Stents and catheters having improved stent deployment

Abstract

An implant delivery system and method comprises an implant, for example, a stent, and a delivery catheter. The stent has a scaffold with a coating or a shell that retains the scaffold in a collapsed configuration. The coating or shell is made of a material that dissolves or biodegrades upon exposure to a dissolution or biodegradation media. The stent is used with an implant delivery system which has a catheter with a catheter, wherein the stent is mounted on the catheter shaft. The catheter shaft is configured to be withdrawn through the patient's vessel when the scaffold is in its expanded configuration. Advantageously, the implant is thereby prevented from changing length during implant delivery and implant deployment.

What is claimed is: 
     
         1 - 21 . (canceled) 
     
     
         22 : An implant delivery system for deploying a stent in a body lumen, the system comprising:
 a catheter shaft;   a stent mounted on the catheter shaft, the stent including a scaffold having a collapsed configuration and an expanded configuration, the stent including a coating surrounding the scaffold that retains the scaffold in the collapsed configuration, the coating being formed of a material that dissolves upon exposure to a dissolution media, the scaffold being expandable from the collapsed configuration to the expanded configuration through exposure of the coating to the dissolution media; and   a tubular sheath covering the stent while in a collapsed configuration, the tubular sheath being movable to expose the coating and enable the scaffold to expand from the collapsed configuration to the expanded configuration as the coating dissolves upon exposure to the dissolution media.   
     
     
         23 : The implant delivery system of  claim 22 , wherein the coating is formed into a shell. 
     
     
         24 : The implant delivery system of  claim 22 , wherein the coating comprises a bioactive material selected from the group consisting of antirestenotic agents, anti-inflammatory agents, antithrombotic agents, antiatheromatic (antiatheroma) agents, and antioxidative agents. 
     
     
         25 : The implant delivery system of  claim 22 , wherein the scaffold is self-expanding. 
     
     
         26 : The implant delivery system of  claim 25 , wherein the scaffold self-expands to the expanded configuration as the coating dissolves. 
     
     
         27 : The implant delivery system of  claim 22 , wherein the scaffold is balloon-expandable. 
     
     
         28 : The implant delivery system of  claim 27 , wherein a balloon interposed between the scaffold and the catheter shaft expands to expand the scaffold to the expanded configuration when the coating dissolves. 
     
     
         29 : The implant delivery system of  claim 22 , wherein the coating maintains the scaffold in the collapsed configuration wherein the scaffold has an unexpanded diameter and a fixed length prior to deployment. 
     
     
         30 : The implant delivery system of  claim 22 , wherein the coating is supported on at least one of an inner and an outer surface of the scaffold. 
     
     
         31 : The implant delivery system of  claim 22 , wherein the tubular sheath is axially slidable relative to the stent. 
     
     
         32 : The implant delivery system of  claim 22 , wherein the coating includes at least one of preplaced slits, slots, and local thinning of a wall thickness of the coating.