Medical device suitable for location in a body lumen

Abstract

A medical device suitable for location in a body lumen is movable between a first loaded configuration and a second loaded configuration. The device has an unloaded configuration which is intermediate the first loaded configuration and the second loaded configuration. The device can be a stent for deployment in a blood vessel.

1 . A method of stenting a body lumen, comprising:
 deploying and expanding a stent in a body lumen, the stent having a diameter, the body lumen being deformable between an unloaded state and a loaded state;   wherein the stent is one which, after deployment and expansion, is deformable between a first loaded configuration and a second loaded configuration and has an unloaded configuration intermediate the first loaded configuration and the second loaded configuration;   wherein in said unloaded and second loaded configurations at least part of the longitudinal axis of the stent is substantially helically shaped and has an amplitude and wherein in the second loaded configuration the amplitude of the helical longitudinal axis divided by the diameter of the stent is greater than in the unloaded configuration;   and wherein the deploying comprises deploying the stent in the body lumen so that when the body lumen is in the unloaded state the stent is in the first loaded configuration, and when the body lumen is in the loaded state the stent is in the second loaded configuration.   
     
     
         2 . A method as claimed in  claim 1 , wherein the pitch of the helical longitudinal axis is less in the second loaded configuration than in the unloaded configuration. 
     
     
         3 . A method as claimed in  claim 1 , wherein in the first loaded configuration at least part of the longitudinal axis of the stent is substantially helically shaped and the amplitude of the helical longitudinal axis divided by the diameter of the stent is less than in the unloaded configuration. 
     
     
         4 . A method as claimed in  claim 3 , wherein the pitch of the helical longitudinal axis is greater in the first loaded configuration than in the unloaded configuration. 
     
     
         5 . A method as claimed in  claim 1 , wherein in the unloaded configuration the amplitude of the helical longitudinal axis divided by the diameter of the stent is in the range of 0.3 to 0.9. 
     
     
         6 . A method as claimed in  claim 1 , wherein in the first loaded configuration at least part of the longitudinal axis of the stent is helical and the amplitude of the helical longitudinal axis divided by the diameter of the stent is in the range of 0 to 0.5. 
     
     
         7 . A method as claimed in  claim 1 , wherein in the second loaded configuration the amplitude of the helical longitudinal axis divided by the diameter of the stent is 0.5 or greater. 
     
     
         8 . A method of stenting a body lumen, comprising:
 deploying and expanding a stent in a body lumen such that it is in a deployed, expanded configuration; and when the stent is in the deployed, expanded configuration:   deforming the stent to a first loaded configuration when the body lumen bends to an unloaded state thereof;   deforming the stent to a second loaded configuration when the body lumen bends to a loaded state thereof; and   wherein the stent has an unloaded configuration intermediate the first and second loaded configurations and wherein in the unloaded and second loaded configurations at least part of the longitudinal axis of the stent is substantially helically shaped, wherein the amplitude of the helical longitudinal axis divided by the diameter of the stent is greater in the second loaded configuration than in the unloaded configuration.   
     
     
         9 . A method of stenting a body lumen, comprising:
 deploying and expanding a stent in a body lumen, the body lumen being deformable between an unloaded state and a loaded state;   wherein the stent is one which, after deployment and expansion, is deformable between a first loaded configuration and a second loaded configuration and has an unloaded configuration intermediate the first loaded configuration and the second loaded configuration;   wherein in said unloaded configuration at least part of the longitudinal axis of the stent is curved;   and wherein the deploying comprises deploying the stent in the body lumen so that when the stent is deformed through a curve angle of 45 degrees between the first loaded configuration and the second loaded configuration, the maximum strain in the stent, at any stage at or between the first and second loaded configurations, is less than or equal to 0.4%.   
     
     
         10 . A method as claimed in  claim 1 , wherein deforming the stent comprises bending the stent between the first loaded configuration and the second loaded configuration. 
     
     
         11 . A method as claimed in  claim 1 , wherein deforming the stent comprises twisting the stent between the first loaded configuration and the second loaded configuration. 
     
     
         12 . A method as claimed in  claim 1 , wherein deforming the stent comprises compressing the stent between the first loaded configuration and the second loaded configuration. 
     
     
         13 . A method as claimed in  claim 1 , wherein the maximum strain is less than or equal to 0.3%. 
     
     
         14 . A method as claimed in  claim 1 , wherein when the stent is axially compressed by 6% from the first loaded configuration to the second loaded configuration, the maximum strain in the stent, at any stage at or between the first and second loaded configurations, is less than or equal to 0.7%. 
     
     
         15 . A method as claimed in  claim 1 , wherein the unloaded configuration is approximately midway between the first loaded configuration and the second loaded configuration. 
     
     
         16 . A method as claimed in  claim 1 , further comprising aligning the stent relative to a body lumen. 
     
     
         17 . A method as claimed in  claim 16 , wherein aligning the stent comprises aligning a marker or the stent with the body lumen. 
     
     
         18 . A method as claimed in  claim 1 , wherein the body lumen is a blood vessel. 
     
     
         19 . A method as claimed in  claim 1 , wherein the stent has a longitudinal axis with a length of at least 50 mm. 
     
     
         20 . A method as claimed in  claim 1 , wherein the stent is made of Nitinol.