This study was conducted to evaluate the acute efficacy and safety of intravenous administration of nicorandil in patients with acute heart failure syndromes (AHFS), under noninvasive hemodynamic assessment with transthoracic Doppler echocardiography. After baseline hemodynamic measurements, initial bolus and 48-hour continuous intravenous nicorandil infusion were begun in 14 hospitalized patients with AHFS. After 2-hour infusion, estimated pulmonary capillary wedge pressure was reduced from 21.4 +/- 6.4 to 17.5 +/- 5.2 mm Hg (P < 0.05) and was sustained for 48 hours to 16.2 +/- 5.5 mm Hg (P < 0.05). A significant increase in estimated cardiac output was observed at 2 hours, from 4.0 +/- 1.0 to 4.8 +/- 1.3 L/min (P < 0.05). This increase was sustained for 48 hours to 5.8 +/- 1.8 L/min (P < 0.05). The high blood pressure (BP) group (baseline systolic BP > or = 140 mm Hg, n = 7) exhibited significant decrease in systolic BP (from 156.7 +/- 14.2 to 135.4 +/- 13.3 mm Hg, P < 0.05). In contrast, there was no change in systolic BP in the low BP group (baseline systolic BP < 140 mm Hg, n = 7) over 48 hours (from 107.6 +/- 20.4 to 107.7 +/- 17.4 mm Hg, P = not significant). The results of this study demonstrate the acute hemodynamic efficacy and safety of intravenous administration of nicorandil and also suggest the usefulness of noninvasive echocardiographic hemodynamic evaluation in the urgent phase of AHFS.