• E L Honkonen, L Kaukinen, S Kaukinen, E J Pehkonen, and P Laippala.
• Department of Anesthesia and Intensive Care, Tampere University Hospital, Finland.
• J. Cardiothorac. Vasc. Anesth. 1998 Dec 1; 12 (6): 647-53.

ObjectiveTo 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.DesignA prospective, randomized, double-blind, cross-over, clinical study.SettingUniversity hospital.ParticipantsTwenty patients with proximal total stenosis of the right coronary artery studied immediately after coronary artery surgery.InterventionsTreatment 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 ResultsCentral 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). Iloprost 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.ConclusionThe findings suggest that dopexamine is more effective than iloprost for support and unloading of the postoperatively disturbed RV in terms of RVEF and end-systolic 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.

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