Digital Ventriculography: Valid On-Line Calculation of Cardiac Volumes by Corrected Computer Densitometry in Coronary Artery Disease

Abstract

Cardiac catheterization facilitates the assessment of left ventricular function in coronary artery disease (CAD). Digital left ventriculography offers the potential for an on-line quantitative determination of left ventricular end-diastolic volume (LVEDV) and left ventricular end-systolic volume (LVESV). These are routinely evaluated by the area- length method (ALM), which is considered as a standard. Densitometry (DENS) is an alternative method but may lead to calculated underestimations. The purpose of this study was to investigate the accuracy of corrected DENS for LVEDV and LVESV in comparison with ALM in single-plane 30° right anterior oblique (RAO) projection. The computer densitometric correction equation was adapted from the linear regression analysis (y=0.86x+2.73) in cardiac models and applied to the analysis of digital left ventriculograms in patients suffering from CAD. The study of cardiac models yielded highly significant correlations ( r≥ 0.9; P≤ 0.001) between true volumes and both DENS and ALM. DENS and ALM correlated highly signif icantly ( r≥ 0.9; P ≤ 0.001) with a low standard error of estimate (SEE) of ±9.5 mL. The comparison of DENS and ALM in 44 patients' digital ventriculograms exhibited highly significant (r=0.74; P ≤ 0.001) correlations for noncorrected and corrected LVEDV. Systematic underestimation by DENS of LVEDV disappeared after correction and SEE decreased from ±23.7 to ±19.2 mL. DENS and ALM correlated highly significantly for LVESV (r=0.78; P ≤ 0.001; SEE ± 15.6 mL ± 13.5 mL, respectively) after correction. Following correction, mean values for DENS increased from 116 ±32 to 132 ±37 mL (LVEDV) and 50 ±22 to 55 ±25 mL (LVESV). For ALM, mean values decreased from 159 ±35 to 127 ±28 mL (LVEDV) and 55 ±25 to 46 ±21 mL (LVESV). This study shows that LVEDV and LVESV can be reliably analyzed on-line by corrected computer densitometry. Method-related errors of both DENS and ALM are present and account for minor volume deviations.