Removable stent for body lumens

Abstract

A removable stent for implantation into a lumen in a human body. The stent is made from a soft, flexible fiber having an outer surface. An outer bioabsorbable/degradable coating is applied to the outer surface of the filament causing it to become rigid. The coating softens in vivo through absorption and/or degradation such that the stent is readily passed or removed from the lumen as a softened filament after a pre-determined period of time through normal flow of body fluids passing through the lumen or by manual removal.

We claim:  
     
         1 . A stent, comprising: 
 a helical structure having a plurality of coils, said structure having a longitudinal axis and said coils having a pitch, said structure having an internal longitudinal passage wherein said structure is made from a filament having a cross-section and an outer surface, said filament comprising: 
 a soft flexible elongated member having an outer surface; and  
 a bioabsorbable or biodegradable polymeric outer coating on the outer surface of the member;  
   wherein, the polymeric coating has sufficient mechanical integrity to effectively maintain the flexible member in a helical configuration, until the coating has sufficiently been degraded or absorbed in vivo to effectively convert the helical structure back into a soft, elongated member.    
     
     
         2 . The stent of  claim 1  wherein the coating comprises a melt polymer.  
     
     
         3 . The stent of  claim 1 , wherein the coating comprises a solution polymer.  
     
     
         4 . The stent of  claim 1  wherein the filament comprises a surgical suture.  
     
     
         5 . The stent of  claim 4 , wherein the suture comprises a monofilament.  
     
     
         6 . The stent of  claim 4 , wherein the suture comprises a multifilament.  
     
     
         7 . The stent of  claim 4 , wherein the suture comprises a non-absorbable suture.  
     
     
         8 . The stent of  claim 4  wherein the suture comprises an absorbable suture.  
     
     
         9 . The stent of  claim 1 , wherein the coating comprises a polymer made from monomers selected from the group consisting of lactide, glycolide, para-dioxanone, caprolactone, and trimethylene carbonate, caprolactone, blends thereof and copolymers thereof  
     
     
         10 . The stent of  claim 1 , wherein the polymer of the coating has a glass transition temperature above 55 C.  
     
     
         11 . The stent of  claim 1  wherein the polymer of the coating has a glass transition temperature above 120 C.  
     
     
         12 . The stent of  claim 1 , wherein the polymeric coating comprise a polymer selected from the group consisting of polyacrylamides, polyethylene glycols, polyethylene oxide, vinyl alcohols, and poly(N-vinyl pyrrolidones.  
     
     
         13 . The stent of  claim 1 , wherein the polymeric coating additionally comprises polyamide.  
     
     
         14 . A biodegradable filament, the filament comprising: 
 an elongated, flexible member having a cross-section, and an outer surface; and,    a polymeric coating on said outer surface, said coating comprising a biodegradable or bioabsorbable polymer,    wherein, the polymeric coating has sufficient mechanical integrity to effectively maintain the flexible member in a substantially fixed configuration, until the coating has sufficiently been degraded or absorbed in vivo to effectively convert the structure back into a soft, elongated member.    
     
     
         15 . The stent of  claim 9  wherein the coating comprises a melt polymer.  
     
     
         16 . The stent of  claim 9 , wherein the coating comprises a solution polymer.  
     
     
         17 . The stent of  claim 9  wherein the filament comprises a surgical suture.  
     
     
         18 . The stent of  claim 12 , wherein the suture comprises a monofilament.  
     
     
         19 . The stent of  claim 12 , wherein the suture comprises a multifilament.  
     
     
         20 . The stent of  claim 12 , wherein the suture comprises a non-absorbable suture.  
     
     
         21 . The stent of  claim 12  wherein the suture comprises an absorbable suture.  
     
     
         22 . The stent of  claim 1 , wherein the coating comprises a polymer made from monomers selected from the group consisting of lactide, glycolide, para-dioxanone, caprolactone, and trimethylene carbonate, caprolactone, blends thereof and copolymers thereof  
     
     
         23 . The stent of  claim 1 , wherein the polymer of the coating has a glass transition temperature above 55 C.  
     
     
         24 . The stent of  claim 1  wherein the polymer of the coating has a glass transition temperature above 120 C.  
     
     
         25 . The stent of  claim 1 , wherein the polymeric coating comprise a polymer selected from the group consisting of polyacrylamides, polyethylene glycols, polyethylene oxide, vinyl alochols, and poly(N-vinyl pyrrolidones.  
     
     
         26 . The stent of  claim 1 , wherein the polymeric coating additionally comprises polyamide.  
     
     
         27 . A method of maintaining a passageway of a body lumen substantially open, comprising the steps of: 
 providing a stent, said stent comprising: 
 a helical structure having a plurality of coils, said structure having a longitudinal axis and a longitudinal passage, and said coils having a pitch, wherein said structure is made from a fiber, said fiber having a cross-section and said filament comprising: 
 an elongated flexible, filament member, having an external surface and a cross-section; and,  
 
 a, polymeric outer coating on the surface of the member, wherein, the polymeric coating has sufficient mechanical integrity to effectively maintain the flexible member in a helical configuration; and, 
 implanting said stent in a body lumen and maintaining the stent in the body lumen for a sufficient period of time to effectively maintain the passageway of the lumen substantially open for a desired period of time until the exterior coating softens, thereby converting the stent structure into a soft, flexible filamentary structure.