Morris C D, Budde J M, Velez D A, Muraki S, Zhao Z Q, Puskas J D, Guyton R A, Vinten-Johansen J
Division of Cardiothoracic Surgery, Emory University School of Medicine, Atlanta, Georgia, USA.
Ann Thorac Surg. 2001 Sep;72(3):679-87. doi: 10.1016/s0003-4975(01)02883-1.
Aortic cross-clamping is contraindicated in patients with severe atherosclerosis of the ascending aorta, and administration of chemical cardioplegia may be cumbersome in these patients. In this study, we demonstrate an alternative method of achieving cardioplegia by electrical stimulation of the vagus nerve.
In anesthetized canines, the left anterior descending coronary artery was reversibly ligated for 90 minutes, followed by cardiopulmonary bypass (CPB) and randomization to three groups (n = 8 each): (1) BCP group: 1 hour of intermittent hypothermic (4 degrees C) blood cardioplegia infusion; (2) CPB group: 1 hour of CPB alone; (3) EP group (group receiving electroplegia): 1 hour of intermittent vagal stimulation (total of 60 20-second electrical stimuli at 40 Hz, 6 to 10 V) with adjunctive pyridostigmine (0.5 mg/kg), verapamil (50 microg/kg), and propranolol (80 microg/kg) to potentiate hyperpolarization and suppress ectopic escape beats.
The EP group achieved consistent intervals of arrest with 3.8 +/- 1.2 escape beats per 20-second stimulation period. After 2 hours of reperfusion off CPB, the left anterior descending coronary artery segmental shortening was reduced from baseline in all groups, but the segmental shortening recovered to a greater extent in the EP group than in either the CPB or BCP group (2.4% +/- 1.4% versus -1.3% +/- 1.3% versus -4.0% +/- 0.8%, p < 0.05). Infarct size (TTC stain, percentage of area at risk) was comparable among groups (EP: 20.9% +/- 4.7%; CPB: 29.6% +/- 3.2%; BCP: 25.1% +/- 5.7%). Postischemic left anterior descending coronary artery endothelial function (percent maximum relaxation to acetylcholine) was depressed in the EP group (68.6% +/- 7.6% versus 102.3% +/- 6.4%, p < 0.05), but was comparable versus nonischemic circumflex function in the BCP group (77.1% +/- 11.9% versus 100.4% +/- 10.0%, p = 0.15) and the CPB group (93.8% +/- 6.6% versus 93.3% +/- 6.6%).
Electroplegia achieves elective intermittent cardiac arrest, avoids hypothermia, chemical cardioplegia, and aortic cross-clamping, with physiological outcomes comparable to blood cardioplegia.
升主动脉严重动脉粥样硬化的患者禁忌进行主动脉交叉钳夹，并且在这些患者中给予化学心脏停搏可能很麻烦。在本研究中，我们展示了一种通过电刺激迷走神经实现心脏停搏的替代方法。
在麻醉的犬中，可逆性结扎左前降支冠状动脉90分钟，然后进行体外循环（CPB）并随机分为三组（每组n = 8）：（1）BCP组：1小时间歇性低温（4℃）血液心脏停搏液输注；（2）CPB组：仅1小时CPB；（3）EP组（接受电心脏停搏的组）：1小时间歇性迷走神经刺激（共60次20秒的电刺激，频率40Hz，电压6至10V），并辅助使用吡啶斯的明（0.5mg/kg）、维拉帕米（50μg/kg）和普萘洛尔（80μg/kg）以增强超极化并抑制异位逸搏。
EP组实现了一致的停搏间期，每20秒刺激期有3.8±1.2次逸搏。在CPB外再灌注2小时后，所有组左前降支冠状动脉节段缩短均较基线降低，但EP组节段缩短的恢复程度大于CPB组或BCP组（2.4%±1.4%对-1.3%±1.3%对-4.0%±0.8%，p<0.05）。梗死面积（TTC染色，危险区域面积的百分比）在各组间相当（EP组：20.9%±4.7%；CPB组：29.6%±3.2%；BCP组：25.1%±5.7%）。缺血后左前降支冠状动脉内皮功能（对乙酰胆碱的最大舒张百分比）在EP组中降低（68.6%±7.6%对102.3%±6.4%，p<0.05），但与BCP组（77.1%±11.9%对100.4%±10.0%，p = 0.15）和CPB组（93.8%±6.6%对93.3%±6.6%）的非缺血性回旋支功能相当。
电心脏停搏可实现选择性间歇性心脏停搏，避免低温、化学心脏停搏和主动脉交叉钳夹，生理结果与血液心脏停搏相当。
