Methods for delivering, repositioning and/or retrieving self-expanding stents

A method of delivering a shape memory stent having a transition temperature at or below body temperature to, and deploying the stent at, a diseased tubular area within the body, comprising the steps of:

• mounting the shape memory stent in a collapsed condition on an inflatable balloon in a collapsed condition coupled to a catheter assembly, said balloon having a chamber and having an outer heat transfer wall, such that the heat transfer wall is in local heat transfer relationship with the stent;
• delivering the stent in said collapsed condition on said collapsed balloon to a region of the diseased tubular area in the body;
• commencing a circulating flow into and from said chamber of said balloon at least as early as the time the stent in its collapsed condition on the collapsed balloon has been delivered to a region of the diseased tubular area;
• said circulating flow comprising infusing a flow of cooling thermal fluid from a proximal end of the catheter assembly into said chamber of said balloon, and withdrawing a flow of cooling thermal fluid from said chamber of said balloon to the proximal end of the catheter assembly;
• if necessary, adjusting the position of the stent in said collapsed condition on said collapsed balloon in said diseased tubular area;
• controlling the expansion of said stent into supporting the engagement of the wall of the diseased tubular area by adjusting the temperature and/or rate of the inflow of cooling thermal fluid into said chamber.

A method of delivering a shape memory stent having a transition temperature at or below body temperature to, and deploying the stent at, a diseased tubular area in the body comprising the steps of:

• mounting the shape memory stent in a collapsed condition on an inflatable balloon in a collapsed condition coupled to a catheter assembly, said balloon having a chamber having an outer thermal transfer wall, such that the thermal transfer wall is in local heat transfer relationship with the stent;
• delivering the stent in said collapsed condition on said collapsed balloon to a region of the narrowing tubular area in the body;
• commencing a circulating flow into and from said balloon at least as early as the time the stent in its collapsed condition on the collapsed balloon has been delivered to a region of the diseased tubular area, said circulating flow comprising an inflow of cooling thermal fluid from a proximal end of the catheter assembly into said chamber of said balloon, and an outflow from the chamber of said balloon to the proximal end of the catheter assembly;
• if necessary, adjusting the position of the stent in said collapsed condition on said balloon in said diseased tubular area;
• controlling the expansion of the stent into supporting engagement with the wall of the diseased tubular area by adjusting the rate and/or the temperature of the inflow of cooling thermal fluid into said chamber;
• and during said controlled expansion step, at least partially expanding the balloon.

A method of capturing a two-way shape memory stent having first and second transition temperatures which is already deployed in supporting engagement with a vessel wall at a first position for repositioning or retrieval comprising the steps of:

• providing an expandable and collapsible thermal transfer device in a collapsed condition on a catheter assembly, said expandable thermal transfer device including a chamber having a thermal transfer wall;
• introducing said expandable thermal transfer device in its collapsed condition on said catheter assembly into the lumen of the deployed stent;
• expanding the expandable thermal transfer device until its thermal transfer wall is in local thermal transfer relationship with the deployed stent;
• circulating a cooling thermal fluid from a proximal end region of said catheter assembly into said chamber of said expandable thermal transfer device and from said chamber of said thermal transfer device to said proximal end region of said catheter assembly to thereby cool said deployed stent in local thermal transfer relationship with said thermal transfer wall to cause the temperature of the stent to decrease to or below the second transition temperature to thereby become at least partially collapsed, soft and pliable;
• capturing said at least partially collapsed and softened stent by stent-capturing means to capture the stent to the catheter assembly.

A method of capturing a two-way shape memory stent which is already deployed in supporting engagement with a vessel wall, for repositioning or retrieval comprising the steps of:

• providing a thermal transfer device on a catheter assembly, said thermal transfer device having a thermal transfer surface;
• introducing the thermal transfer device into the lumen of the deployed stent;
• positioning the thermal transfer device until the thermal transfer surface is in local thermal transfer relationship with the deployed stent;
• reducing the temperature of the thermal transfer device to thereby cool said deployed stent in local heat transfer relationship with said thermal transfer surface to cause the temperature of the stent to decrease to or below the second transition temperature to thereby become at least partially collapsed, soft and pliable, and separate from the vessel wall and;
• capturing the at least partially collapsed and softened stent by stent-capturing means to capture the stent to the catheter assembly.