Effect of diuresis on the performance of the failing left ventricle in man.

To determine the effect of diuresis on the performance of the failing left ventricle, we measured cardiac output, pulmonary wedge pressure and M-mode echo left ventricular diastolic dimension before and after diuresis in 13 patients with heart failure. Diuresis increased stroke volume (43 +/- 23 ml to 50 +/- 18 ml (p less than 0.05)) and decreased pulmonary wedge pressure (28 +/- 3 mm Hg to 19 +/- 5 mm Hg (p less than 0.01)), mean blood pressure (100 +/- 14 mm Hg to 88 +/- 10 mm Hg (p less than 0.01)) and systemic vascular resistance (2,059 +/- 622 dynes-sec-cm-5 to 1,783 +/- 556 dynes-sec-cm-5 (p less than 0.05)). Echo left ventricular diastolic dimension was not changed by diuresis (6.0 +/- 0.8 cm to 6.0 +/- 0.8 cm). Percent change in stroke volume correlated with systemic vascular resistance (r = 0.60, p less than 0.05) and with left ventricular diastolic dimension (r = 0.62, p less than 0.05) but not with pulmonary wedge pressure (r = 0.12) or right atrial pressure (r = 0.04). Thus, diuresis improved the performance of the failing ventricle and reduced afterload, but it did not alter left ventricular diastolic dimension, an index of preload. These data suggest that diuresis improves ventricular function by decreasing afterload.