EXPANDABLE SHEATH

摘要

A delivery sheath includes an elastic outer tubular layer and an inner tubular layer having a thick wall portion integrally connected to a thin wall portion. The inner tubular layer can have a compressed or folded condition wherein the thin wall portion folds onto an outer surface of the thick wall portion under urging of the elastic outer tubular layer. When an implant passes therethrough, the outer tubular layer stretches and the inner tubular layer unfolds into an expanded lumen diameter. Once the implant passes, the outer tubular layer again urges the inner tubular layer into the compressed condition with the sheath reassuming its smaller profile. The sheath may also include selectively placed longitudinal rods that mediate friction between the inner and outer tubular layers to facilitate easy expansion and collapse, thereby reducing the push force needed to advance the implant through the sheath's lumen.

主权项

1. A sheath comprising:
an elastic outer tubular layer defining an initial elastic lumen extending axially therethrough, the initial elastic lumen having an initial diameter; and an inner tubular layer having a thick wall portion integrally connected to a thin wall portion, wherein the thick wall portion has a C-shaped cross section with a first longitudinally extending end and a second longitudinally extending end and wherein the thin wall portion extends between the first and second longitudinally extending ends so as to define an expanded lumen extending axially through the inner tubular layer, the expanded lumen having an expanded diameter larger than the initial diameter of the initial elastic lumen and; wherein the inner tubular layer, in a compressed condition, extends through the initial elastic lumen of the elastic outer tubular layer with the elastic outer tubular layer urging the first longitudinally extending end under the second longitudinally extending end of the inner tubular layer; and wherein the inner tubular layer, in a locally expanded condition, has the first and second longitudinally extending ends radially expanded apart, against the urging of the elastic outer tubular layer by passage of an implant, into a less overlapping condition with the thin wall portion extending therebetween to form the expanded lumen; and wherein the inner tubular layer is configured to be urged by the outer elastic tubular layer into the compressed condition after passage of the implant through the expanded lumen.