Raised circulating plasma levels of atrial natriuretic peptide in adolescent and adult patients with cystic fibrosis and pulmonary artery hypertension

Since pulmonary artery hypertension (PH) complicates advanced stages of cystic fibrosis (CF), we wondered whether plasma concentrations of h-ANP would be increased in adult patients with CF. Furthermore, if only the right ventricle is faced with an increased afterload in these patients, the increased h-ANP plasma levels should stem primarily from the right atrium. To test this hypothesis we studied 12 adult patients with CF in a clinically stable condition using right heart catheterization. Mean pressures were measured in the right atrium (Pra) and pulmonary artery (Ppa), pulmonary capillary wedge (PCWP) position, and blood were drawn from the pulmonary artery and from a peripheral vein to determine h-ANP. Plasma levels in the pulmonary artery were significantly higher than in a peripheral vein (54.3 +/- 6.0 pg/ml vs. 32.2 +/- 4.4 pg/ml; p less than 0.001). Four of the 12 patients had PH (Ppa, 25.8 +/- 2.9 mmHg) whereas 8 patients exhibited normal pulmonary artery pressures (Ppa, 15.9 +/- 0.7 mmHg). Patients with PH had higher Pra (4.2 +/- 0.4 mmHg) than patients with CF without PH (1.9 +/- 0.7 mmHg; p less than 0.05). Plasma h-ANP concentrations were significantly higher in patients with CF with PH (70 +/- 10.4 pg/ml in the pulmonary artery; 42.6 +/- 4 pg/ml in a peripheral vein) than in patients with normal pulmonary artery pressure (43 +/- 3.3 pg/ml in the pulmonary artery; p less than 0.01; 24.7 +/- 5.6 pg/ml in a peripheral vein; p less than 0.05). Although our results are derived from a small group of patients with CF, we conclude from our results that in patients with CF PH may cause increased h-ANP secretion. The right atrium seems to be a major source.