Removable stent for body lumens
View Patent ↗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.
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, wherein the coating comprises a polymer selected from the group consisting of polyacrylamides, polyethylene glycols, polyethylene oxide, vinyl alcohols, poly(N-vinyl pyrrolidone)s and polymers made from monomers selected from the group consisting of lactide, glycolide, para-dioxanone, caprolactone, and trimethylene carbonate, caprolactone, blends thereof and copolymers thereof.
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. 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 polymer of the coating has a glass transition temperature above 55° C.
10. The stent of claim 1 wherein the polymer of the coating has a glass transition temperature above 120° C.
11. The stent of claim 1 wherein the polymeric coating additionally comprises polyamide.
12. 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, wherein the coating comprises a polymer selected from the group consisting of polyacrylamides, polyethylene glycols, polyethylene oxide, vinyl alcohols, poly(N-vinyl pyrrolidone)s and polymers made from monomers selected from the group consisting of lactide, glycolide, para-dioxanone, caprolactone, and trimethylene carbonate, caprolactone, blends thereof and copolymers thereof; 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.