A prosthetic valve is provided for implantation in a stenosed aortic valve. The prosthetic valve includes a radially collapsible frame configured for advancement through a patients vasculature using a catheterization technique. A collapsible valvular structure is sewn to the frame for permitting blood to flow in only one direction. An internal cover extends along an internal surface of the frame. The internal cover forms a tubular sleeve positioned between a lower extremity of the frame and the valvular structure. The internal cover prevents the passage of blood through spaces between bars of the frame. An upper end of the internal cover is sutured to the valvular structure. The internal cover is preferably made of pericardium.
