Hypertension following coronary artery bypass graft surgery: comparison of hemodynamic responses to nitroprusside, phentolamine, and converting enzyme inhibitor.

Sustained systemic hypertension (mean arterial pressure 119 +/- 4 mm Hg) developed in 39 patients undergoing coronary artery bypass graft (CABG) surgery. In groups of patients with comparable mean arterial pressure, left ventricular filling pressure, heart rate, and cardiac output, treatment with sodium nitroprusside (NP) in 20 patients, phentolamine (PH) in 10 patients and nonapeptide converting enzyme inhibitor (CEI) in nine patients uniformly lowered mean arterial pressure by 26, 21, and 20%, respectively. Cardiac output increased during NP (5.7 +/- 0.1 to 6.4 +/- 0.3 L/min, P < 0.0005) and after CEI (5.7 +/- 0.4 to 7.4 +/- 0.5 L/min, P < 0.0005) but not after PH (5.7 +/- 0.3 to 5.9 +/- 0.3 L/min, P > 0.05). Left ventricular filling pressure decreased in all groups (P < 0.005), but heart rate increased during NP (91.3 +/- 2.4 to 98.4 +/- 2.2 beats/min, P < 0.0005 and after PH (95.5 +/- 2.1 to 99.2 +/- 3.0, P < 0.005), while it was unchanged after CEI P > 0.05). Of the nine patients with CABG hypertension who received CEI, seven exhibited a mean decrease in arterial pressure of 18.5 +/- 3.4%, while in the remaining two patients, mean arterial pressure was decreased only 3.4%. In the former, the pretreatment mean plasma renin activity (PRA) was 7.5 +/- 2.4 ng/ml/hr, while in the latter, mean PRA was 1.3 ng/ml/hr.