Two-dimensional echocardiographic quantitation of left ventricular volumes and ejection fraction. Importance of accounting for dyssynergy in short-axis reconstruction models

Abstract

Two-dimensional echocardiography (2DE) was used to measure left ventricular (LV) end-diastolic volume (EDV), end-systolic volume (ESV) and LV ejection fraction (EF). Thirty closed-chest dogs were studied in the control state and, of these, 11 were restudied 1 hour after proximal left anterior descending coronary artery (LAD) occlusion. Two basic left ventricular volume reconstruction models were used, using 2DE-derived LV long-axis length (L) and short-axis cross-sectional areas (A): (1) Simpson's rule with five short-axis areas and (2) a simplified formula (LVV = 5/6 AL) using a single short-axis area, at either the mitral valve (MV) or mid-papillary muscle (MP) level. In the control state, correlations of 2DE against cineventriculography were satisfactory regardless of the reconstruction procedure, but Simpson's rule gave the highest correlation coefficients. With segmental LV dyssynergy distal to the LAD occlusion, correlations for EDV, ESV and EF were good with the comprehensive Simpson's reconstruction (r = 0.89, 0.87, and 0.92, respectively) as well as with the 5/6 AL formula using the MP level area (r = 0.82, 0.87, and 0.92, respectively). However, there was no significant correlation for ESV and EF when the MV short-axis area was used. Thus, in the presence of significant regional asymmetry, satisfactory 2DE quantitation of LV volumes may be obtained with the simplified model 5/6 AL, but the single cross-section being used must adequately reflect the deranged LV geometry. This formula appears particularly suited for clinical 2DE studies in the presence of regional dysfunction, including beat-to-beat or sequential assessment of spontaneous events and evaluation of the effects of interventions.