| Background and Objective The heart arrest and myocardial protection of young infants is always the focus problem during the open heart operation. The study of myocardial protection is a key point for improving the development of cardiac surgery. Hypothermia and medium cardioplegia have been regarded as two elementary factors in myocardial protection and been used for a long time. However, with the rapid developments of basic study in ultrastructure of myocardium cell and and the technique of cardiac surgery, the shortages of cold crystalloid cardioplegia have been gradually recognized, especially for the immaturity myocardium who suffered from weak heart function, severe condition and cyanosis. Nowdays, cold crystalloid cardioplegia, cold or warm blood cardioplegia are still used in open heart operation in different degree. But the merits and shortages of them are apparent. Since there are differences in the structure of the myocardium, metabolism, and the tolerance to hypoxia between the adults and neonate, the methods of myocardial protection for the adult are not suitable for the neonate. It is the point to search for the best method of myocardial protection. What is the excellent method of myocardial protection in heart short ischemic duration is the problem generally focused by the scholars all over the world. According to " integrated myocardial protection" method put forward by Buckberg recently, We want to compare several methods by clinical research, evaluate the " integrated myocardial protection" method and probe the mechanism ofmyocardium impairment in order to offer the theoretical foundation and practical experiences for avoiding myocardial impairment.Methods The present paper has shown the effects of myocardial protection of 30 patients with congenital heart disease. The patient were divided into 3 groups randomly according to different kinds of cardioplegia infused during corrective operation. Cardiac troponinT(cTn-T),endothelin-l(ET-l),atrial natriuretic peptide(ANP) were measured, myocardial ultrastructure, and clinical observations were observed to evaluate the effect of" integrated myocardial protection" method.Results During the experiment, it was found the peak values of cTn-T was the highest in CC group which was 1.13 times of that in CBC group, 1. 67 times of that in ICBC group. CTn-T peak values appeared earlier and existed shorter-time than it did in the other 2 groups. The number of patients with cTn-T values above 0.5ug/L was less in ICBC group compared to the other 2 groups. ET-1 values was the highest in CC group, and the lowest in ICBC group. The higher ET-1 levels existed continuously till 72h after removal of aortic crossclamp in CC group, in contrast to it lowered down to normal levels at 48h after removal of aortic crossclamp in ICBC group, and it happened at 72h after removal aortic crossclamp in CBC group. A rapid increase of ANP during CPB was seen in ICBC group, however, the similar increase was seen only after removal aortic crossclamp in the other 2 groups. By means of pathologic and ultrastructural observations various degrees of ischemic injury were found in all groups, especially more serious in CC group. The time of vascular active drugs application was the shortest in ICBC group, which was 2.8 days, versus CBC group, 3.0 days (p>0.05), versus CC group, 3.6 days (p<0.05).Conclusions The study demonstrate that ICBC had a better myocardial protection effect than CBC and CC did during heart arrest for 30-50 min. This ideal protection is due to that ICBC controls injury of global ischemia and absence of oxygen, reperfusion injury, and remain normal tissue structure during ischemia. Ordinary pathologic studies cannot precisely show the reversible injuries of myocardial cells, however, electroscopic studies of the uhrastructures of myocardium may reflect the much earlier stage of myocardium ischemic and hypoxic injuries, and manifest the satisfactory myocardium effect of the ICBC. The patients recovered good cardiac function rapidly who reached perfusion with...
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