Effects of Dopamine and Olprinone on Ventricular Energetics in Sevoflurane- Induced Acute Left Ventricular Depression in Dogs

Objective: The purpose of this study was to compare the effects of dopamine and a new phosphodiesterase (PDE)–3 inhibitor, olprinone, on hemodynamics and myocardial energetics in dogs with acute myocardial depression. Design: Prospective, randomized, crossover study. Setting: University animal laboratory. Subjects: Mongrel dogs. Interventions: Eight open-chest, barbiturate-anesthetized dogs with instruments for measurement of left ventricular pressure and volume were exposed to 2 MAC (minimum alveolar concentration) of sevoflurane to induce acute myocardial depression. Each dog was randomly assigned for either infusion of dopamine (5 μg/kg/min) for 15 minutes or bolus of olprinone (10 μg/kg), followed by an infusion (0.3 μg/kg/min) for 30 minutes. Treatment was crossed over after a washout period of 90 minutes. Measurements and Main Results: For analysis of ventricular energetics, ventriculoarterial coupling was assessed using the ratio of arterial elastance to end-systolic pressure-volume relation and mechanical efficiency was calculated using the ratio of external work to pressure-volume area. Measurements were performed prior to sevoflurane administration, and before and after treatment. Two MAC of sevoflurane significantly impaired ventriculoarterial coupling and mechanical efficiency. Both olprinone and dopamine improved ventriculoarterial coupling and mechanical efficiency to similar degrees, but by different mechanisms. Olprinone improved ventricular energetics at a lower energy expenditure, probably because of olprinone’s vasodilating effect, which augments energy transfer from the ventricle into the systemic circulation. Conclusion: Although both dopamine and olprinone improve sevoflurane-induced impairment of ventricular energetics, olprinone accomplishes this with lower ventricular energy expenditure.