The aim of the present study was to evaluate right ventricular (RV) preload by measurements of right ventricular volumes during aortic clamping and unclamping. Nine patients (aged 67 ± 9 years) undergoing infrarenal aortic aneurysmectomy were monitored with a pulmonary artery catheter equipped with a fast-response thermistor, allowing determination of RV volumes by the thermodilution technique. Anesthesia consisted of a continuous infusion of alfentanil and 50% N20. Aortic clamping resulted in a significant decrease in cardiac index (CI) and a significant increase in systemic vascular resistance (SVR). There was no significant change in right ventricular ejection fraction (RVEF) (from 35% ± 6% to 33% ± 8%) in the presence of a significant decrease in stroke index (from 37.2 ± 9.8 to 31.1 ± 10.0 mL/beat/m2, P < 0.05), indicating a significant decrease in RV end-diastolic volume (from 106 ± 17 to 92 ± 19 mL, P < 0.01). There were no significant changes in cardiac filling pressures. Aortic unclamping was associated with a significant increase in CI and a significant decrease in SVR. There were no significant changes in cardiac filling pressures, RVEF, or RV volumes. Measurements of RV volumes indicated that aortic clamping resulted in a decrease in RV preload, which is usually not demonstrated by measurements of right atrial pressure alone. © 1989.
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