Strain Management in Stent Delivery System

Abstract

A delivery system for a medical implant and a method of delivering the medical implant. The delivery system includes an inner catheter and an outer catheter. The inner catheter includes a wire coil disposed between an inner tube and an outer tube, the wire coil having gaps between turns of the coil at a proximal and a distal region thereof. The outer catheter is disposed about the inner catheter. The system includes a flow path for liquid from a proximal end to a distal end thereof, the flow path including a radially extending portion through the gaps. The method includes inserting the delivery system into a body lumen, injecting visualizing fluid into the proximal end of the system, the visualizing fluid moving through the flow path and exiting the distal end of the system, and retracting the outer catheter to release the medical implant.

What is claimed is: 
     
         1 . A delivery system for a medical implant comprising:
 an inner catheter including a wire coil disposed between an inner tube and an outer tube, the wire coil having a plurality of gaps between turns of the coil at a proximal and a distal region of the coil;   an outer catheter disposed about the inner catheter;   a pusher element abutting a distal end of the wire coil;   and   a flow path for liquid from a proximal end through a distal end of the system past a distal end of the inner tube of the inner catheter, the flow path including a portion passing through the gaps.   
     
     
         2 . The delivery system of  claim 1  wherein the outer tube is disposed over an intermediate region of the wire coil having a closed-coil structure. 
     
     
         3 . The delivery system of  claim 2  wherein the outer tube comprises PTFE configured to fit tightly over the wire coil preventing adjacent turns of the coil from overlapping. 
     
     
         4 . The delivery system of  claim 3  wherein the flow path in the intermediate region is bounded by the inner tube and the outer tube. 
     
     
         5 . The delivery system of  claim 4  wherein
 a distal end of the wire coil is disposed over at least a section of the shoulder portion to secure the position of the pusher element with respect to the inner tube, 
 and 
 a distal region of the inner tube defines a medical implant bed. 
 
     
     
         6 . The delivery system of  claim 1  further comprising a self-expanding stent, having a radially expanded configuration and a radially compressed configuration, wherein the stent is disposed about a portion of the inner catheter and maintained in the collapsed configuration by the outer catheter. 
     
     
         7 . The delivery system of  claim 6  wherein the pusher element is attached to the inner tube proximal of a medical implant bed, the pusher element including a flange portion and a shoulder portion. 
     
     
         8 . The delivery system of  claim 7  wherein an adhesive is disposed between at least a section of the shoulder portion and the inner tube. 
     
     
         9 . The delivery system of  claim 8  wherein a distal end of wire coil is disposed over at least a section of the shoulder portion to secure the position of the pusher element with respect to the inner tube. 
     
     
         10 . The delivery system of  claim 2  wherein the flow path in the intermediate region is bounded by the inner tube and the outer tube. 
     
     
         11 . The delivery system of  claim 10  further comprising a self-expanding stent, having a radially expanded configuration and a radially compressed configuration, wherein the stent is disposed about a portion of the inner catheter and maintained in the collapsed configuration by the outer catheter. 
     
     
         12 . The delivery system of  claim 11  wherein the pusher element is attached to the inner tube proximal of a medical implant bed, the pusher element including a flange portion and a shoulder portion. 
     
     
         13 . The delivery system of  claim 2  wherein the pusher element is attached to the inner tube proximal of a medical implant bed, the pusher element including a flange portion and a shoulder portion. 
     
     
         14 . The delivery system of  claim 13  wherein the flow path in the intermediate region is bounded by the inner tube and the outer tube. 
     
     
         15 . The delivery system of  claim 5  wherein the flow path in the intermediate region is bounded by the inner tube and the outer tube. 
     
     
         16 . The delivery system of  claim 15  wherein the pusher element is attached to the inner tube proximal of a medical implant bed, the pusher element including a flange portion and a shoulder portion. 
     
     
         17 . The delivery system of  claim 7  wherein a distal end of wire coil is disposed over at least a section of the shoulder portion to secure the position of the pusher element with respect to the inner tube. 
     
     
         18 . The delivery system of  claim 4  wherein a distal region of the inner tube defines a medical implant bed. 
     
     
         19 . The delivery system of  claim 1  wherein
 a distal end of the wire coil is disposed over at least a section of the shoulder portion to secure the position of the pusher element with respect to the inner tube, 
 and 
 a distal region of the inner tube defines a medical implant bed. 
 
     
     
         20 . The delivery system of  claim 4  wherein
 a distal end of the wire coil is disposed over at least a section of the shoulder portion to secure the position of the pusher element with respect to the inner tube, 
 and 
 a distal region of the inner tube defines a medical implant bed.