Detailed quantification of right ventricular function in tetralogy of Fallot: a 3D echocardiography study

Tetralogy of Fallot (ToF) is a congenital heart disease requiring surgical repair in early childhood. Affected patients cope with severe right ventricle (RV)-related morbidity during adulthood, which is mostly attributed to RV remodelling. Improved understanding of RV remodelling patterns is essential for advancements in clinical decision-making and treatment planning. Consequently, a method to enable detailed quantification of directional components of RV function was developed using 3D echocardiography (3DE).

From RV-focused 3DE studies of 50 ToF patients and 50 healthy controls, 3D dynamic RV meshes were obtained using commercially available software (TomTec 4D RV-Function). A software tool was developed in-house to decompose RV contraction in longitudinal (LT), radial, and anteroposterior (AP) motion directions. Their respective contributions to RV ejection fraction (EF) were calculated. The AP contraction component was identified as the main contributor in RV function deterioration, showing significant relative reduction in ToF patients compared with healthy controls [38% (31-42) vs. 40% (37-44), P = 0.004]. Conversely, the LT direction showed significant relative increase in ToF compared with healthy controls [28% (26-33) vs. 26% (23-31), P = 0.009].

Our custom software allowed for effective directional decomposition of RV EF, enabling detailed quantification of RV function in patients with ToF. RV function deterioration was primarily due to a decreased contribution of AP wall motion to RV EF, whereas LT contribution showed relative increase. These findings highlight the need for more detailed RV function assessment for improved understanding of RV remodelling.