常温体外循环心脏缓慢空跳状态下心肌保护效果的实验研究

Myocardial protective effects on empty-beating heart with normothemic cardiopulmonary bypass: a experimental study

目的 评价常温体外循环心脏缓慢空跳术式对心肌保护效果的影响。方法 杂种犬 12只 ,随机分为停跳组和空跳组。两组均常规建立体外循环。停跳组阻断升主动脉 ,心脏灌注冷晶体停跳液 ;空跳组不阻断升主动脉 ,以一定的灌注压力和流量维持心脏空跳。分别于停跳 (开机 )前、停跳 (空跳 ) 90min、复跳 (撤机 ) 30min ,抽冠状窦血行有关生化检测、取右心室心肌行病理组织检查。结果 停跳组在刚复跳及复跳 30min其冠状窦血中丙二醛 (malondialdehyde ,MDA)及乳酸脱氢酶同工酶 (lacticaiddehydrogenase,LDH1)值均显著高于停跳前 (P <0 0 5 ) ,并显著高于空跳组撤机 30min时的MDA及LDH1值 (P <0 0 5 ) ;而空跳组在研究时段12 0min内其心脏冠状窦血MDA及LDH1值均无显著性差异(P >0 0 5 )。在心肌超微结构改变方面 :停跳组在停跳 90min及复跳 30min ,均出现较严重心肌损伤的改变 ,而空跳组同样时段仅出现轻度可逆性改变。结论 体外循环下空跳法在减少心肌损害 ,避免缺血再灌注损伤方面优于停跳法。

Objectives To investigate the effects of the operation on empty beating heart with normothemic cardiopulmonary bypass (CPB) on myocardial protection. Methods Twelve dogs were divided randomly into two groups: Empty beating heart group and heart arrested group. All placed on CPB and at 34℃. Heart arrested group, aortic cross clamping, with crystalline cardioplegia trograte (10 mL·kg·min), Arrested for 90 min, then realeased cross clamping, and recovered the heart beating 30 min; empty beating heart group, no aortic cross clamping, CPB with high flow and maintain the mean aortic pressure at 40～60 mmHg, beating for 90 min, then stopped CPB and maintain beating 30 min. During the experiments the electrocardiogram was recorded; in different phrase (Before heart arrested or empty beating, heart arrested or beating 90 min, recovered or off CPB 30 min ), the blood sample of coronary sinus were taken to measure the biochemical indication including malondialdehyde (MDA) and lactic aid dehydrogenase (LDH 1).Myocardial specimens were observed by electron micro scope. Results MDA in coronary sinus blood: In heart arrested group at 0 min and 30 min after recovering, MDA were higher than that before arrested ( P <0 05); MDA in heart arrested group at 0 min and 30 min after recovering were higher than that in empty beating heart group at 0 min and 30 min after off CPB ( P <0 05). LDH 1 in coronary sinus blood: In heart arrested group at 0 min and 30 min after recovering, LDH 1 were higher than that before arrested ( P <0 05), and LDH 1 in heart arrested group at 30 min after recovering was also higher than that in empty beating heart group at 30 min after off CPB ( P <0 05). There was no significant difference in empty beating heart group. On ultrastructure observation: Mild and reversible ultrastructural changes were found in all the two groups at 90 min. But in heart arrested group, there was the edging aggregation of nuclear chromation, fomation of petty coagula and pyknosis of nuclear; At 30 min after recovering, heart arrested group has edging aggregation of chromation, vascular degeneration, some intercalated disk deavaging, and myomeres intact. At 30 min after off CPB in empty beating heart group, the changes were mild and unobvious. Conclusions Empty beating heart method had more advantages than arrested heart method in the aspect of reducing myocardial damages , and avoiding the ischemic reperfusion damages.