In a valvulotome, when an operating wire is advanced or withdrawn, a pair of arms project from or sink into a sheath, and cutters at the tips or the arms open or close. When the arms are stowed in the sheath, forces causing the two cutters to join change directions sequentially with three pairs of bents...http://www.google.de/patents/US5624455?utm_source=gb-gplus-sharePatent US5624455 - Freely projectable/sinkable valvulotome and freely projectable/sinkable venous valve valvulotome
