A comparison of esmolol & diltiazem for heart rate control during coronary revascularisation on beating heart.

ABSTRACT

This prospective study was done to compare the control of heart rate and haemodynamics during coronary artery revascularisation without cardiopulmonary bypass using either esmolol or diltiazem. Sixty adult patients with one or two vessel coronary artery disease, were randomly divided into 2 equal groups. Group A received a 500 micrograms/kg loading dose of esmolol followed by a 100 micrograms/kg/h infusion, for control of heart rate during surgical anastomosis of the coronary vessel. While Group B received 0.15 mg/kg diltiazem as a loading dose followed by a 5 mg/h infusion for heart rate control, during the anastomosis. It was seen that heart rate control was better in Group A, 51.4 (+/- 1.3) beats/min, than in Group B, 69.6 (+/- 3.9) beats/min but the decrease in heart rate was significant in both the groups at peak effect compared to respective predrug values. Group A patients had unchanged systemic resistance and pulmonary artery wedge pressure but mean pulmonary artery pressure and pulmonary vascular resistance were significantly raised. Group B patients had decreased systemic resistance, mean pulmonary artery pressure and pulmonary artery wedge pressure, and reduced right ventricular stroke work index. We concluded that although esmolol provided dramatically slower heart rates, during surgery, the resulting elevations in mean pulmonary artery pressure and pulmonary vascular resistance would require caution if used in patients with underlying right ventricular dysfunction from ischaemia or infarction. Diltiazem by virtue of its effects on systemic vascular resistance, cardiac output, and lowering of mean arterial pressure may be a better choice in hypertensive patients.