Disclosed is a high-frequency intra-arterial cardiac support system having a balloon pump which may be positioned in a major artery downstream of a natural heart. The balloon pump comprises a pumping balloon of small displacement mounted upon and cyclically inflatable and deflatable by fluid flow through catheter having a lumen leading to the outside of the body. The balloon pump further comprises a valve mounted downstream of the pumping balloon. The system further comprises a control and drive mechanism for providing cyclical fluid flow to the lumen of the catheter for inflation and deflation of the pumping balloon. The cyclical flow and the cyclical inflation and deflation occur at a frequency which is at least three times the normal beating frequency of the natural heart. The small displacement of the pumping balloon is much smaller than the normal stroke volume of the natural heart.