An apparatus for controlling fluid flow within a host body has a first shell and a second shell for coupling with the second shell to form a cylindrical object suitable for engaging and surrounding a selected canal with the host body. The cylindrical object is open at both ends and has an interior diameter...http://www.google.de/patents/US6319191?utm_source=gb-gplus-sharePatent US6319191 - Implantable body fluid flow control device
