An improved delivery system for an implantable medical device includes a retention sheath for an implantable medical device. The retention sheath includes a central lumen extending from a proximal end to a distal end of the retention sheath, and a tapered portion disposed at a distal end of the retention sheath. The tapered portion of the retention sheath includes a first layer made of a low-friction material. The first layer may be movable from a compressed, folded configuration in an initial position, to a substantially uncompressed and unfolded configuration in a deployment position. The retention sheath also includes a second layer made of an expandable material. The second layer is disposed radially outward of and in contact with the first layer, and the second layer is configured to expand in a substantially radially outward direction when the first layer moves from the initial position to the deployment position.