Abstract: A multi-lumen laser enhanced transluminal angioplasy catheter apparatus provided with a balloon or expandable member which is coupled to a catheter connecting manifold member providing a plurality of inlet ports for handling and delivering procedure-dependent materials. A laser fiber advance unit, in turn, controllably advances and couples the lasing fiber between the catheter manifold and a laser control unit. The fiber advance unit provides interlock means preventing actuation or operation of the control unit, unless and until the tip of the laser beam transmitting fiber extends beyond the distal end of the catheter, and means are provided for controlling the insertion extent of advancement of the laser fiber and its transmitting tip into the body of the catheter.