COMPARISON OF NITROGLYCERINE, VERAPAMIL AND NIFEDIPINE IN THE MANAGEMENT OF ARTERIAL PRESSURE DURING CORONARY ARTERY SURGERY

The efficacy of nitroglycerine, verapamil and nifedipine incontrolling post-sternotomy hypertension was compared in fourgroups of 20 patients anaesthetized with fentanyl 100 µgkg^–1 undergoing elective coronary artery surgery. Vasodilatorswere started before surgery and adjusted to maintain systolicarterial pressure < 120% of pre-infusion values, the mean(±SEM) requirements being: nitroglycerine (group II)3.6±0.6 µg kg^–1 min^–1; verapamil groupIII) 31.1 ±2.6 µg kg^–1 min¹ nifedipine (groupIV) 1.7±0.2 µg kg^–1 min^–1 Systolicpressure decreased significantly by 5 min after starting infusionsin groups II and III. In the control group (I: no vasodilator)arterial pressure increased significantly following skin incisionand sternotomy. Pulmonary arterial and capillary wedge pressuresincreased significantly following sternotomy in groups I andIII. Heart rate increased after sternotomy in all groups, butonly reached significance in groups III and IV. There were nosignificant changes in cardiac index or vascular resistance,although the latter remained lower than pre-infusion valuesat all times in groups III and IV. The P-Q interval increasedsignificantly in group III. It is concluded that nifedipineis a suitable alternative to nitroglycerine for the controlof arterial pressure during coronary artery surgery, but verapamilis not recommended because of its negative inotropic effectand its depressant effect on A-V conduction.