Aortic input impedance in mild to moderate chronic congestive heart failure: lack of interrelation with neurohormonal activation.

Abstract

Patients with chronic congestive heart failure (CHF) have activated neurohormonal systems, which may induce vasoconstriction. In addition, the arterial wall sodium content may increase and could have direct trophic effects on vascular smooth muscle cells. These mechanisms might elevate left ventricular (LV) pulsatile load. We measured aortic input impedance to find out the LV pulsatile load and neurohormonal activation in 20 patients with mild to moderate chronic CHF. Cardiac index (2.2 +/- 0.3 l.min-1 x m-2) and LV ejection fraction (38 +/- 4%) were reduced, pulmonary wedge pressure was elevated (21 +/- 2 mmHg). Plasma norepinephrine levels (462 +/- 62 pg.ml-1), plasma renin concentration (12 +/- 4 ng.AI.ml-1h-1), plasma levels of atrial natriuretic peptide (408 +/- 64 pg.ml-1) and, to a slight degree, plasma arginine vasopressin (1.1 +/- 0.3 pg.ml-1) were increased. Characteristic impedance, Zc, was within the normal range (80 +/- 6 dyn.s.cm-5) and showed no significant correlation with the degree of neurohormonal activation (r-values: -0.05 to -0.35). Our data demonstrate that in early stages of CHF stimulation of the neurohormonal systems does not significantly elevate LV pulsatile load; therefore there is no substantial alteration in the physical properties of the great arteries.