From simple measurement to a complex form: right ventricular volumetry using 2D-echocardiography-a retrospective...

Assessment of right ventricular volume is crucial for monitoring patients with congenital heart defects. However, due to the right ventricle's complex geometry, 2D echocardiography is challenging and MRI is commonly used to evaluate right ventricular volume. However, MRI has several limitations: it lacks bedside imaging, is time-consuming, and often requires sedation in patients with congenital heart defects. Therefore, we aimed to develop a reliable and simple method for calculating right ventricular volume using 2D echocardiography.

Standard apical 4-chamber and parasternal short-axis views were obtained using 2D echocardiography in 40 congenital heart defects patients. Right ventricular volumes were calculated using an ellipsoidal shell model, a truncated cone model and a novel approach based on a cone model: $V_{\mathrm{RV}}=\frac{2}{3}\frac{\left(A_{\mathrm{SAX}}+\frac{1}{8}\pi d_{\mathrm{TV}}^2\right)A_{4\mathrm{CH}}}{d_{\mathrm{TV}}}$ . The results were compared with right ventricular volumes obtained via MRI. The proposed cone-based model demonstrated excellent correlation to right ventricular volumes obtained by MRI (systolic: ICC = 0.98 (95% CI 0.95-0.99)/diastolic: ICC = 0.96 (95% CI 0.92-0.98)). The mean difference from MRI-measured systolic volume was 0.1 mL (SD ± 13.3) and from diastolic volume 5.2 mL (SD ± 28.2). Based on the root mean square error (RMSE) our cone model (RMSE 13.2 mL/28.4 mL systolic/diastolic) demonstrates significantly better predictive accuracy than the traditional ellipsoidal shell model (RMSE 20.8 mL/52.6 mL systolic/diastolic) and the truncated cone model (RMSE 25.1 mL/42.3 mL systolic/diastolic).

Our method shows excellent alignment with MRI data. It offers an accurate and rapid method for bedside assessment of right ventricular volume with 2D echocardiography, enhancing prompt and precise clinical decision-making.