Trimetaphan may cause coronary artery spasm

We describe a patient in whom possible coronary artery spasm occurred during the infusion of trimetaphan. A 55-year-old man with a meningioma was scheduled for surgical excision of the tumour. He denied any previous history of chest pain. Anaesthesia was maintained with nitrous oxide (67%) in oxygen. The blood pressure before commencement of the surgery was 114/70 mmHg, and the pulse rate was 60 beats min-1. The blood pressure rose to 152/94 mmHg (the pulse rate to 62 beats min-1) during incision of the scalp, and intravenous infusion of trimetaphan was initiated. The blood pressure gradually decreased to 113/58 mmHg (the pulse rate 64 beats min-1) 10 min after start of this infusion, and premature ventricular contractions were evident on the electrocardiogram. Trimetaphan was withheld, and lignocaine was given intravenously. The premature ventricular contractions disappeared but ST segments were elevated. Glyceryl trinitrate was then infused intravenously. The ST segments remained elevated for 5 min, were depressed for 2 min and finally became isoelectric. There were no wide swings in blood pressure or pulse rate during the event. Post-operative laboratory examination revealed no evidence of myocardial infarction. Recovery of the patient was uneventful.