Experimental Studies On The Influence Of Hypothermic Continuously Electric-induced Ventricular Fibrillating During Cardiopulmonary Bypass On Myocardial Structure,Function And Energetic Metabolism

Experimental Studies on the Influence of Hypothermic Continuously Electric-induced Ventricular Fibrillating during Cardiopulmonary Bypass on Myocardial Structure,Function andEnergetic MetabolismAbstractMyocardial protective technologies, with the continuous experimental study and widespread clinical application, have undergone full development since Biglow et al first employed hypothermia in open-heart surgeries in 1950. Today, Hypothermic potissium arrest is the most widely used technology in the cardioprotective methods. But hypothermia fibrillating is still being used by some cardiac surgeons, especially in coronary artery bypass graft(CABG) surgery. A mount of clinic research had not found which was the better between them, the latter can also fit the needs of the surgery. Now, a large amount of clinic research has been done about the use of hypothermic fibrillating and affirmed its clinic result, but the research of compositive evaluation in the lab is few, and it is not full known the cardioprotection effect of the technology and it compared with classic arrest technology. So, we studied the influnce of hypothermic fibrillating and compared with cold crystalloid cardioplegia arrest in order to offer the objective experimental foundation for the clinic use of the technology.Base on the feline cardiopulmonary bypass(CPB) model, the changes of myocardial function, myocardial structure, energetic metaboliam and mitochondria Na+ 桲+ ATPase activity were observed to evaluate the cardioprotective effects of the two kinds of method of hypothermic electric-induced ventricular fibrillating and intermittent antegrade perfusion with cold crystalloid.CPB management63 felines.each weighted 3. 0 ?0. 5kg, were randomly divided into 3 groups with21 in each. Group I : Pure CPB without ACC. Group II: Base on CPB without ACC, continue induced fibrillating with 60Hz, 5V alternating current 90min at 30"C and reperfused 30min. Group III: After ACC at 30"C, 4'C crystalloid cardioplegia was perfused via aortic root; tropical hypothermia was obtained by pericardial ice mud application following arrest. Cold crystalloid myocardial protection solution was perfused via aortic root every 20-30min; at ACC 90min, aortic crossclamping was removed and reperrused 30 min.Results1. The changes of cardiac performancesLvsp and dp/dt max significant decreased after reperfused 30min in Group II and III and were significantly different from those in Group I . The most obviously decreasing was observed in them about dp/dt min and also significantly different from those in Group I . Lvedp values in Group I were the most significantly different from those in Group II and III and also sigiflcantly different between them.lt meaned that the cardiac performances of hypothermic fibrillating heart and cold crystalloid cardioplegia heart were damaged.2. Electromicroscopic observationsNo significant abnormality was spotted in Group I ,with nothing more than minimal swelling of the cells ang part of the mitochondrias. After 30min reprfusion, hypothermic fibrillating heart showed ischemic and hypoxic injuries at myocardial ultrastruture. Cell edema, mitochondria swelling or crista fracture or even cavitation and capillary endothelium swelling et al was observed in the group II. There was no significantly different between hypothermic fibrillating and cold crystalloid cardioplegia arrest.3. The changes of myocardial oxygen consumption( MVO2)The research of oxygen supply and demand in different myocardial protection technique is an important route to evaluate them. We built the model to measure MVO2. The data suggested that: (1) MV02 significantly decreased during hypothermicfibrillating in Group II compared with beating heart in Group I . (2) MVO2 was slightly lower than that of beating heart at the same temperature(30'C). (3) In Group II and III, MVO2 was obviously increased compared with Group I at reperfusion 30min.4. The changes of myocardial energetic metabolism(1) The changes of coronary sinu...