is further from the physician than is the stent proximal end. The proximal end of an implanted stent is further from the center of the target vessel lumen than is the stent distal end.
The large vessel anastomotic stents of the invention generally comprise a substantially cylindrical body having a longitudinal axis, an open proximal end, an open distal end, a lumen therein, and at least one deformable section which radially expands to form a flange. The stent, with one end of a graft vessel attached thereto, is inserted into an incision in a wall of the target vessel with the deformable section in a first configuration, and the deformable section is radially expanded to a second configuration to deploy the flange. The flange applies an axial force, substantially aligned with the stent longitudinal axis, against the wall of the target vessel. Additionally, the flange is configured to apply a radial force, substantially transverse to the stent longitudinal axis, against the wall of the target vessel, to secure the stent to the target vessel.
In one embodiment of the large vessel stent, the stent has a single deformable section forming a flange, preferably on a distal section of the stent. However, a plurality of deformable sections may be provided on the stent. For example, in an alternative embodiment, the stent has a second deformable section on a proximal section of the stent. With the proximal and distal end flanges deployed, the stent is prevented from shifting proximally out of the target vessel or distally further into the interior of the target vessel.
The large vessel stents of the invention are configured to connect to target vessels of various sizes having a wall thickness of at least about 0.5 mm, and typically about 0.5 mm to about 5 mm. In one embodiment of the invention, the large vessel anastomotic stent is configured to longitudinally collapse as the deformable section is radially expanded. The surgeon can control the longitudinal collapse to thereby position the distal end flange at a desired location at least partially within the incision in the target vessel wall. Moreover, in the embodiment having a proximal end flange, the surgeon can control the position of the proximal end flange by longitudinally collapsing the stent to a greater or lesser degree, to thereby position the proximal end flange at a desired location in contact with the target vessel. Thus, regardless of the thickness of the target vessel wall, the stent can be longitudinally collapsed to position the flanges against the target vessel wall and effectively connect the stent thereto. This feature is significant because the stent must be connected to target vessels which have a wide range of wall thickness. For example, the aortic wall thickness is typically about 1.4 mm to about 4.0 mm. Therefore, regardless of the thickness of the target vessel wall, the degree of deployment of the proximal end flange, and thus the longitudinal collapse of the stent, can be controlled by the physician to thereby effectively connect the stent to the target vessel. For example, the surgeon may choose between partially deploying the proximal end flange so that it is positioned against an outer surface of the target vessel wall, or fully deploying the flange to. position it in contact with the media of the target vessel wall within the incision in the target vessel wall.
In a presently preferred embodiment, the graft vessel is attached to the stent before insertion into the patient by placing the graft vessel within the lumen of the stent, and everting the end of
Hausen Bernard A.
Yencho Stephen A.
Burns Doane Swecker & Mathis L.L.P.
Jackson Suzette J.
Vascular Innovations, Inc.
Willse David H.
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