To investigate the pathophysiology and treatment of right ventricular (RV) contusion we assessed biventricular function via volume expansion in eight open-chest, anesthetized, ventilated dogs. Measurements were obtained before and after RV contusion with a captive bolt pistol and during dobutamine infusion. RV contusion depressed both RV and left ventricular (LV) performance as assessed by classical ventricular function curves (p< 0.05). Dobutamine reduced filling pressure (p< 0.05) and increased cardiac output (CO) (p< 0.01) when infused post contusion. Because, on inspection, the LV was not contused, the apparent depression in LV function is most likely due to reduced diastolic compliance secondary to ventricular interdependence. In support of this possibility, in four dogs, LV performance significantly improved (p< 0.05) when the pericardium was opened. We conclude that RV contusion can depress the relationship between CO and filling pressures in both ventricles and that dobutamine is superior to volume in treating the resultant low cardiac output state.