The invention provides a system and method for performing less-invasive surgical procedures within a body cavity. In a preferred embodiment, the invention provides a system and method for temporarily occluding a blood vessel in an arterial graft in a thoracoscopic coronary artery bypass grafting procedure. The system comprises a clamp (2) and an introducer (1) for introducing the clamp through a percutaneous penetration into the body cavity and applying the clamp to a tissue structure such as a blood vessel. The clamp has a pair of movable jaws (65, 67) coupled to one another, each jaw having a distal portion for engaging the tissue structure and a proximal portion having a camming surface (66, 68). The introducer has a longitudinal shaft (3) with a clamp engaging member (25) slidably coupled to the distal end of the shaft for releasably holding the clamp. A handle (11) is coupled to the proximal end of the shaft. The handle can be manipulated to axially slide the shaft with respect to the clamp engaging member so that the shaft engages the camming surfaces of the clamp to open and close the distal portions of the jaws without releasing the clamp from the introducer.