Stent delivery catheter

Abstract

A self-expanding stent delivery assembly includes a shaft having a proximal end, a distal end, a distal region, a lumen, and a longitudinal axis. A retractable sheath having an outer surface, a proximal end and a distal end is co-axially disposed around the shaft distal region. A stent is disposed co-axially between the shaft and the retractable sheath. A tubular tapered tip is affixed to the retractable sheath distal end. The tubular tapered tip has an elongate region predisposed to fracturing. Methods of delivering a self-expanding stent are also described.

1 . A stent delivery assembly comprising:
 a shaft having a proximal region and a distal region;   a self-expanding stent disposed about at least a portion of the distal region of the shaft;   a sheath having a proximal end and a distal end, the sheath disposed around at least the distal region of the shaft and the self-expanding stent, wherein the sheath is configured to be retracted from the self-expanding stent to deploy the self-expanding stent; and   a tubular tapered tip coupled to the distal end of the sheath, the tubular tapered tip having a region predisposed to fracturing.   
   
   
       2 . The stent delivery assembly of  claim 1 , wherein the region predisposed to fracturing is configured to fracture when the sheath is retracted from the stent. 
   
   
       3 . The stent delivery assembly of  claim 1 , further comprising a stop member coupled to the shaft and positioned proximally of the self-expanding stent. 
   
   
       4 . The stent delivery assembly of  claim 1 , wherein the tubular tapered tip has a plurality of elongate regions predisposed to fracturing, wherein each elongate region predisposed to fracturing are co-planar. 
   
   
       5 . The stent delivery assembly of  claim 1 , wherein the elongate region predisposed to fracturing includes a line of perforations. 
   
   
       6 . The stent delivery assembly of  claim 1 , wherein the tubular tapered tip has a first thickness and the elongate region predisposed to fracturing has a second thickness that is less than the first thickness. 
   
   
       7 . The stent delivery assembly of  claim 1 , wherein the tubular tapered tip is formed of a first material having a first tensile strength and the elongate region predisposed to fracturing is formed of a second material having a second tensile strength that is less than the first tensile strength. 
   
   
       8 . The stent delivery assembly of  claim 1 , further comprising a guidewire disposed within the shaft lumen. 
   
   
       9 . The stent delivery assembly of  claim 8 , wherein the tubular tapered tip has a distal end defining a tip opening, the tip opening sized and configured to surround the guidewire. 
   
   
       10 . A stent delivery assembly comprising:
 a shaft having a proximal region and a distal region;   a stent disposed about at least a portion of the distal region of the shaft;   a sheath having a proximal end and a distal end, the sheath moveable between at least a first position and a second position, when in the first position, the sheath is disposed around the distal region of the shaft and the self-expanding stent, when the sheath is in the second position, the sheath is disposed around the distal region of the shaft with the distal end of the shaft being proximal of a proximal end of the stent, wherein the movement of the sheath between the first position and the second position deploys the stent; and   a tubular tapered tip coupled to the distal end of the sheath, the tubular tapered tip having a region predisposed to fracturing, wherein moving the sheath from the first position to the second position causes the region predisposed to fracturing to fracture.   
   
   
       11 . The stent delivery assembly of  claim 10 , wherein the stent is a self-expanding stent. 
   
   
       12 . The stent delivery assembly of  claim 10 , further comprising a stop member coupled to the shaft and positioned proximally of the stent. 
   
   
       13 . The stent delivery assembly of  claim 10 , wherein the elongate region predisposed to fracturing includes a line of perforations. 
   
   
       14 . The stent delivery assembly of  claim 10 , wherein the tubular tapered tip has a first thickness and the elongate region predisposed to fracturing has a second thickness that is less than the first thickness. 
   
   
       15 . The stent delivery assembly of  claim 10 , wherein the tubular tapered tip is formed of a first material having a first tensile strength and the elongate region predisposed to fracturing is formed of a second material having a second tensile strength that is less than the first tensile strength. 
   
   
       16 . The stent delivery assembly of  claim 10 , further comprising a guidewire disposed within the shaft lumen. 
   
   
       17 . The stent delivery assembly of  claim 16 , wherein the tubular tapered tip has a distal end defining a tip opening, the tip opening sized and configured to surround the guidewire. 
   
   
       18 . A method of delivering a self-expanding stent to a target site in a vessel, the method comprising:
 positioning a stent delivery device at the target site in the vessel, the stent delivery device comprising:
 a self-expanding stent disposed about at least a portion of the distal region of the shaft; 
 a sheath having a proximal end and a distal end, the sheath disposed around at least the distal region of the shaft and the self-expanding stent, wherein the sheath is configured to be retracted from the self-expanding stent to deploy the self-expanding stent; and 
 a tubular tapered tip coupled to the distal end of the sheath, the tubular tapered tip having a region predisposed to fracturing; and 
   retracting the sheath from the stent to deploy the stent at the target site, wherein the retracting causes the region predisposed to fracturing to fracture.   
   
   
       19 . The method of  claim 18 , wherein the self-expanding stent expands when the sheath is retracted from the self-expanding stent. 
   
   
       20 . The method of  claim 18 , further comprising placing a guidewire across the target site prior to placing the stent delivery device at the target site, wherein the tubular tapered tip has a distal end defining a tip opening, the tip opening sized and configured to pass the guidewire therethrough.