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Extendible stent apparatus and method for deploying the sameRelated Patent Categories: Prosthesis (i.e., Artificial Body Members), Parts Thereof, Or Aids And Accessories Therefor, Arterial Prosthesis (i.e., Blood Vessel), BifurcatedExtendible stent apparatus and method for deploying the same description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20060085061, Extendible stent apparatus and method for deploying the same. Brief Patent Description - Full Patent Description - Patent Application Claims
BACKGROUND [0001] A type of endoprosthesis device, commonly referred to as a stent, is placed or implanted within a vein, artery or other tubular body organ for treating occlusions, stenoses, or aneurysms of the vessel. These stent devices are implanted within tubular vessels to reinforce collapsing, partially occluded, weakened, or abnormally dilated segments of the vessel wall. Stents have been used to treat dissections in blood vessel walls caused by balloon angioplasty of the coronary arteries as well as peripheral arteries and to improve angioplasty results by preventing elastic recoil and remodeling of the vessel wall. [0002] Stents also have been successfully implanted in the urinary tract, the bile duct, the esophagus and the tracheo-bronchial tree to reinforce those body organs. Two randomized multicenter trials have recently shown a lower restenosis rate in stent treated coronary arteries compared with balloon angioplasty alone (Serruys P W et. al. New England Journal of Medicine 331: 489-495, 1994, Fischman D L et. al. New England Journal of Medicine 331: 496-501, 1994). [0003] One of the drawbacks of conventional stents is that they are produced in a straight tubular configuration. The use of such stents to treat disease at or near a branch or bifurcation of a vessel runs the risk of compromising the degree of patency of the primary vessel and/or its branches or bifurcation and also limits the ability to insert a second stent into the side branch if the angioplasty result is suboptimal. This may occur as a result of several mechanisms such as displacing diseased tissue or plaque shifting, vessel spasm, dissection with or without intimal flaps, thrombosis, and embolism. [0004] The risk of branch compromise is increased in two anatomical situations. First the side branch can be compromised when there is a stenosis in the origin of the side branch. Second, when there is an eccentric lesion at the bifurcation site, asymmetric expansion can cause either plaque shifting or dissection at the side branch origin. There are reports of attempting to solve this problem by inserting a balloon into the side branch through the stent struts; however, this technique carries the risk of balloon entrapment and other major complications (Nakamura, S. et al., Catheterization and Cardiovascular Diagnosis 34: 353-361 (1995)). Moreover, adequate dilatation of the side branch is limited by elastic recoil of the origin of the side branch. In addition, the stent may pose a limitation to blood flow and may limit access to the side branch. The term "stent jail" is often used to describe this concept. In this regard, the tubular slotted hinged design of the Palmaz-Schatz intracoronary stent, in particular, is felt to be unfavorable for lesions with a large side branch and it is believed to pose a higher risk of side branch vessel entrapment where the stent prevents or limits access to the side branch. Id. [0005] One common procedure for implanting the endoprosthesis or stent is to first open the region of the vessel with a balloon catheter and then place the stent in a position that bridges the treated portion of the vessel in order to prevent elastic recoil and restenosis of that segment. The angioplasty of the bifurcation lesion has traditionally been performed using the kissing balloon technique where two guidewires and two balloons are inserted, one into the main branch and the other into the side branch. Stent placement in this situation will require the removal of the guidewire from the side branch and reinsertion of the guidewire via the stent struts and insertion of a balloon through the struts of the stent. The removal of the guidewire poses the risk of occlusion of the side branch during the deployment of the stent in the main branch. [0006] Prior art patents refer to the construction and design of both the stent as well as the apparatus for positioning the stent within the vessel. One representative patent to Chaudhury, U.S. Pat. No. 4,140,126, discloses a technique for positioning an elongated cylindrical stent at a region of an aneurysm to avoid catastrophic failure of the blood vessel wall. The '126 patent discloses a cylinder that expands to its implanted configuration after insertion with the aid of a catheter. Dotter, U.S. Pat. No. 4,503,569, discloses a spring stent which expands to an implanted configuration with a change in temperature. The spring stent is implanted in a coiled orientation and is then heated to cause the spring to expand. Palmaz, U.S. Pat. No. 4,733,665, discloses a number of stent configurations for implantation with the aid of a catheter. The catheter includes a mechanism for mounting and retaining the vascular prosthesis or stent, preferably on an inflatable portion of the catheter. The stents are implanted while imaged on a monitor. Once the stent is properly positioned, the catheter is expanded and the stent separated from the catheter body. The catheter can then be withdrawn from the subject, leaving the stent in place within the blood vessel. Palmaz, U.S. Pat. No. 4,739,762, discloses an expandable intraluminal graft. Schjeldahl et. al., U.S. Pat. No. 4,413,989, discloses a variety of balloon catheter constructions. Maginot, U.S. Pat. No. 5,456,712 and Maginot, U.S. Pat. No. 5,304,220 disclose graft and stent assembly and method of implantation where a stent is used to reinforce a graft surgically inserted into a blood vessel in order to bypass an occlusion. However, none of these patents relate to the treatment of bifurcation lesions, or disclose a bifurcating stent apparatus and method for deploying the same. [0007] Taheri, U.S. Pat. No. 4,872,874, Piplani et. al., U.S. Pat. No. 5,489,295, and Marin et al., U.S. Pat. No. 5,507,769, disclose bifurcating graft material which may be implanted with stents. However, there is no mention of bifurcation of the stent, and the stent is used only to anchor the graft into the vessel wall. It does not reinforce the vessel wall, nor does it prevent restenosis after angioplasty. [0008] MacGregor, U.S. Pat. No. 4,994,071, discloses a hinged bifurcating stent. In the 071' patent, in contrast to the present invention, there is a main stent with two additional stents attached at one end, creating a single unit with a bifurcation. The two additional stents are permanently attached and cannot be removed from the main stent. Thus, this invention may not be used in non-bifurcation vessels. In addition, studies with hinge-containing stents have shown that there is a high incidence of restenosis (tissue growth) at the hinge point that may cause narrowing or total occlusion of the vessel and thus compromise blood flow. Furthermore, this design has a relatively large size which makes insertion into the vessel difficult. Also, by having the two additional stents connected to the main stent, tracking into a wide-angle side branch may be difficult and may carry the risk of dissection of the vessel wall. Furthermore, once the device of the '071 patent is implanted, it is impossible to exchange the side branch stent should the need for a different stent size arise. [0009] In general, when treating a bifurcation lesion using commercially available stents, great care should be taken to cover the origin of the branch because if left uncovered, this area is prone to restenosis. In order to cover the branch origin, conventional stents must either protrude into the lumen of the main artery or vessel from the branch (which may causes thrombosis [clotting of blood], again compromising blood flow), or they must be placed entirely within the branch, and will generally not cover the origin of the bifurcation. Another frequent complication experienced with the stenting of bifurcations include narrowing or occlusion of the origin of a side branch spanned by a stent placed in the main branch. Lastly, placement of a stent into a main vessel where the stent partially or completely extends across the opening of a branch may make future access into such branch vessels difficult if not impossible. [0010] In addition, conventional stent technology is inadequate as a means of treating ostial lesions. Ostial lesions are lesions at the origin of a vessel. For example, ostial lesions may form in renal arteries, which are side branches extending from the aorta. Ostial lesions are prone to restenosis due to elastic recoil of the main vessel, such as the aorta. Therefore, the stent cover must include the thickness of the wall of the main vessel. This is extremely difficult to accomplish without protrusion of the stent into the main vessel. [0011] Lastly, conventional stents are difficult to visualize during and after deployment. While some prior art balloon catheters are "marked" at the proximal and distal ends of the balloon with imageable patches, no FDA-approved stents are currently available which are themselves imageable through currently known imaging procedures used when inserting the stents into a vessel. [0012] Accordingly, there is a need for an improved stent apparatus and method for deploying the same which 1) may be used to effectively treat bifurcation lesions which reduces the risk of restenosis or occlusion of the side branch and which completely covers bifurcation lesions with the stent apparatus, 2) may be used to treat lesions in one branch of a bifurcation while preserving access to the other branch for future treatment, 3) may be used to treat ostial lesions, 4) allows for differential sizing of the stents in a bifurcated stent apparatus even after the main stent is implanted, and which 5) may be readily visualized by current or future visualization techniques. SUMMARY OF THE INVENTION [0013] The present invention concerns a novel extendable stent apparatuses and method for deploying the same. More particularly, the invention concerns a stent apparatus comprising an extendable stent which is suitable for treating bifurcation lesions, and which may also be used to treat lesions at the origin of a blood vessel or other organ. As used herein, the term "vessel" means any tubular tissue, and is not limited to vessels of the vascular system. Devices constructed in accordance with the invention include, singularly or in combination, a flared stent comprising a compressible flared portion at its proximal end, which flared portion may comprise hooks, compressible mesh or any other means of creating such a flared portion at the proximal end of the stent, and a main stent comprising at least one substantially circular opening located between its proximal and distal ends. For ease of visualization, both the flared stent and the main stent may be comprised of materials which are imageable, or the stents of the invention may be "marked" at the ends with an imageable substance and the main stent may also be marked at any opening. At least one flared stent may be extended through at least one opening of the main stent into at least one branch vessel for treating bifurcated or branched lesions, or the stents of the invention may be inserted individually for the treatment of ostial lesions, or lesions near bifurcations requiring a stent in either the main or the branch vessel with unobstructed access to the unstented vessel in the bifurcation. The methods of the invention comprises a two-step process used to deploy both the main and the flared stent in a bifurcated vessel, or to deploy the main stent only within a bifurcated vessel. [0014] The stent apparatus of the invention may be constructed from any non-immunoreactive material that allows the apparatus to be expanded from an initial shape to a shape which conforms to the shape of the vessel or vessels into which the apparatus is inserted, including but not limited to any of the materials disclosed in the prior art stents, which are incorporated herein by reference. It is hypothesized that the stent apparatuses of the invention may further be constructed of a substance which is observable by imaging methods including but not limited to magnetic resonance, ultrasound, radio-opaque or contrast-dye, or may be marked at certain points including but not limited to the ends and around any opening or flared portion in a stent of the invention, with a material which is discernable by imaging methods as described above. [0015] A stent constructed in accordance with the invention is suitable for implantation into any vessel in the body, including but not limited to vessels in the cardiac system, the peripheral vascular system, the carotid and intracranial vessels, the venous system, the renal system, the biliary system, the gastrointestinal system, the tracheobronchial system, the biliary system and the genitourinary system. [0016] The stents of the invention are deployed utilizing a set of guidewires and catheters, which are then withdrawn from the subject following deployment of the stents. The stents of the invention may be self-expanding to conform to the shape of the subject vessel, or they may be expanded utilizing balloon catheters, or by any method currently known or developed in the future which is effective for expanding the stents of the invention. The flared stent of the invention is constructed such that the flared portion is confined along the wall of the flared stent by a sheath running parallel to the longitudinal axis of the flared stent until deployment, during which the sheath is removed and the flared portion is expanded into a configuration extending radially, at least in part, from the longitudinal axis of the flared stent. [0017] Thus, it is an object of the present invention to provide a double-stent apparatus which makes it possible to completely cover the origin of a bifurcation lesion with a stent apparatus. [0018] Another object of the invention is to provide a single-stent apparatus and method for deploying the same which may be used to treat only one branch of a bifurcation lesion but which will facilitate future treatment of the corresponding branch. [0019] Yet another object of the invention is to provide a single-stent apparatus which is effective in treating ostial lesions. [0020] A further object of the invention is to provide a method for insertion of the extendable double-stent apparatus into both the main and branch vessels of a bifurcation lesion. [0021] Additionally, it is an object of the invention to provide a stent apparatus which is imageable during and after insertion. [0022] These objects and other object advantages and features of the invention will become better understood from the detailed description of the invention and the accompanying drawings. Continue reading about Extendible stent apparatus and method for deploying the same... Full patent description for Extendible stent apparatus and method for deploying the same Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Extendible stent apparatus and method for deploying the same patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. 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