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Abstract
Cardioplegic solutions contain a variety of chemical agents that are designed to arrest the heart rapidly in diastole, create a quiescent operating field, and provide reliable protection against ischemia/reperfusion injury. Potassium is the most common agent used for chemical cardioplegia. Because the heart is an obligate aerobic organ, it is dependent upon a continuous supply of oxygen to maintain normal function. Myocardial oxygen reserve is exhausted within 8 seconds following the onset of normothermic global ischemia. The ability of the heart to resume normal electromechanical function adequate to support the systemic circulation must rapidly follow the ischemic interval. Most investigators agree that the basic principles for adequate myocardial protection include: 1) rapid induction of arrest, 2) mild or moderate hypothermia, 3) avoidance of substrate depletion and 4) attention to intracellular edema. The need for inotropic support or mechanical support devices, to wean the patient from cardiopulmonary bypass represents a failure of myocardial protection