Embodiments of the invention provide for a unidirectional flow valve. For example, embodiments of the invention include a method of providing a unidirectional flow valve to a vein that include folding a first portion of a vein over an adjacent second portion of a vein and engaging at least two opposing...http://www.google.es/patents/US20040215339?utm_source=gb-gplus-sharePatente US20040215339 - Venous valve apparatus and method
