A device comprising a reference ring that may be temporarily disposed in abutment with the inferior perimeter surface of a heart valve to aid non-optical visualization of the valve annulus. The reference ring is elastically transformable between a straight delivery configuration and a generally circular...http://www.google.de/patents/US20060195134?utm_source=gb-gplus-sharePatent US20060195134 - Device, system, and method for aiding valve annuloplasty
