Electrocardiographic changes after bilateral carotid sinus denervation in the rat.

The effect of bilateral carotid sinus denervation (CSD) on the ECG and on the monophasic ventricular action potential (MAP) was studied in 28 and 4 rats, respectively. After CSD, T wave changes, similar to those seen in man after carotid endarterectomy, were observed and mean Q-T prolongations of 19 ms were recorded (P less than 0.001). Mean MAP increased by 10 ms (P less than 0.02). P-QRS and heart rate remained stable. Propranolol, 10 mg/kg iv, before CSD and 10 mg.kg-1.day-1 iv for 2 days prevented all ECG abnormalities. Atropine, 1 mg/kg iv, before CSD and 2.5 mg.kg-1.day-1 iv for 2 days had no effect. Isoproterenol, 0.02-0.06 microgram iv, after CSD produced further lengthening of the MAP and Q-T interval. Blood gases and electrolytes remained unchanged, and cardiac histology was unremarkable. These results suggest that CSD produces alterations in cardiac sympathetic activity in the rat leading to MAP and Q-T prolongations and to changes in the T wave form. Similar mechanisms may be operative after carotid endarterectomy in man.