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

Abstract

Objective: To evaluate the ventricle-unloading properties of dopexamine and iloprost and to compare their effects on right ventricular (RV) function and 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 coronary 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 increased 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 by the EF (fast-response thermodilution), end-systolic and end-diastolic volumes, and systemic oxygenation were measured before and after the first drug, after the washout period, and after the second drug. Central filling pressures remained constant during treatments. Both drugs decreased pulmonary vascular resistance index, but iloprost was more effective ( p < 0.05). lloprost decreased mean arterial and pulmonary artery pressure, which were unaffected by dopexamine. Dopexamine increased EF significantly more than iloprost ( p < 0.001). End-systolic volume index decreased subsequent to dopexamine only ( p < 0.001). Iloprost increased intrapulmonary shunt more than dopexamine ( p < 0.001). Changes in oxygen delivery, consumption, and extraction were similar. Conclusion: The findings suggest that dopexamine is more effective than iloprost for support and unloading of the postoperatively disturbed RV in terms of RVEF and endsystolic volume. The reduction of pulmonary vascular resistance after administration of iloprost without a decrease in end-systolic volume might not be considered a reduction of RV afterload. Iloprost increases the pulmonary shunt fraction, however, more than dopexamine, indicating a more prominent vasodilator effect.