Percutaneous methods and apparatus for forming a venous valve from autologous tissue by creating at least one subintimal longitudinal dissection that forms at least one flap of intimal tissue are disclosed. In one method, a balloon catheter having a dissecting blade mounted thereon is delivered to a target site where a new venous valve is to be created. The balloon is inflated to deploy the blade against the vein wall, and the catheter is longitudinally translated such that the blade dissects a subintimal layer of the vein wall. The balloon is subsequently deflated such that the blade pulls a flap of the dissected tissue towards the vein lumen, thereby creating a leaflet and corresponding pocket/sinus in the vein that collectively act as a monocuspid venous valve. Methods of forming new bicuspid and tricuspid venous valves utilizing two or three dissecting blades mounted on the balloon are also disclosed.
