The present invention is generally directed to an expandable stent-graft made from a stent covered with expanded polytetrafluoroethylene.
The use of covered expandable stent-grafts for bodily lumen repair is known in the art. Covered expandable stent-grafts may be implanted in a radially compressed state, generally using a catheter, into blood vessels, urinary tracts, biliary tracts, esophageal, femoralpopliteac, venous, iliac, arterial-venus, venus cava, tracheo bronchial, abdominal aorta, thoracic aorta, coronary arteries, carotid arteries, colonic, fallopian, eustachian, ureter, urethra, prostrate or virtually any duct, gorge, or body chamber in a body.
The expandable stent-graft is generally positioned and released from a delivery catheter at a damaged area as desired. Expandable stent-grafts provide outward pressure and support for the body lumen walls, thus creating improved passageways. The addition of a covering on an expandable stent acts to reduce cell growth or occlusions in the interior of the lumen.
Coverings and covered expandable stents that are known in the art are disclosed in the following documents: U.S. Pat. No. 3,953,566 to Gore; U.S. Pat. No. 4,655,771 to Wallsten; U.S. Pat. No. 5,061,275 to Wallsten et al; U.S. Pat. No. 5,112,900 to Buddenhagen et al; U.S. Pat. No. 5,123,917 to Lee; U.S. Pat. No. 5,282,823 to Schwartz et al; U.S. Pat. No. 5,282,824 to Gianturco, U.S. Pat. No. 4,850,999 to Planck, European Patent Application No. 0 621 015 A1 to Lukic, European Patent Application No. 0 551 179 A1 to Palmaz, DE 3918736-A1 to Vallbracht, Patent Cooperation Treaty Application WO 95/05131 to Gore, Patent Cooperation Treaty Application WO 95/05132 to Gore, Patent Cooperation Treaty Application WO 95/05555 to Gore; Patent Cooperation Treaty Application WO 87/04935 to Fischell. (All documents cited herein, including the foregoing, are incorporated herein in their entireties for all purposes.)
It is an object of the present invention to provide an expandable stent-graft which is covered, at least in part, with expanded polytetrafluoroethylene (ePTFE).
Other objects of the invention will become apparent to those skilled in the art through familiarization with the specification and claims herein.
The expandable stent-graft of the present invention is designed to provide an expanded polytetrafluoroethylene covering that expands and compresses in association with the stent structure as the stent structure expands and contracts. The expandable stent-graft of the present invention may be used for repair and support of body vessel walls.
In preferred embodiments of the present invention, an expandable stent-graft includes a bonded layer of expanded polytetrafluoroethylene covering a stent so that the longitudinal fibrils of the cover are at least substantially extended to adapt to the stent longitudinal expansion when the stent is radially compressed; circumferential fibrils are at least substantially folded to adapt to the stent radial compression when the stent is longitudinally expanded; longitudinal fibrils are at least substantially folded to adapt to the stent longitudinal compression when the stent is radially expanded; and so the circumferential fibrils are at least substantially extended to adapt to the stent radial expansion when the stent is longitudinally compressed.
In other preferred embodiments of the present invention, an expandable stent-graft includes a bonded layer of expanded polytetrafluoroethylene covering a stent so that the inter-nodule distance measured in the longitudinal direction between nodules is increased when the expandable stent-graft is radially compressed; the inter-nodule distance measured in the longitudinal direction between nodules is decreased when the expandable stent-graft is radially expanded; the inter-nodule distance measured in the circumferential direction between nodules is increased when the expandable stent-graft is longitudinally compressed; and so the inter-nodule distance measured in the circumferential direction between nodules is decreased when the expandable stent-graft is longitudinally expanded.
In sum, the present invention relates to an expandable prosthesis having (a) a discontinuous wall defining a lumen adapted to assume a longitudinally contracted position and a longitudinally expanded position; and (b) at least one layer of expanded polytetrafluoroethylene having a first average longitudinal inter-nodule distance in a free state, the layer of polytetrafluorocthylene affixed to the wall such that it has a second average longitudinal inter-nodule distance when the wall is in the longitudinally contracted position, the second average longitudinal inter-nodule distance being less than the first average longitudinal inter-nodule distance. The layer of expanded polytetrafluoroethylene may have (i) an average longitudinal inter-nodule distance of between about 0 and about 50 microns, preferably between about 5 and about 45 or between about 20 and about 30 microns, when the wall is in the longitudinally contracted position, and (ii) an average longitudinal inter-nodule distance of between about 50 and about 150 microns, preferably between about 60 and about 140 or between 80 and about 120 microns, when the wall is in the longitudinally expanded position.
The present invention also relates to an expandable prosthesis having (a) a discontinuous wall defining a lumen adapted to assume a radially contracted position and a radially expanded position; and (b) at least one tubular layer of an expanded polytetrafluoroethylene having a first average circumferential inter-nodule distance in a free state, the layer of polytetrafluoroethylene affixed to the wall such that it has a second average circumferential inter-nodule distance when the wall is in the radially contracted state, the second average circumferential inter-nodule distance being less than the first average circumferential inter-nodule distance. The tubular layer of expanded polytetrafluoroethylene may have (i) an average circumferential inter-nodule distance of between about 0 and about 75 microns, preferably between about 5 and about 70 or between about 20 and about 50 microns, when the wall is in the radially contracted position, and (ii) an average circumferential inter-nodule distance of between about 75 and about 150 microns, preferably between about 80 and about 140 microns or between about 80 and about 120 microns, when the wall is in the radially expanded position.
The present invention also relates to an expandable prosthesis having (a) a discontinuous wall generally defining a lumen adapted to assume a longitudinally expanded position and a longitudinally contracted position; and (b) at least one layer of expanded polytetrafluoroethylene having a first average longitudinal inter-nodule distance in a free state, the layer of polytetrafluoroethylene affixed to the wall such that the polytetrafluoroethylene has a second average longitudinal inter-nodule distance between 0 and 99 percent of the first average longitudinal inter-nodule distance when the wall is in the longitudinally contracted position. The second average longitudinal inter-nodule distance may be between about 20 and about 50 percent of the first average longitudinal inter-nodule distance when the wall is in the longitudinally contracted position.
The present invention also relates to an expandable prosthesis having (a) a discontinuous wall generally defining a lumen adapted to assume a radially expanded position and a radially contracted position; and (b) at least one layer of expanded polytetrafluoroethylene having a first average circumferential inter-nodule distance in a free state, the layer of polytetrafluoroethylene affixed to the wall such that the polytetrafluoroethylene has a second average circumferential inter-nodule distance less than about 50 percent of the first average circumferential inter-nodule distance when the wall is in the radially contracted position. The second average circumferential inter-nodule distance may be less than about 25 percent of the first average circumferential inter-nodule distance when the wall is in the radially contracted position.
The present invention also relates to an expandable prosthesis having (a) a discontinuous wall defining a lumen adapted to assume a radially expanded position and a radially contracted position; and (b) at least one layer of expanded polytetrafluoroethylene having a first average longitudinal inter-nodule distance and a first average circumferential inter-nodule distance in a free state, the layer of the polytetrafluoroethylene affixed to the wall such that the polytetrafluoroethylene has a second average longitudinal inter-nodule distance between 0 and 99 percent of the first average longitudinal inter-nodule distance when the wall is in the radially expanded position and a second average circumferential inter-nodule distance less than about 50 percent of the first average circumferential inter-nodule distance when the wall is in the radially contracted position. The second average longitudinal inter-nodule distance may be between about 20 and about 50 percent of the first average longitudinal inter-nodule distance, and the second average circumferential inter-nodule distance may be less than about 25 percent of the first average circumferential inter-nodule distance.
The present invention also relates to an expandable stent-graft having (a) a braided self-expanding stent characterized by a longitudinal shortening upon radial expansion from a first longitudinal stent length to a second longitudinal stent length; and (b) at least one tubular layer of biaxially oriented expanded polytetrafluoroethylene comprising nodules and fibrils affixed to the stent characterized by a shortening of average longitudinal inter-nodule distance upon radial expansion from a first average longitudinal inter-nodule distance to a second average longitudinal inter-nodule distance; wherein the ratio of first longitudinal stent length to second longitudinal stent length is within about 25 percent of, and is preferably substantially the same as, the ratio of first average longitudinal inter-nodule distance to a second average inter-nodule distance. The present invention also relates an expandable stent-graft having (a) a braided self-expanding stent characterized by a longitudinal shortening upon radial expansion; (b) at least one layer of uniaxially oriented expanded polytetrafluoroethylene affixed to the stent, the polytetrafluoroethylene characterized by having substantially no nodules.
The present invention also relates to a method of making an expandable prosthesis including (a) providing a self-expanding braided stent having a longitudinal orientation in an at least partially radially expanded state; (b) providing at least one layer of expanded polytetrafluoroethylene having a longitudinal orientation and a first average longitudinal inter-nodule distance in a free state; (c) longitudinally compressing the layer of expanded polytetrafluoroethylene so that the resulting longitudinally compressed layer has a second average longitudinal inter-nodule distance which is less than the first average longitudinal inter-nodule distance; and (d) affixing the longitudinally compressed layer of expanded polytetrafluoroethylene to the self-expanding braided stent in the at least partially radially expanded state such that the longitudinal orientations of the stent and layer of expanded polytetrafluoroethylene substantially correspond with one another.