The invention provides devices and methods for thoracoscopically arresting the heart and establishing cardiopulmonary bypass, thus facilitating a variety of less-invasive surgical procedures on and within the heart and great vessels of the thorax. In one embodiment, the invention provides a thoracoscopic system for arresting a patient's heart including a clamp configured for introduction into the patient's thoracic cavity through a percutaneous intercostal penetration in the patient's chest. The clamp is positionable about the patient's ascending aorta between the coronary arteries and the brachiocephalic artery. The clamp is coupled to the distal end of an elongated handle means for manipulating the clamp from a location outside of the patient's thoracic cavity. A means for actuating the clamp is coupled to the proximal end of the handle means. When actuated, the clamp blocks blood flow through the ascending aorta. A delivery cannula may be used to deliver cardioplegic fluid into the ascending aorta upstream from the clamp to arrest cardiac function.