Plasma atrial natriuretic factor and cyclic GMP in mitral stenosis treated by balloon valvulotomy. Effect of atrial fibrillation

Abstract

To study the relation between plasma atrial natriuretic factor (ANF) and cardiac pressures, we measured plasma ANF in 24 patients with mitral stenosis 30 minutes before and 20 minutes after balloon mitral valvulotomy. All patients were without physical signs of congestive heart failure. Normal sinus rhythm was present in 15 (group 1), whereas the other nine (group 2) had permanent atrial fibrillation. There were no significant differences between groups for basal mean pressures in right atrium (RA), left atrium (LA), and pulmonary artery (PA). Valvulotomy resulted in a fall in both groups (p < 0.001) in LA and PA mean pressures, whereas heart rate, cardiac index, and RA and aorta (AO) pressures did not change significantly. Basal ANF was not different in either group in RA (240 ± 43 vs. 266 ± 35 pg/ml) or AO (441 ± 92 vs. 643 ± 70 pg/ml) but tended to be higher in group 2 in LA (428 ± 88 vs. 682 ± 84 pg/ml; p = 0.059) and PA (488 ± 93 vs. 759 ± 92 pg/ml; p = 0.057). Plasma ANF was the highest in PA, and about 50% ANF was extracted in the systemic circulation. After valvulotomy, plasma ANF was greater (p < 0.05) in group 2 (372 ± 90, 755 ± 152, 805 ± 134, and 707 ± 144 pg/ml) than in group 1 (206 ± 36, 386 ± 47, 429 ± 66, and 421 ± 49 pg/ml), regardless of the site of blood collection (RA, LA, PA, and AO, respectively). PA ANF was correlated with LA pressure (p < 0.05) in group 1 before as well as after valvulotomy, whereas there was no such correlation in group 2. Cyclic GMP (cGMP) in LA was correlated (p < 0.01) with PA ANF in group 1, and LA cGMP (10.0 ± 1.2 and 9.1 ± 1.8 pmol/ml in groups 1 and 2, respectively) was higher (P < 0.05) than PA cGMP (9.1 ± 1.0 and 8.0 ± 1.5 pmol/ml in groups 1 and 2, respectively) before valvulotomy, which suggests the presence of ANF receptors in the pulmonary circulation. Taken together, these results indicate that in patients in sinus rhythm with mitral stenosis, there is an increase in ANF secretion depending on LA pressure. ANF secretion is also high in patients with mitral stenosis and atrial fibrillation but does not respond appropriately to changes in LA pressure. cGMP production in the lungs is related to ANF secretion in patients with sinus rhythm, whereas it seems to be independent in those with atrial fibrillation.