Plasma and atrial propranolol after preoperative withdrawal.

Of 34 patients scheduled for aortocoronary bypass operations who were withdrawn from chronic propranolol therapy between 18 and 48 hours before anesthesia and operation, propranolol was detected in the plasma of nine and in atrial tissue of five patients. Higher plasma levels were associated with higher propranolol intake and with shorter time of withdrawal. In 15 patients withdrawn preoperatively from propranolol the heart rate and blood pressure response to 3 mug isoproterenol was not significantly different from the response of similar patients who had received no propranolol. In contrast to the response of healthy subjects, most patients with coronary artery disease responded to isoproterenol with a decrease in systolic blood pressure. Plasma propranolol levels after a 0.5 mg bolus given intravenously during operation produced a peak level of 40 ng/ml in one minute and disappeared in five minutes. These studies suggest that no beta blockade persists 18 hours after acute preoperative withdrawal of propranolol in patients taking up to 300 mg per day for control of angina. In view of the reported hazards of abrupt withdrawal of propranolol before operation and the reported usefulness of propranolol in treating tachyarrhythmias during operation, we suggest that early preoperative withdrawal of propranolol may be more hazardous than its continuation before coronary bypass operations.