RESPONSE OF ATRIAL-NATRIURETIC-FACTOR TO POSTURAL CHANGE IN PATIENTS WITH HEART-FAILURE VERSUS SUBJECTS WITH NORMAL HEMODYNAMICS

The response of atrial natriuretic factor to an acute increase in atrial pressures produced by changing from a 45 ° upright to a -15 ° Trendelenburg tilt was examined in 21 patients with heart failure and 8 control subjects with normal hemodynamics. In the control subjects, baseline (45 ° upright tilt) pulmonary capillary wedge and right atrial pressures increased from 3.1 ± 0.9 (mean ± SEM) and 4.4 ± 0.3 mm Hg to 6.9 ± 1.9 and 8.5 ± 0.4 mm Hg, respectively (p < 0.05 for both), 30 min after the -15 ° tilt. Baseline arterial plasma atrial natriuretic factor concentration increased from 34 ± 4 to 44 ± 1 pg/ml (p < 0.05) 30 min after the tilt, with an increase observed in every patient. In the group with heart failure, baseline pulmonary capillary wedge and right atrial pressures increased from 17.5 ± 2.0 and 5.3 ± 1.2 mm Hg to 24.6 ± 1.8 and 9.7 ± 1.3 mm Hg, respectively (p < 0.01 for both), 30 min after the tilt. Plasma atrial natriuretic factor concentration was 326 ± 38 pg/ml at baseline and 347 ± 34 pg/ml (p = NS) 30 min after tilt. Compared with the 7 patients with heart failure who had increased atrial natriuretic factor concentrations after the tilt (responders), the 14 patients with unchanged or decreased atrial natriuretic factor concentrations after the tilt (nonresponders) had a higher baseline right atril pressure and atrial natriuretic factor concentrations. These data suggest that in a subgroup of patients with heart failure, the response of atrial natriuretic factor to an acute increase in atrial pressures is attenuated; this may be related to advanced atrial distension. © 1990.