Dopexamine unloads the impaired right ventricle better than iloprost, a prostacyclin analog, after coronary artery surgery

Objective: To evaluate the ventricle-unloading properties of dopexamine and iloprost and to compare their effects on right ventricular (RV) function a nd oxygen transport in patients with low RV ejection fraction (RVEF) after cardiac surgery. Design: A prospective, randomized, double-blind, crossover, clinical study. Setting: University hospital. participants: Twenty patients with proximal total stenosis of the right cor onary artery studied immediately after coronary artery surgery. Interventions:Treatment drugs were administered in a random order in doses equipotent with respect to cardiac output response. Infusion rates were inc reased stepwise to induce a 25% increase in cardiac index. A washout period of 60 minutes was allowed between treatments. Measurements and Main Results: Central hemodynamics, RV function assessed b y the EF (fast-response thermodilution), end-systolic and end-diastolic vol umes, and systemic oxygenation were measured before and after the first dru g, after the washout period, and after the second drug. Central filing pres sures remained constant during treatments. Both drugs decreased pulmonary v ascular resistance index, but iloprost was more effective (p < 0.05). Ilopr ost decreased mean arterial and pulmonary artery pressure, which were unaff ected by dopexamine. Dopexamine increased EF significantly more than ilopro st (p < 0.001). End-systolic volume index decreased subsequent to dopexamin e only (p < 0.001). Iloprost increased intrapulmonary shunt more than dopex amine (p < 0.001). Changes in oxygen delivery, consumption, and extraction were similar. Conclusion:The findings suggest that dopexamine is more effective than ilop rost for support and unloading of the postoperatively disturbed RV in terms of RVEF and end-systolic volume. The reduction of pulmonary vascular resis tance after administration of iloprost without a decrease in end-systolic v olume might not be considered a reduction of RV afterload. Iloprost increas es the pulmonary shunt fraction, however, more than dopexamine, indicating a more prominent vasodilator effect. Copyright (C) 1998 by W.B. Saunders Co mpany.