The invention provides an expandable double-walled sleeve whose space between the walls is filled with curable material and which is designed for the local support and/or reinforcement of a body vessel, absorbent material being provided between its walls which are fabricated from an essentially non-extensible material. This achieves the advantage that the curable material remains uniformly distributed between the walls of the sleeve even if the sleeve is rolled around a still unexpanded PTA balloon in order to be brought to the desired position by means of said balloon.