COMPARATIVE EFFECTS OF VOLUME LOADING, DOBUTAMINE, AND NITROPRUSSIDE IN PATIENTS WITH PREDOMINANT RIGHT VENTRICULAR INFARCTION

To assess the value of volume loading and to determine the relative efficacy of dobutamine compared with nitroprusside therapy in acute right ventricular infarction (RVMI), 13 patients with clinical, hemodynamic, and radionuclide angiographic evidence of RVMI were evaluated. In 10 patients who had an initial pulmonary arterial wedge pressure less than 18 mm Hg, volume loading did not improve cardiac index (1.9 .+-. 0.5 [SD] to 2.1 .+-. 0.4 liters/min/m2), despite significant increases in mean right atrial pressure (11 .+-. 2 to 15 .+-. 2 mm Hg, p < .001) and pulmonary arterial wedge pressure (10 .+-. 4 to 15 .+-. 2 mm Hg, p < .001). Nine patients recieved dobutamine or nitroprusside in random order, while hemodynamic measurements and radionuclide angiograms were obtained simultaneously. Compared with nitroprusside, dobutamine produced a statistically significant increase in cardiac index (2.0 .+-. 0.4 to 2.7 .+-. 0.5 vs 2.1 .+-. 0.4 to 2.3 .+-. 0.5 liters/min/m2, p < .001), stroke volume index (29 .+-. 6 to 36 .+-. 8 vs 29 .+-. 6 to 30 .+-. 6 ml/m2, p = .02), and right ventricular ejection fraction (30 .+-. 8% to 42 .+-. 7% vs 34 .+-. 8% to 37 .+-. 4%, p < .01) by two-way analysis of variance. We conclude that volume loading does not improve cardiac index in patients with acute RVMI despite a rise in cardiac filling pressures and that infusion of dobutamine, after appropriate volume loading, produces a significant improvement in cardiac index and right ventricular ejection fraction over those after infusion of nitroprusside.