The acute hemodynamic effects of ethacrynic acid and furosemide in patients with chronic postcapillary pulmonary hypertension.

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Abstract
The acute hemodynamic effects of either ethacrynic acid or furosemide were studied in 27 patients who underwent diagnostic right and transseptal left heart catheterization. Twenth-three patients had postcapillary pulmonary hypertension secondary to isolated or predominant mitral stenosis. Of these, 21 patients were in New York Heart Association functional class III, and one each in class II and IV. In the remaining four patients pulmonary artery pressures were normal. Two patients had aortic stenosis and one each coronary artery disease and nonobstructive cardiomyopathy. All four patients were in class II. Cardiac index, pressures, and pulmonary blood volume (PBV) were measured in the control state and 20, 40, and 60 min after diuretic administration. Pulmonary extravascular fluid volume (PEV) was measured in the control state and at 60 min post drug infusion. A similar hemodynamic response was observed for each drug. Significant reductions in pulmonary artery and left atrial mean pressures, cardiac index, and plasma volume occurred over the one hour observation period and were accompanied by a significant duiresis. However, despite recutions in central pressures and blood flow, PBV, ev, and PEV/PBV remained unchanged, as did systemic arterial pressure. Since 23 of the subjects had postcapillary pulmonary hypertension it is postulated that the failure of PBV to decrease significantly despite significant decreases in pulmonary artery mean pressure is related to altered pressure volume characteristics in the pulmonary vascular bed in which the lung is operating on a steep portion of its pressure volume curve. The failure of the PEV to decrease supports the concept that the pulmonary extravascular space is relatively resistant to early decreases in pulmonary capillary pressure induced acutely. The failure of the pulmonary extravascular fluid volume to decrease despite a fall in plasma volume and pressures corresponds to the well recognized delay in resolution of radiologic evidence of pulmonary congestion.