1. Field of the Invention
This invention relates to medical devices, and more particularly, to endoluminal devices and methods for making and using such endoluminal devices.
2. Description of Related Art
The functional vessels of human and animal bodies, such as blood vessels and ducts, occasionally weaken or even rupture. For example, an aortic wall can weaken, resulting in an aneurysm. Upon further exposure to hemodynamic forces, such an aneurysm can rupture, resulting in internal bleeding, and often death.
Various interventions have been provided for weakened, aneurysmal, dissected or ruptured vessels, including surgical interventions and endovascular interventions. Endovascular interventions generally include inserting an endoluminal device or prosthesis such as a stent or stent graft into the damaged or diseased body lumen to provide support for the lumen, and to exclude damaged portions thereof.
The endovascular prosthesis is delivered in a radially compressed configuration using a catheter delivery system. The catheter is introduced into the lumen system remotely of the repair site and the prosthesis is delivered to the repair site intraluminally. The prosthesis is then expanded to engage the luminal wall. The prosthesis may provide some or all of the functionality of the original, healthy vessel and may further preserve any remaining vascular integrity.
An example of a prosthesis that may be used for treating damaged or diseased body lumens is disclosed in PCT Application WO 98/53761, which is herein incorporated by reference. The prosthesis may include a bifurcated stent graft. The stent graft includes a biocompatible graft material and a plurality of longitudinally disposed stents. The stent graft is designed to span and exclude an aortic aneurysm extending between the iliac and renal arteries. Other prostheses that may be used include non-bifurcated stent grafts for spanning and excluding aortic aneurysms within the abdominal aorta or the thoracic aorta.
Often times, a body lumen may be damaged in an area that includes a branch vessel. For example, there are at least three branch vessels extending from the abdominal aorta, each leading to various body organs. These branch vessels include the celiac, mesenteric, and renal arteries. When an aneurysm includes or is adjacent to one or more of these branch vessels, the prosthesis system must be able to exclude the aneurysm while maintaining fluid flow through the branch body lumen.
Various stent grafts have been provided for repairing main body lumens and spanning branch vessels without occluding fluid flow thereto. For example, a main body stent graft may be provided that has one or more fenestrations or apertures in the side wall of the stent graft. The stent graft can be deployed so that the fenestration is aligned with a branch vessel.
In many cases, particularly where the damaged portion is positioned at the junction between the main body lumen and the branch body lumen, or where the ostium of the branch vessel is damaged, a main stent graft is insufficient to adequately repair the luminal system. In these situations, it may be preferable to provide a branch lumen prosthesis for positioning within the branch vessel. The branch lumen prosthesis may be used independently, or in conjunction with a main body prosthesis.
U.S. Published Patent Application Nos. 2005/0222668, 2005/0171598, and 2005/0149166 disclose various systems for repairing branched body lumen systems. Various aspects of each of these disclosures may be used in conjunction with the present invention. U.S. Published Patent Application Nos. 2005/0222668, 2005/0171598, and 2005/0149166 are herein incorporated by reference.
A branch vessel prosthesis should be capable of complying with a variety of challenging and often competing demands. For example, the branch vessel prosthesis should preferably be highly flexible and capable of tracking through and conforming with a highly tortuous luminal environment. If the prosthesis includes a balloon-expandable stent, the stent should be sufficiently resilient so as not to hinder balloon expansion and/or molding.
On the other hand, once the prosthesis is implanted in the body lumen, it must be sufficiently strong and robust to survive a highly dynamic and pulsatile luminal environment that can promote prosthesis damage. This is of particular concern where the branch vessel prosthesis is deployed within a fenestration of a main body prosthesis. During the cardiac cycle, the main body prosthesis will pulse and move with the main body vessel, placing stress on the branch vessel prosthesis at the fenestration. When the main body prosthesis moves, it can exert significant concentrated and localized stresses on the branch vessel prosthesis 11 through the fenestration. Over time, this cyclic wear can cause the branch vessel prosthesis to weaken and eventually to crush under the force of the main body prosthesis, requiring further medical intervention.