Topical hypothermic protection of the myocardium.

Profound topical hypothermia for intraoperative protection of the heart has been employed as an alternative to selective coronary perfusion with excellent clinical results. Based upon observations that hypothermia decreases cellular metabolism and prevents cellular damage from anoxia, topical hypothermia has been employed to provide protection for anoxic intervals exceeding 60 minutes. Additional advantages of this technique include a bloodless operative field with a flaccid myocardium. A continuous infusion of saline at 4 degrees C provides a simple and effective method of creating myocardial hypothermia. While topical hypothermia has been used successfully with anoxic intervals of 120 minutes, recent evidence indicates that in patients with combined coronary disease and ventricular hypertrophy, the degree of protection is inadequate after 70 minutes. Further investigation is needed to define more completely the degree and length of protection and to identify those situations in which the protection becomes inadequate.