Human atrial natriuretic peptide secretion in precapillary pulmonary hypertension. Clinical study in patients with COPD and interstitial fibrosis.

Human atrial natriuretic peptide (hANP) is stored by granules of both human atria. Atrial distension appears to be a major stimulus for hANP secretion. Precapillary pulmonary hypertension increases right ventricular afterload and may thus cause right atrial distension. We therefore hypothesized that hANP plasma concentrations (1) are higher in the right atrium than in the peripheral vein, (2) are increased in patients with precapillary pulmonary hypertension, and (3) correlate with right atrial pressure. Thirty-three adult patients with chronic obstructive pulmonary disease (COPD) or interstitial fibrosis were examined by right heart catheterization. Mean pressures were measured in the right atrium, pulmonary artery, and pulmonary capillary wedge position, and blood was drawn from the right atrium and from a peripheral vein for determination of hANP levels. In general, hANP plasma levels in the right atrium were significantly higher than in a peripheral vein. Seventeen out of 33 patients had pulmonary hypertension, whereas 16 patients exhibited normal pulmonary artery mean pressures. In all patients, pulmonary arterial wedge pressure was normal. Plasma hANP concentrations were significantly higher in patients with pulmonary hypertension than in patients with normal pulmonary artery pressure. A strong correlation between central or peripheral hANP plasma levels (or both) and mean right atrial pressure could be observed (r = 0.75; p less than 0.001). From these data, we conclude that the increased secretion of hANP in our patients with precapillary pulmonary hypertension appears to be mediated by right atrial distension.