Hemodynamic effects of esmolol in chronically beta-blocked patients undergoing aortocoronary bypass surgery

The hemodynamic effects of esmolol were studied in 40 patients scheduled for elective coronary artery surgery to determine whether the administration of esmolol in chronically beta-blocked patients would result in additional attenuation of sympathetically mediated hemodynamic stress responses to noxious stimuli. Patients were randomly assigned to receive IV infusions of esmolol or 5% dextrose in water (D5W). All received their regular dose of beta-adrenergic blocker within 6 hr of surgery and were anesthetized with diazepam, pancuronium, and enflurane. Increases (greater than 25% above baseline) in systolic blood pressure were treated with sodium nitroprusside (SNP). Esmolol was started before induction of anesthesia and continued until 5 min after maximal sternal spread. There were no statistically significant differences between the esmolol and control groups in any hemodynamic parameter during induction, intubation, skin incision, and sternotomy. Only at 5 min after maximal sternal spread was there a statistically significant lower systolic blood pressure in the esmolol-treated group. However the incidence and magnitude of SNP use in the control group was significantly (P less than 0.05) greater. Thus, the lower blood pressure, in the absence of changes in systemic vascular resistance, cardiac index, heart rate, and pulmonary capillary wedge pressure points toward a decrease in myocardial contractility, suggesting that the addition of esmolol to chronically used beta-blockers resulted in an additional negative inotropic effect. We conclude that in patients with coronary artery disease in whom chronic beta-blocker therapy is continued until the time of surgery, esmolol does not further attenuate the heart rate response but does attenuate the increase in blood pressure.(ABSTRACT TRUNCATED AT 250 WORDS)