Electroplegia: An alternative to blood cardioplegia for arresting the heart during conventional (on-pump) cardiac operation

Background. Aortic cross-clamping is contraindicated in patients with sever e atherosclerosis of the ascending aorta, and administration of chemical ca rdioplegia may be cumbersome in these patients. In this study, we demonstra te an alternative method of achieving cardioplegia by electrical stimulatio n of the vagus nerve. Methods. In anesthetized canines, the left anterior descending coronary art ery was reversibly ligated for 90 minutes, followed by cardiopulmonary bypa ss (CPB) and randomization to three groups (n = 8 each): (1) BCP group: 1 h our of intermittent hypothermic WO blood cardioplegia infusion; (2) CPB gro up: I hour of CPB alone; (3) EP group (group receiving electroplegia): 1 ho ur of intermittent vagal stimulation (total of 60 20-second electrical stim uli at 40 Hz, 6 to 10 V) with adjunctive pyridostigmine (0.5 mg/kg), verapa mil (50 mug/kg), and propranolol (80 mug/kg) to potentiate hyperpolarizatio n and suppress ectopic escape beats. Results. The EP group achieved consistent intervals of arrest with 3.8 +/- 1.2 escape beats per 20-second stimulation period. After 2 hours of reperfu sion off CPB, the left anterior descending coronary artery segmental shorte ning 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 amon g groups (EP: 20.9% +/- 4.7%; CPB: 29.6% +/- 3.2%; BCP: 25.1% +/- 5.7%). Po stischemic left anterior descending coronary artery endothelial function (p ercent 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% <plus/minus> 11.9% versus 100.4% +/- 10.0%, p = 0.15) and the CPB group (93.8% +/- 6.6% versu s 93.3% 6.6%). Conclusions. Electroplegia achieves elective intermittent cardiac arrest, a voids hypothermia, chemical cardioplegia, and aortic cross-clamping, with p hysiological outcomes comparable to blood cardioplegia. (C) 2001 by The Soc iety of Thoracic Surgeons.