Comparative effects of prenalterol and dobutamine in a canine model of acute ischemic heart failure.

The hemodynamic effects of the inotropic agents prenalterol and dobutamine were compared in a canine model of acute ischemic heart failure following two-vessel coronary artery constriction. Intravenous infusions of both inotropic agents resulted in improvement of cardiac output, left ventricular maximum dP/dt, and contractile force in the nonischemic zone and in a decrease in systemic vascular resistance. No significant changes occurred in ischemic zone contractile force or left ventricular end-diastolic pressure following either inotropic agent compared to saline controls. Significant differences between the two inotropic agents consisted of prenalterol's markedly longer duration of action (hemodynamic half life of 3 hr after discontinuation compared to a value of 1.7 min after dobutamine discontinuation) and greater augmentation of cardiac output at high-dose dobutamine due to greater increases in heart rate. However, similar hemodynamic effects were noted with prenalterol and dobutamine at doses which increased nonischemic contractile force 50%. Both inotropic agents were associated with ventricular arrhythmias in the acute ischemic state. Implications regarding the use of prenalterol and dobutamine in clinical acute ischemic low-output states are discussed.