LEFT VENTRICULAR END-DIASTOLIC VOLUME FROM EJECTION FRACTION AND STROKE VOLUME IN PIGS DURING INFERIOR VENA CAVAL OCCLUSION

Abstract

Purpose: Measurement of left ventricular (LV) end-diastolic volume (EDV) is essential for assessment of intraoperative systolic and diastolic LV function. In a study submitted for review, our laboratory demonstrated the validity of stroke volume divided by ejection fraction (SV/EFa) for calculation of LV EDV in the steady-state, but the utility of this measurement, EDVsv, during dynamic changes in preload has not been examined. This study was undertaken to validate EDVsv during preload reduction. The utility of compliance data based on EDVsv was also examined. Methods: Five anesthetized pigs (40–45kg) underwent median sternotomy and pericardiotomy. An ultrasound transit-time flow probe was placed on the ascending aorta to provide cardiac output (CO). A micromonameter provided LV EDP. LV short-axis cross sections (SACS) and ECGs were also obtained. These data were obtained during the steady-state and during inferior vena caval (IVC) occlusion. End-diastolic and end-systolic areas (EDA and ESA) were measured to obtain EFa. EDVsv was determined from CO, heart rate, and EFa during IVC occlusion. EDV in the steady-state (EDVe) was also determined using a three-plane echocardiography model. EDVe was compared to the corresponding EDA and that relation was used to derive EDVeda from EDAs measured during IVC occlusion. The pressure-EDVsv relation during the IVC occlusion was then compared to the pressure-EDVeda relation. Results: Correlation coefficients for linear and pressure-volume relation analysis generally ranged from 0.70 to 0.99. The two methods (EDVsv and EDAeda) for measuring LV EDV generated compliance curves with comparable α and β-values (p>0.05). The EDVsv method may facilitate real-time determination of LV mechanics. Accuracy and utility of EDVsv in these preliminary studies are acceptable and merit further investigation.