Delivery and deployment systems for bifurcated stent grafts

Abstract

A system for endoluminal delivery of a medical device, wherein the medical device includes a bifurcated stent graft having a trunk, a first leg and a second leg shorter than the first leg. The system includes a sheath having a tubular wall having a cylindrical inner surface defining a lumen for receiving the stent graft therein to constrain the stent graft toward a delivery configuration suitable for endoluminal delivery, and a generally cylindrical core member extending through the lumen. The core member has a first annular surface for engaging an end of the first leg. The core has a second annular surface for engaging an end of the second leg while at least the end of the second leg remains constrained by the sheath.

What is claimed is: 
     
         1 . An endoluminal delivery system comprising:
 a bifurcated stent graft having a trunk, a first leg, and a second leg shorter than the first leg;   a sheath having a tubular wall having an inner surface defining a lumen for receiving the stent graft therein to constrain the stent graft toward a delivery configuration suitable for endoluminal delivery; and   a core member having a first surface and a second annular surface, the core member extending into a lumen of the first leg such that the first surface abuts an end of the first leg, the second surface positioned within the lumen of the first leg such that the first leg is disposed between the second surface and the second leg, and wherein the second leg, while being constrained by the sheath, enhances column strength in an axial direction along the core member between the first surface and the second surface to resist axial crumpling of the stent graft.   
     
     
         2 . The system of  claim 1 , wherein the sheath is axially displaceable relative to the core member, and the second leg is configured to enhance the column strength during an axial displacement of the sheath relative to the core. 
     
     
         3 . The system of  claim 2 , wherein the axial displacement of the sheath relative to the core causes an outward expansion of the stent graft from the delivery configuration to an expanded configuration to engage with vessel walls of a patient. 
     
     
         4 . The system of  claim 3 , further comprising a secondary sheath configured to limit expansion of the stent graft to an intermediate configuration larger than the delivery configuration and smaller than the expanded configuration. 
     
     
         5 . The system of  claim 1 , wherein the core member is generally cylindrical and includes a first section having a first diameter and a second section having a second diameter, the first diameter being larger than the second diameter, and wherein the first surface is a first annular surface and defines a transition between an outer surface of the first section and an outer surface of the second section. 
     
     
         6 . The system of  claim 5 , wherein the first annular surface is normal relative to a longitudinal axis of the core member. 
     
     
         7 . The system of  claim 5 , wherein the core member includes a third section having a third diameter, the second diameter being larger than the third diameter, and wherein the second surface defines a transition between the outer surface of the second section and an outer surface of the third section. 
     
     
         8 . The system of  claim 7 , wherein a difference between the second diameter and the third diameter is at least twice the sum of a thickness of the first leg and twice a thickness of the second leg. 
     
     
         9 . The system of  claim 7 , wherein the second annular surface is normal relative to a longitudinal axis of the core member. 
     
     
         10 . The system of  claim 7 , wherein the first, second, and third sections of the core member are coaxial. 
     
     
         11 . The system of  claim 1 , wherein the first surface and the second surface are parallel.