Percutaneous implantation of partially covered stents in aneurysmally dilated arterial segments with subsequent embolization and obliteration of the aneurysm cavity

Abstract

A low profile, abdominal aortic aneurysm exclusion device with iliac vessel extensions. The present invention includes a sectional, bifurcated stent that forms part of an endoluminal prosthesis to eliminate or reduce the risk of rupture of aortic aneurysms as well as an apparatus and a method for introducing the bifurcated stent in sections into the vasculature and assembling the sections in situ to form a “scaffold” for introduction of material to re-endothelialize and/or occlude the aneurysm cavity. After trans-stent embolization of the aneurysm cavity with thrombogenic material, laminar flow stimulates endothelialization of the stent lumen. Subsequent organization and fibrosis of the peri-stent thrombus reinforces the wire-mesh or etched metal tubular scaffold comprising the stent and serves to stabilize and shrink the aneurysm. A single stent deployed with the same method may be used in non-bifurcated vessels.

1 . A method for implanting a tubular stent for treatment of a vascular aneurysm in a bifurcated vessel comprising the steps of: 
 utilizing a percutaneous femoral puncture to insert a first stent encased in a first sheath into the femoral artery of a patient, said stent constructed with a proximal end first inserted;    directing said first stent encased in said first sheath to the site of an aneurysm in the vessel;    withdrawing said first sheath leaving said first stent in place at the site of the aneurysm;    inserting second and third stents whose proximal portions are the larger cross section of each of said second and third stents and said proximal portions frustro-conically tapering to a smaller cross section proceeding distally in each of said second and third sheaths, wherein said second and third stents are encased in respective second and third sheaths to contact and enter said first stent in place at the site of the aneurysm; and    withdrawing said second and third sheaths to leave the proximal ends of said second and third stents to expand against each other and against the walls of said first sheath and with the distal ends of said first and second sheath directed in each branch of said bifurcated vessel    
     
     
         2 . The method recited in  claim 1  further comprising inserting vascular embolization coils, foam, gel, glue or other thrombogenic substances or devices through said percutaneous femoral puncture and directing said coils, substances or devices to the aneurysm cavity site.  
     
     
         3 . The method recited in  claim 1  wherein said aneurysm is located at or near the bifurcation of the abdominal aorta and said second and third stents approach from the bifurcation.  
     
     
         4 .- 11 . (canceled)  
     
     
         12 . An implantable stent system comprising an elongate, tubular main stent and first and second substantially tubular bifurcation stents, each of said bifurcation stents being comprised of a memory retentive material compressible for insertion of the proximal end thereof into the distal end of said main stent for subsequent expansion into engagement with the inside wall of said main stent, the proximal end of each of said bifurcation stents being frustro-conically tapered semi-circular shape with the larger diameter semicircular cross section at the proximal end and tapering to a smaller cross section proceeding distally, the semi-circular cross section at the proximal ends juxtaposed with the flat sections of said semi-circular cross sections of said proximal ends of said bifurcation stents contacting each other when said bifurcation stents are expanded into engagement with the inside wall of said main stent and against each other.  
     
     
         13 . A method of treating an aneurysm in a bifurcated blood vessel comprising the steps of: 
 inserting a tubular main stent into the lumen of a bifurcated blood vessel having an aneurysm therein with one end proximal to the aneurysm and the other end distal to the aneurysm;    compressing first and second bifurcation stents;    inserting a proximal end of each of the compressed first and second bifurcation stents into the end of the main stent distal to the aneurysm with the distal ends of each of said first and second bifurcation stents residing in the lumens of the respective first and second bifurcations of the blood vessel; and    expanding the proximal ends of each of the compressed first and second bifurcation stents into engagement with the inside wall of the distal end of the main stent and with each other, the expanded proximal ends of each of the first and second bifurcation stents defining a tapered, semi-circularly shaped end, the tapered portions of each of the first and second bifurcation stents being the portion of the first and second bifurcation stents contacting the other of the first and second bifurcation stents when the first and second bifurcation stents are expanded in the distal end of the main stent.    
     
     
         14 . An implantable stent system for treatment of an aneurysm in a bifurcated blood vessel comprising first and second generally substantially cylindrical bifurcation stents, the proximal end of each of said bifurcation stents being frustro-conically tapered with the end thereof being formed in the shape of a semi-circle having a flat side with the wall of the frustro-conical end of each of said bifurcation stents being tapered to the semi-circularly shaped end and the second end of each first and second bifurcation stents being of cylindrical cross section conformal with the distal cross section of said proximal first and second ends and an elongate, tubular main stent, the frustro-conically-shaped end of each of said first and second bifurcation stents being inserted into one end of said main stent with the flat side of the tapered walls of each of said bifurcation stents in contact with each other and with the semi-circularly-shaped end in contact with the inside wall of said main stent, the bifurcation stents assuming the cross sectional shape of the lumen of said main stent, each of said first and second bifurcation stents being comprised of a memory retentive material that is compressed for insertion into the end of said main stent for subsequent expansion into contact with the inside wall of said main stent and the other of said first and second bifurcation stents to affirmatively retain said first and second bifurcation stents in the end of said main stent and to occupy all available space in the end of said main stent.