Responsiveness of Plasma Atrial Natriuretic Factor to Short-Term Changes in Left Atrial Hemodynamics After Percutaneous Balloon Mitral Valvuloplasty

To assess the effect of short-term alteration of left atrial pressure and volume on the circulating plasma level of atrial natriuretic factor, 11 patients with left atrial hypertension due to mitral stenosis were studied at the time of percutaneous balloon mitral valvuloplasty. Hemodynamic measurements and plasma atrial natriuretic factor levels were obtained before, immediately (5 to 10 min) after and 24 h after valvuloplasty, arid echocardiographic left atrial size was determined before and 24 h after valvuloplasty. Immediately after valvuloplasty, left atrial pressure decreased from 28 ± 2 to 10 ± 1 mm Hg (p > 0.0005), mitral pressure gradient decreased from 20 ± 2 to 7 ± 1 mm Hg (p > 0.0005), mitral valve area increased from 0.8 ± 0.1 to 1.9 ± 0.2 cm2 (p > 0.0005) and plasma atrial natriuretic factor level rose from 249 ± 42 to 348 ± 50 pg/ml (p > 0.01). This short-term rise in atrial natriuretic factor level may reflect a transient increase in left atrial pressure associated with balloon occlusion of the mitral valve. Twenty-four hours after valvuloplasty, pulmonary capillary wedge pressure was 15 ± 1 mm Hg (p > 0.001 versus left atrial pressure before valvuloplasty, p > 0.005 versus left atrial pressure immediately after valvuloplasty), left atrial volume had decreased to 58 ± 8 from 81 ± 10 cm3 before valvuloplasty (p > 0.001), left atrial wall tension had declined to 24 ± 7 from 48 ± 16 dynes/cm x 103 (p > 0.002) and plasma atrial natriuretic factor level had fallen to 98 ± 16 pg/ml (p > 0.001 versus before valvuloplasty, p > 0.0005 versus immediately after valvuloplasty). Atrial natriuretic factor level correlated with left atrial pressure (r = 0.69, P > 0.001), volume (r = 0.67, P > 0.002) and wall tension (r = 0.75, P > 0.001). These results indicate that secretion of atrial natriuretic factor is sensitive to short-term alteration of left atrial stretch in patients with chronic elevation of left atrial pressure.