Hemodynamic and angiographic comparison of intravenous nitroglycerin and nicardipine mainly in subjects without coronary artery disease.

Twenty patients were studied during cardiac catheterization to compare hemodynamic and quantitative angiographic effects of intravenous nicardipine and nitroglycerin. After baseline measurements, nicardipine or nitroglycerin was administered by randomized continuous infusion beginning at 10 micrograms/min titrated to achieve a 10 to 12% reduction in systemic arterial pressure. Hemodynamic measurements and angiography were then repeated. Nicardipine did not change heart rate, and a small decrease (82 +/- 4 vs 75 +/- 4 beats/min) was observed with nitroglycerin, whereas mean arterial pressure decreased similarly (-11%) in both groups. Nicardipine increased (+13%) and nitroglycerin decreased (-21%) cardiac output. Although both drugs were associated with significant reductions in pulmonary artery wedge and pulmonary artery pressures, changes were greater with nitroglycerin for pulmonary artery wedge (-49% vs -26%) and pulmonary artery (-39% vs -13%) pressures, whereas only nitroglycerin reduced right atrial pressure significantly. Neither drug altered left ventricular ejection fraction or pulmonary vascular resistance, and only nicardipine decreased systemic vascular resistance significantly. Quantitative coronary angiography (videodensitometry) showed dilation of the left main, proximal, mid and distal anterior descending and circumflex segments by both nitroglycerin and nicardipine. Nicardipine dilated small (< 2 mm2) and large (> 2) arterial segments equally, whereas nitroglycerin showed a proportionately greater effect on small vessels.