The majority of cardiac surgical procedures are accomplished using cardioplegia-induced cardiac arrest with cardiopulmonary bypass (CPB) to maintain perfusion to other organs. However, in certain situations, the nature of the surgical procedure or the pathology of the underlying condition necessitates complete cessation of blood flow. For example, safe removal of large tumors encroaching on vascular structures requires provision of a bloodless field to enable dissection, or operations on the aorta itself may preclude application of a cross-clamp because of the pathological anatomy. Preservation of organ function during the period of total circulatory arrest can be aided by reducing the core temperature of the body. The technique of core cooling combined with cessation of blood flow is termed “deep hypothermic circulatory arrest” (DHCA). DHCA provides excellent operating conditions – albeit of limited duration – whilst ameliorating the major adverse consequences of organ ischemia. During DHCA the brain is the organ most vulnerable to injury, but may be protected if cooled to reduce its metabolic activity, and hence oxygen requirements, before and during the period of arrest. Similarly, preservation of the function of other organs less susceptible to ischemic damage may be afforded by core cooling. DHCA owes its existence to two overlapping eras; a brief period in the early 1950s when hypothermia was used as the sole method for organ protection during surgery and the current epoch of CPB heralded by Gibbon in 1953.
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