The Effects Of Beating Heart With Mild Hypothermia On Myocardium Protection During Cardiopulmonary Bypass

Objective: To evaluate the effect of beating heart with mild hypothermia on the myocardium protection during cardiopulmonary bypass. Methods: In Part I, 40 patients were randomly divided into two groups: beating heart with mild hypothermia group (Group I, n=20) and cold cardioplegic arrest heart surgery group (Group II, n=20). In both groups, the duration of cardiopulmonary bypass, the lowest temperature of nasales pharynx, SBP, DBF, HR, CVP, T in 30 min, 1, 2, 4, 8, 12, 24, 48 h after operation, the time of respiratory support, drainage volume of pericardium and mediastinum were measured. In Part II, 20 patients were randomly divided into two groups: beating heart with mild hypothermia (Group I, n=12) and cold cardioplegic arrest heart surgery group(Group II, n=8). In Group I, the levels of LDH, CK, MDA, SOD and the activities of myocardiac Ca2+-ATPase and NOS were individually measured before CPB(T1), at 15 min after CPB(T2), at the end of CPB(T3) and 15 min after weaning from CPB(T4); In Group II, those parameters were asle measured before CPB(T1), after aortic clamp(T2), aortic clamp released (T3) and at 15 min after weaning from CPB(T4).Results: In Part I, the incidences of restoring spontaneous heart-beat, dopamine-required and defibrallation rate were obviously lower, the time of respiratory supportion was significantly shortened and drainage volume of pericardium and mediastium also markedly reduced after cardiac surgery in Group I than that in group II. In Part II, the levels of LDH, CK, MDA were lower in Group I than those in Group II at corresponding time. The activities of myocardiac Ca2+-ATPase and NOS were higher in Group I than those in Group II.Conclusions: Beating heart with mild hypothermia during open heart surgerycould reduce the serum activities of LDH and the CK and tevels of MDA, andincrease activities of serum SOD and myocardial Ca2+-ATPase and NOS, Itwas implied that the effective myocardial protection was obtained by beatingheart with mild hypothermia during cardiopulmonary bypass.