Prosthesis (i.e. – artificial body members) – parts thereof – or ai – Arterial prosthesis – Stent structure
Reexamination Certificate
2001-07-02
2002-09-17
Thaler, Michael H. (Department: 3731)
Prosthesis (i.e., artificial body members), parts thereof, or ai
Arterial prosthesis
Stent structure
C623S001130, C623S001360
Reexamination Certificate
active
06451051
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of Invention
The present invention relates to a vascular implant that is implanted into an artery for repair or bypass of arterial injury. The vascular implant includes a stent-graft that is delivered intraluminally into an artery for repair of a vascular lesion and more specifically for repair of abdominal aortic aneurysm. The vascular implant further includes an attachment means that provides attachment of a stent-graft to a vessel wall.
2. Description of Prior Art
An abdominal aortic aneurysm is an outpouching of the wall of the aorta that can continue to expand over time possibly leading to rupture and mortality. The outpouched wall is generally filled with thrombus except for a generally tortuous pathway for blood flow through an opening in the thrombus. This thrombus can become organized over time as fibroblasts and other cell types infiltrate and form a more organized matrix material containing collagen and other tissue. Typically such aneurysms occur below or caudal to the renal arteries or veins and can extend distally into the right or left common iliac arteries or further distally into the right or left femoral arteries. The right renal vein which crosses over the ventral surface of the aorta can provide some support to the ventral surface of the aorta an help resist aortic distention. Aortic distention can occur very abruptly just distal to the renal vessels reaching a diameter of six centimeters or greater and causing the onset of accompanying symptoms and requiring repair. Generally the blood flow pathway through the thrombus does not follow these abrupt changes found in the vessel wall but rather continues on in a more direct albeit tortuous path through the thrombus found in the aneurysmal aorta. The abdominal aortic aneurysm can sometimes have a proximal neck or region where the aortic diameter appears to be of normal diameter. This proximal neck region is sometimes found just caudal to the renal vessels. The abdominal aortic aneurysm can sometimes also have a distal neck region located just proximal to the aorto-iliac bifurcation. In this minority of patients the abdominal aortic aneurysm does not extend to the iliac arteries or farther distally. Aortic distention in the majority of patients can extend into one or both of the iliac or femoral arteries; repair of this abdominal aortic aneurysm can involve treatment of the iliac and femoral arteries as well. The common iliac artery divides to form the external and internal iliac arteries. The internal iliac artery (also called the hypogastric artery) is important in providing a supply or blood to the pelvic region, genital organs, and other areas and is most often not aneurysmal. The external iliac artery is commonly involved in the aneurysm and extends distally along an oftentimes very tortuous path to form the common femoral artery.
Surgical repair of an abdominal aortic aneurysm is an extensive procedure associated with a high incidence of morbidity and mortality and requiring many days of hospital stay. Older patients are often not capable of withstanding the trauma associated with this surgery. Repair of abdominal aortic aneurysm intraluminally through access from the common femoral artery can provide the patient with an alternate method of treatment for abdominal aortic aneurysm without the accompanying surgical trauma and long hospital stay. Placement of an intraluminal stent-graft can be performed by an interventionalist using a minimal surgical cutdown to an ipsilateral common femoral artery for access of the device to the arterial system of the body. Generally an additional access site is placed percutaneously in the contralateral common femoral artery. It is often preferred to place at least one more access site cranial to the abdominal aortic aneurysm generally through an axillary artery or other artery of the arm. Spiral computed tomography, duel-plane angiography, intravascular ultrasound, magnetic resonance imaging, and fluoroscopy provide some of the diagnostic techniques used to determine the position, diameter, and length of the aneurysm such that an appropriate intraluminal prosthesis can be selected for intraluminal implantation. Placement of the intraluminal stent-graft requires that a leak tight seal be made between the stent-graft and the aorta and between the stent-graft and each of the iliac or femoral arteries if they are involved in the aneurysm. Failure to provide such a leak tight seal will allow blood flow at arterial pressure to access the space between the stent-graft and the outpouched aorta. Continued exposure to arterial blood pressure can result in further expansion of the aneurysmal sac and could lead to sac rupture. Several intraluminal stent-grafts have been described for use in treatment of abdominal aortic aneurysms.
Barone describes in U.S. Pat. No. 5,578,072 an apparatus for repairing an abdominal aortic aneurysm. He describes a one-piece bifurcated aortic graft having a balloon expandable stent at one end to secure main trunk of the stent-graft to the aorta caudal to the renal arteries. The one-piece aortic graft has additional expandable stents positioned at the end of each leg of the bifurcated graft to secure the stent-graft to the iliac arteries. This design requires that the length of the main trunk and length of each limb be established prior to implantation using the diagnostic techniques described earlier. Due to the tortuous nature of the blood flow pathway, it is impossible to properly size the length of the graft using these diagnostic techniques prior to implatation. If the stent-graft is sized too short, then a portion of the aneurysm may be left unprotected. If the stent-graft is sized too long for example, then the blood flow to one or both of the internal iliac arteries may be compromised. The method of securing the main trunk of the stent-graft to the aorta caudal to the renal arteries described by Barone is also inadequate in many situations. A balloon expandable stent placed caudal to the renal vessels will very often be located within thrombus and will not have the strength or stability of the aortic vessel wall to support the stent or the stent-graft from migration caudally. Barone teaches that a securing means that is expanded outwardly over an axial length will hold the cranial end of the main trunk in position near the renal vessels. Barone also does not describe any means to prevent the stent-graft from being kinked or crushed as it travels through the thrombus laden blood flow pathway within the aortic aneurysm. Forces imposed upon the stent-graft due to the surrounding thrombus or thrombus organization could easily cause the stent-graft of Barone to become kinked or stenotic thereby impairing its performance. Barone discusses the need to place a stent proximal to the renal arteries for the case that the abdominal aortic aneurysm extends through the aortic region containing the renal arteries. He does not provide a suitable stent-graft for treating infrarenal aortic aneurysm with abrupt wall distension just distal to the renal vessels.
Parodi describes in U.S. Pat. No. 5,591,229 stent-graft devices that are similar to those described by Barone in the above patent. Additionally, Parodi describes a stent-graft for treatment of an abdominal aortic aneurysm that does not extend into the iliac region. This straight tubular stent-graft has a balloon expandable stent positioned at its cranial end for placement into the proximal neck of the aorta distal to the renal vessels. A balloon expandable malleable wire is placed at the distal end of the stent-graft to provide contact of the stent-graft with the aortic wall in the distal neck of the aorta. This stent-graft has a similar problem associated with estimating the graft length due to the tortuosity associated with the blood flow pathway through the thrombus laden aortic aneurysm. The other problem sited with the device described by Barone are similarly shared by the Parodi device.
Chuter describes in U.S. Pat. No. 5,693,084 a one-piece bifurcated stent-graft for
Drasler William J.
Thielen Joseph M.
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