Single aortic clamping for proximal and distal anastomoses in coronary operations: study of myocardial temperatures in nonvented hearts.

A prospective analysis of myocardial temperatures (septum, left and right atria, and right ventricle) in coronary operations was carried out in nonvented human hearts during a single period of aortic cross-clamping for construction of all anastomoses, proximal and distal. Also a comparison was made of normothermic versus hypothermic perfusion during cardiopulmonary bypass (CPB). Results indicate that (1) immediately after cross-clampling and infusion of the cardioplegic solution, the septal temperature was identical for hypothermic and normothermic perfusion; (2) at 20 minutes of clamping, however, hypothermic patients had lower septal temperatures than normothermic patients; and (3) at the end of the cross-clamping period, the septal temperature was lower in hypothermic hearts. The left and right atrial and right ventricular temperatures were lower throughout CPB in patients with hypothermic perfusion. It is concluded that if a single period of aortic cross-clamping under cardioplegic arrest is to be used for construction of all anastomoses in nonvented hearts during a coronary operation, core hypothermia is necessary and should be maintained until the aorta is unclamped. The surgeon cannot rely on cold slush and cardioplegia alone to cool the heart while the proximal anastomoses are being performed, since blood from the bronchial (left atrium) and systemic (right atrium) circulations warms the heart.