Self-indexing coupling for rotational angioplasty device

A rotational angioplasty device comprising:

• a handle housing;
• a rotatable prime mover carried by a prime mover carriage which is disposed within the handle housing, the prime mover carriage being longitudinally movable with respect to the handle housing;
• an exchangeable drive shaft cartridge removably attachable to the handle housing further comprising:
• a tubular core element mounted within the cartridge;
• a longitudinally movable tube disposed within the tubular element and having a proximal end portion which is removably attachable to the prime mover carriage for longitudinal movement therewith;
• a rotatable flexible drive shaft having a proximal portion which is disposed within the longitudinally movable tube and a distal portion which includes a tissue removal implement, said proximal portion having a shank at its proximal end;
• a drive shaft attachment mechanism removably attaching the shank of the drive shaft to the prime mover;
• and
• a coupling for connecting said moveable tube with said prime mover carriage and adjusting the relative position of said moveable tube and said proximal portion of said drive shaft, said coupling further comprising:
• a prime mover carriage coupling element fixed to said prime mover carriage having a first surface forming one part of a coupling interface;
• a second surface forming a second part of said coupling interface constructed on said moveable tube, said first and second coupling surfaces overlapping in a telescoping manner to form the coupling interface;
• a retention groove constructed in one of said first and second coupling surfaces in said interface;
• an index groove constructed in one of said first and second coupling surfaces in said interface;
• an annular resilient element positioned in said retention groove and exerting a radial force between said first and second coupling surfaces;
• said resilient element expanding into said index groove when said retention and index grooves are aligned;
• wherein, in said aligned relation, the moveable tube and said proximal portion of said drive shaft are relatively positioned to allow rotation of said drive shaft within said moveable tube.