Abstract: A catheter apparatus for removing an obstruction within a body lumen includes an elongate tubular shaft defining a lumen and a flexible membrane that fluidly seals the distal end of the tubular shaft. At least one cutting element or tool is attached to and distally extends from the flexible membrane. An actuating mechanism is operatively connected to a proximal end of the tubular shaft. The actuating mechanism displaces a fluid disposed within the lumen of the tubular shaft in such a manner that the fluid oscillates the flexible membrane and the cutting element attached thereto. Accordingly, the catheter apparatus uses pulsatile fluid flow through the tubular shaft to transmit energy from the driving mechanical at the proximal end of the catheter apparatus to the flexible membrane at the distal end of the catheter apparatus. The transmitted energy causes the cutting element to oscillate and break up a target blood clot.