Magovern J A, Pae W E, Waldhausen J A
Department of Surgery, Milton S. Hershey Medical Center, Pennsylvania State University, Hershey, Pa.
J Thorac Cardiovasc Surg. 1988 Sep;96(3):408-13.
Low cardiac output in infants after cardiac operations continues to be a problem, yet little experimental work has been done to evaluate the various methods of protecting the immature myocardium. In this study, we have used an isolated working heart model to test three methods of myocardial protection in 3- to 4-week-old rabbit hearts: (1) topical cooling, (2) single-dose cardioplegia plus topical cooling, and (3) multiple-dose cardioplegia plus topical cooling. Myocardial temperature was maintained at 10 degrees C during ischemia, and St. Thomas' Hospital solution was used for cardioplegia. Sets of 18 hearts were subjected to 60, 90, or 120 minutes of ischemia, and within each set six hearts were protected by all three methods. After 90 and 120 minutes of ischemia, the percent recovery of aortic flow (expressed as mean +/- standard error of the mean) was lower in hearts protected with multiple-dose cardioplegia plus topical cooling (61.5% +/- 4.8%, 50.7% +/- 14.2%) than in those protected with topical cooling (92.4% +/- 5.7%, 94.3% +/- 12.8%) or single-dose cardioplegia plus topical cooling (86.4% +/- 5.3%, 90.2 +/- 3.6%). However, adenosine triphosphate, creatine phosphate, and glycogen levels were adequately preserved in all groups. Both topical cooling and single-dose cardioplegia provide effective protection for the immature rabbit heart during ischemia, but multiple-dose cardioplegia plus topical cooling results in inadequate preservation of hemodynamic function, despite adequate preservation of myocardial high-energy phosphate stores.
心脏手术后婴儿的心输出量低仍是一个问题，但为评估保护未成熟心肌的各种方法所做的实验工作很少。在本研究中，我们使用离体工作心脏模型，对3至4周龄兔心脏的三种心肌保护方法进行了测试：（1）局部降温；（2）单剂量心脏停搏液加局部降温；（3）多剂量心脏停搏液加局部降温。缺血期间心肌温度维持在10℃，并使用圣托马斯医院溶液作为心脏停搏液。每组18颗心脏分别经历60、90或120分钟的缺血，每组中有6颗心脏采用所有三种方法进行保护。在缺血90分钟和120分钟后，多剂量心脏停搏液加局部降温保护的心脏主动脉血流恢复百分比（以平均值±平均值标准误差表示）（61.5%±4.8%，50.7%±14.2%）低于局部降温保护的心脏（92.4%±5.7%，94.3%±12.8%）或单剂量心脏停搏液加局部降温保护的心脏（86.4%±5.3%，90.2±3.6%）。然而，所有组中的三磷酸腺苷、磷酸肌酸和糖原水平均得到充分保存。局部降温和单剂量心脏停搏液在缺血期间均能为未成熟兔心脏提供有效的保护，但多剂量心脏停搏液加局部降温尽管能充分保存心肌高能磷酸盐储备，但导致血流动力学功能保存不足。
