Effects of nitroprusside-induced reduction of elevated preload and afterload on global and regional ventricular function in acute myocardial infarction.

To evaluate the effects of nitroprusside infusion on left and right ventricular ejection fractions and left ventricular regional wall motion, radionuclide ventriculography with simultaneous hemodynamic assessment was performed before and during nitroprusside infusion in 20 patients with acute myocardial infarction complicated by left ventricular failure and/or systemic arterial hypertension. Nitroprusside produced significant reductions in pulmonary capillary wedge pressure (21 +/- 6 to 13 +/- 5 mm Hg; -38%; p less than 0.001), mean arterial pressure (107 +/- 19 to 90 +/- 13 mm Hg; -15.9%; p less than 0.001), left ventricular end-diastolic volume index (84 +/- 28 to 75 +/- 23 ml/m2; -10.7%; p less than 0.001), and right ventricular end-diastolic volume index (77 +/- 30 to 67 +/- 27 ml/m2; -13.0% p less than 0.007), and significant increases in left ventricular ejection fraction (0.32 +/- 0.12 to 0.37 +/- 0.13; +15.6%; p less than 0.0001), right ventricular ejection fraction (0.37 +/- 0.11 to 0.45 +/- 0.14; +21.6%; p less than 0.001), and stroke volume index (25 +/- 7 to 27 +/- 7 ml/beat m2; +8.0%; p less than 0.03). These beneficial changes in global ventricular performance were accompanied by no change in the regional contractile function of 90% of the abnormally contracting infarct-related left ventricular segments and improved regional wall motion of 34% of noninfarcted but abnormally contracting left ventricular segments. We conclude that nitroprusside-induced reduction of elevated preload and afterload in acute myocardial infarction results in salutary effects on global ventricular function and improved regional function of noninfarcted left ventricular segments but with less prominent effects on regional function of infarcted segments.