Abstract Body (Do not enter title and authors here): Background
Accurate assessment of right ventricular (RV) volume is crucial for monitoring patients with congenital heart defects (CHD). However, due to the RV's complex geometry, 2D transthoracic echocardiography (2D TTE) is challenging, and MRI is commonly used to evaluate RV volume. Despite its accuracy, MRI has several limitations: it lacks bedside imaging, is time-consuming, costly, and often requires sedation in CHD patients. Therefore, this study aimed to develop a reliable, simple, and quick method for calculating RV volume using 2D TTE.
Methods
Standard apical four-chamber (4CH) and parasternal short-axis (SAX) views were obtained using 2D TTE in patients with CHD during routine follow-up (Figure 1). RV volumes were calculated using the conventional ellipsoidal shell model formula, a truncated cone model and a novel approach based on a cone model. The results were compared with RV volumes obtained via MRI.
Results
Forty CHD patients (median age: 23.1 years) were included. The proposed cone-based formula (CBF) showed excellent correlation with MRI-derived RV volumes (systolic: r = 0.95, 95% CI: 0.91–0.97; diastolic: r = 0.92, 95% CI: 0.86–0.96), with intercepts of 2.5 ml (systolic) and 25.45 ml (diastolic) (Figure 2). The mean difference from MRI volumes was 0.1 ml (0.001%, SD ±13.3) for systolic and 5.2 ml (3%, SD ±28.2) for diastolic volume. Based on root mean square error (RMSE)—considered the most appropriate metric of model fit under linear assumptions—CBF outperformed the ellipsoidal shell model (RMSE 13.2/28.4 ml vs. 20.8/52.6 ml, systolic/diastolic) and the truncated cone model (RMSE 25.1/42.3 ml, systolic/diastolic) (Figure 3). These findings held true even in patients with RV enlargement (mean RVEDVi: 98.6 ml/m2)
Conclusion
Our method shows excellent alignment with the data, as indicated by the low y-axis intercept and RSME, while maintaining strong correlation with MRI measurements. It offers an accurate and rapid method for bedside assessment of RV volume, enhancing prompt and precise clinical decision-making.