Rolling membrane stent delivery device

Abstract

A device for deploying radially self-expanded stents and other radially expandable stents includes an inner catheter, an outer catheter surrounding the inner catheter, and a tubular stent retaining sheath formed of a rolling membrane. The sheath is doubled over upon itself to provide an inner sheath layer attached to the inner catheter, and an outer sheath layer attached to the outer catheter. The sheath layers extend along and surround a radially self-expanding stent, to maintain the stent distally of the inner catheter and in a radially compressed, axially elongated state. Distally of the stent, the inner and outer sheath layers converge and are narrowed in the distal direction to define a tapered distal tip. To release the stent, the outer catheter is moved proximally to roll the membrane away from its surrounding relation to the stent, whereupon the stent radially self-expands progressively, beginning at its distal end. When completely retracted after stent release, the sheath surrounds a distal region of the inner catheter, and can provide a protective layer between arterial tissue and a dilatation balloon supported along the distal region. As an alternative, a stent formed of a recovery metal can be plastically deformed into a reduced radius state for delivery, which facilitates use of a more flexible stent retaining sheath. A further alternative involves securing the sheath proximally of the dilatation balloon, so that sheath retraction leaves the dilatation balloon exposed, rather than covered by the sheath.