Right ventricular injury in young swine: Effects of catecholamines on right ventricular function and pulmonary vascular mechanics

Acute right ventricular (RV) injury is commonly encountered in infants and children after cardiac surgery. Empiric medical therapy for these patients results from a paucity of data on which to base medical management and the absence of animal models that allow I rigorous laboratory testing. Specific ally, exogenous catecholamines have unclear effects on the injured right ve ntricle and pulmonary vasculature in the young. Ten anesthetized piglets (9 -12 kg) were instrumented with epicardial transducers, micromanometers, and a pulmonary artery Row probe. RV injury was induced with a cryoablation pr obe. Dopamine at 10 mug/kg/min, dobutamine at 10 mug/kg/min, and epinephrin e (EP) at 0.1 mug/kg/min were infused in a random older. RV contractility w as evaluated using preload recruitable stroke work. Diastolic function was described by the end-diastolic pressure-volume relation, peak negative deri vative of the pl pressure waveform, and peak filling rate. In addition to r outine hemodynamic measurements, Fourier transformation of the pressure and flow waveforms allowed calculation of input resistance, characteristic imp edance, RV total hydraulic power, and transpulmonary vascular efficiency. C ryoablation led to a stable reproducible injury, decreased preload recruita ble stroke work, and impaired diastolic function as measured by all three i ndices. Infusion of each catecholamine improved preload recruitable stroke work and peak negative derivative of the pressure waveform. Dobutamine and EP both decreased indices of pulmonary vascular impedance, whereas EP was t he only inotrope that significantly improved transpulmonary vascular effici ency. Although all three inotropes improved systolic and diastolic RV funct ion, only EP decreased input resistance, decreased pulmonary vascular resis tance, and increased transpulmonary vascular efficiency.