The Neurohumoral and Hemodynamic Response to Orthostatic Tilt in Patients with Congestive Heart Failure

Thirty-five patients with varying degrees of congestive heart failure were subjected to 60° upright tilt. Eight of the patients with normal resting hemodynamics had elevated resting plasma norepinephrine levels (PNE) (p < 0.001), but their response to upright tilt was similar to that in normal subjects: All had increases in heart rate, plasma norepinephrine (from 263 ± 32 to 483 ± 78 pg/mg, p < 0.02) and plasma renin activity (from 4.8 ± 0.9 to 13.7 ± 7.6 ng/ml/hour, p < 0.05). In 27 patients with high resting pulmonary wedge pressure and low cardiac index, resting PNE was higher (668 ± 71 ng/ml), but PNE, plasma renin activity and heart rate did not increase significantly during tilt despite a fall in pulmonary capillary wedge pressure and cardiac index. In 18 of these patients, PNE rose during tilt, whereas in nine it did not change or fell; the regting hemodynamics and the hemodynamic response to tilt were not significantly different in these two groups. These data suggest that an abnormality of mechanoreceptor or baroreceptor function is common in patients with CHF. This abnormality corresponds in part to the severity of the resting hemodynamic abnormality, but among patients with severe CHF, the reflex neurohumoral abnormality may provide independent information about the severity of the disease.