Expandable stent having a stabilized portion

Abstract

An expandable stent having a covering which exhibits the characteristic of being normally dissolvable in blood, but upon being activated, becomes inert to blood. The stent may be placed across the neck of an aneurysm to seal the aneurysm and thereafter the portion of the covering of the stent across the neck of the aneurysm is activated to become inert to blood and the balance of the covering dissolves to permit blood to flow to adjacent vessels.

1 . An aneurysm treatment device comprising: 
 an expandable stent which takes the form of a small diameter skeletal tubular member having a thin wall, said wall of said skeletal tubular member including a plurality of cells which are formed by a plurality of interconnected strut members; and,    a covering extending over a portion of the expandable stent, said covering exhibiting the characteristic of being normally dissolvable when in contact with bodily fluids but upon being stabilized by applying an activating agent to said covering, becoming inert to bodily fluids.    
     
     
         2 . An aneurysm treatment device as defined in  claim 1 , wherein said expandable stent takes the form of a metallic skeletal tubular member and said covering is formed from a polymer.  
     
     
         3 . An aneurysm treatment device as defined in  claim 2 , wherein the covering is formed of a material which polymerizes when it comes into contact with the activating agent.  
     
     
         4 . An aneurysm treatment device as defined in  claim 3 , wherein said covering takes the form of sodium alginate and the activating agent takes the form of a solution comprising calcium ions.  
     
     
         5 . An aneurysm treatment device as defined in  claim 4 , wherein the covering takes the form of a thin film of sodium alginate material disposed on an outer surface of said expandable stent.