Comparison of hemodynamic actions of pirbuterol and dobutamine on cardiac function in severe congestive heart failure

Abstract

There is considerable interest in the development of beneficial oral inotropic agents for sustained ambulatory management of patients with severe chronic congestive heart failure. Therefore, the hemodynamic actions of the oral beta adrenergic receptor agonist pirbuterol and of intravenous dobutamine were compared in nine patients with severe heart failure. Both agents produced similar effects on ventricular pump function: The cardiac index was markedly increased from 1.8 to 2.6 liters/min per m 2 (p < 0.005) by dobutamine and from 1.8 to 2.9 liters/min per m 2 (p < 0.001) by pirbuterol; stroke index was increased from 24 to 32 ml/beat per m 2 (p < 0.02) by dobutamine and from 23 to 35 ml/beat per m 2 (p < 0.001) by pirbuterol; the stroke work index was increased from 19 to 27 g-m/m 2 (p < 0.005) by dobutamine and from 20 to 28 g-m/m 2 (p < 0.005) by pirbuterol. However, although dobutamine did not change mean blood pressure or left ventricular filling pressure (p < 0.05), pirbuterol modestly decreased mean blood pressure from 83 to 75 mm Hg (p < 0.02) and moderately decreased left ventricular filling pressure from 23 to 18 mm Hg (p < 0.005). Dobutamine reduced total systemic vascular resistance 22 percent from 2,049 to 1,582 dynes s cm −5 (p < 0.001), whereas pirbuterol reduced this index 42 percent (p < 0.05 versus dobutamine) from 2,068 to 1,150 dynes s cm −5. Neither agent altered heart rate or the heart rate-systolic blood pressure product (p < 0.05). Thus, oral pirbuterol has dobutamine-like beneficial hemodynamic effects on left ventricular pump function but causes a greater decrease in total systemic vascular resistance consistent with the combined inotropic and peripheral vasodilator actions of this oral beta adrenergic receptor agonist. These salutary hemodynamic responses suggest that oral pirbuterol may be useful for the prolonged treatment of severe chronic congestive heart failure.