Vagus nerve stimulation as a method to temporarily slow or arrest the heart

Background. Electrical stimulation of nerves is used to study nervous system and body function relationships. Electrical stimulation of the vagus nerve was used to slow the heart during coronary artery bypass grafting. Methods. A 48-year-old man with multivessel coronary artery disease, scheduled for revascularization, gave informed consent for the surgeon to stimulate his vagus nerve. As part of the operation the left internal mammary artery was harvested as a pedicle and the patient was placed on cardiopulmonary bypass. The vagus nerve was isolated as it crossed the aorta just lateral to the phrenic nerve. Pacing wires were placed (1 cm apart) allowing prodromic conduction. With the patient fully supported by cardiopulmonary bypass and after administration of neostigmine (2.5 mg intravenously) eight separate continuous 5-second electrical pulse trains (25 Hz, 20 V, pulse width of 0.1 ms) were delivered to the nerve with 30-second rest periods between each stimulation. During the periods of stimulation the mammary artery to left anterior descending artery anastomosis was completed. Results. Electrical stimulation caused cessation of the heartbeat, termination of the same resulted in normal sinus rhythm, although it was slowed by the neostigmine. Suturing of the anastomosis was done during periods of stimulation. Additional anastomoses were completed using cardiopulmonary bypass-delivered cardioplegia and aortic cross-clamping. Conclusions. Electrical stimulation of the vagus nerve slowed and temporarily arrested the heart for brief periods to allow critical placement of anastomotic sutures.