A medical device (30) which is structured and arranged to be inserted into a body vessel in a temporary delivery shape and to subsequently change shape therein, the device is structured and arranged to change shape via an expanded delivered shape to a further expanded shape to extend outside the perimeter or orifice of an outer wall of the vessel by tissue cutting action exerted by said device through the shape change on the vessel from the interior thereof, the device having a cross-section, and during the change of shape the cross-section is adapted to expand such that the device circumferentially cut the vessel.
