Abstract: A tool having a deployable cutting blade for making an undercut in a substrate is disclosed. The tool has a chamber positioned between its cutting tip and its tang. The cutting blade is movably mounted within the chamber. The blade is movable by sliding, pivoting or deflecting on a cantilever mounting and is movable between a retracted position within the chamber and an extended position projecting outwardly to engage and cut the substrate. Actuators for moving the blade include an eccentric cam mounted on a camshaft, a push rod and an inflatable balloon. Blades are also resiliently mounted and oriented so that their engagement with the substrate will cause them to retract into the chamber when the tool rotates in one direction and deploy into the extended position when the tool rotates in the opposite direction.

Abstract: A device positionable in an opening in a flexible membrane or in the lumen of a vessel having a flexible sidewall. The device distends or biases opposite portions defining the opening or forming the vessel sidewall outwardly in the plane of the device. The outward biasing draws opposing portions of the opening or sidewall inwardly in a direction perpendicular to the plane of the device and into apposition or contact.