The Effects of Pathophysiological Increments in Brain Natriuretic Peptide in Left Ventricular Systolic Dysfunction

Plasma levels of brain natriuretic peptide (BNP) are raised in patients with left ventricular impairment and may play a role in the adaptation to left ventricular impairment. Manipulation of BNP levels may have therapeutic potential. The effects of BNP have not been well studied in patients with left ventricular impairment. We studied the effects of low-dose BNP infusion, reproducing the increment in plasma BNP seen with progression from mild to severe heart failure in patients with impaired left ventricular systolic function. BNP was infused in a placebo-controlled, single-blind, crossover design at a rate of 3.3 pmol x kg(-1) x min(-1) over 4 hours to 8 patients with a history of congestive heart failure and persistent impairment of left ventricular systolic function (left ventricular ejection fraction <35%). Endocrine, renal, and hemodynamic effects were measured. Compared with time-matched placebo-control, BNP infusion decreased mean systemic arterial pressure (peak decrease, 17.1 mm Hg; P=.04), mean pulmonary artery pressure (peak decrease, 6.1 mm Hg; P=.007), mean pulmonary capillary wedge pressure (peak decrease, 5.5 mm Hg; P=.04), and systemic vascular resistance (peak decrease, 1400 dyne s(-1) cm(-5); P=.015), but cardiac output and heart rate were unchanged. Urinary volume and urinary excretion of sodium and potassium were not altered. BNP infusion increased plasma cGMP (2.3-fold change, P=.002). Plasma atrial natriuretic peptide levels were increased for the first hour of BNP infusion (peak increase, 11.5 pmol/L; P=.005). Plasma aldosterone levels were unchanged during but increased over time-matched control levels after the end of the BNP infusion (peak increase, 90 pmol/L; P=.02). Plasma renin activity and cortisol and catecholamine levels were unchanged. Low-dose infusion of BNP causes favorable hemodynamic changes and relative neurohormonal suppression but has attenuated renal effects in patients with impaired left ventricular systolic function.