Prosthesis delivery system with dilating tip

Abstract

This invention provides prosthesis delivery systems with tips constructed to permit both easier advance into the body and easier removal from the body after expanding the prosthesis. The tip includes a distal taper that can gently widen a lumen during advance in instances where the lumen is narrower than the tip and a proximal taper that can gently widen the lumen on retraction in instances where the prosthesis does not immediately expand the lumen to provide clearance for the larger diameter tip.

What is claimed is:  
     
         1 . A system for delivering a prosthesis into the body of a patient, comprising: 
 an elongated catheter having a proximal end that remains outside the body, a distal end, and a supporting portion supporting a prosthesis in a radially compacted form for delivery of the prosthesis to a desired location inside the body, and    an dilating tip distal of said prosthesis, said tip having a maximum diameter about equal to or greater than the radially compacted prosthesis, and being shaped to include a distal portion that smoothly extends distally to smaller diameters, and a proximal portion that smoothly extends proximally to smaller diameters for enhancing withdrawal after expanding said stent.    
     
     
         2 . The system of    claim 1    wherein said distal and proximal portions of said tip include tapers to smaller diameter.  
     
     
         3 . The system of    claim 2    wherein the tip is formed with a proximal taper an angle of 20 degrees or less.  
     
     
         4 . The system of    claim 1    wherein the tip is smoothly shaped in the proximal portion without abrupt edges.  
     
     
         5 . The system of    claim 4    wherein said prosthesis is expandable to diameters less than said maximum diameter of said tip and said proximal portion of said tip engages said prosthesis during withdrawing said catheter proximally to widen the prosthesis for removing the catheter.  
     
     
         6 . The system of    claim 2    wherein the proximal portion includes taper of about 20° or less.  
     
     
         7 . The system of    claim 1    wherein said tip has a maximum diameter of about 8 mm.  
     
     
         8 . The system of    claim 1    wherein the proximal and distal portions have an axial length greater than said maximum diameter of the tip.  
     
     
         9 . The system of    claim 1    wherein said tip has transition regions between portions of different diameter and said transition regions are smoothly formed, without abrupt edges.  
     
     
         10 . The system of    claim 1    wherein said prosthesis is self-expanding.  
     
     
         11 . The system of    claim 10    further comprising a retractable protective sheath over said prosthesis, that engages said tip to form a seal that protects said prosthesis from exposure to body fluids during delivery into the body.  
     
     
         12 . The system of    claim 11    wherein said protective sheath engages said tip at a step region, which has smooth transitions to to different diameters.  
     
     
         13 . The system of    claim 1    including a sheath with a flexible proximal portion having a smaller diameter than a distal portion positioned over said sheath during delivery into the body.  
     
     
         14 . A method for delivering a prosthesis into the body of a patient, comprising: 
 providing an elongated catheter having a proximal end that remains outside the body, a distal end, and a supporting portion supporting a prosthesis in a radially compacted form, said catheter further including a dilating tip distal of said supporting portion and having a diameter about equal to or greater than the radially compacted prosthesis, and being shaped to include a distal portion that smoothly extends distally to smaller diameters, and a proximal portion that smoothly extends proximally to smaller diameters for enhancing withdrawal after expanding said stent,    placing said catheter into a body lumen and positioning said prosthesis at a desired location,    expanding said prosthesis to a diameter no larger than said maximum diameter of said tip,    withdrawing said catheter to engage the proximal portion of the tip and the prosthesis, and    continuing to withdraw said catheter so said tip widens the passage through the prosthesis so the catheter can be removed from the body.    
     
     
         15 . The method of    claim 14    comprising, 
 selecting a self-expanding prosthesis to provide axial force to the interior of said lumen to fully expand said lumen after an extended period of time, and  
 withdrawing said catheter prior to fully expanding said prosthesis.  
 
     
     
         16 . The method of    claim 15    or    16    comprising crossing a region of a lumen consticted to a diameter smaller than the maximum diameter of the tip by urging the distal or proximal portion of said tip against said region to widen said region.