Right ventricular flow dynamics in dilated right ventricles. Energy loss estimation based on blood speckle tracking echocardiography in children

Background: Volume loading caused by a large atrial septal defect (ASD) or pulmonary insufficiency (PI) after Tetralogy of Fallot repair (rTOF) results in right ventricular (RV) dilatation. Ventricular flow dynamics in these two conditions are not well characterized. Using novel blood speckle tracking echocardiography, we compared RV flow dynamics in children with ASD and rTOF by calculating ventricular energy-loss (EL). Methods: Children with rTOF with severe PI, large ASD and healthy controls (CTL) were included. RV 3 and 4 chamber views were acquired using a modified clinical scanner with research software enabling the acquisition of blood speckle images at sufficient rates for blood speckle tracking (kHz range). Blood velocity fields and EL were then obtained (figure1). Results: Demographics were similar between the groups (table1). When normalized for BSA, EL in diastole was significantly higher in the ASD and TOF groups compared to CTL while no significant differences were observed between ASD and rTOF groups. Energy loss ratio between diastole and systole was similar between ASD and rTOF, but was significantly higher in both groups compared to CTL. Locations of maximal EL were similar in all groups in systole, occurring in the right ventricular outflow tract (RVOT), and in early diastole, around the tricuspid valve leaflets. In rTOF however, additional early diastolic EL was noted in the RV apex. Qualitative assessment of flow imaging shows colliding PI and tricuspid flows at the RV apex in rTOF(figure 1). Conclusion: Energy losses incurred in diastole relative to systole are similar in rTOF and ASD but greater compared to healthy control. In early diastole and systole, all groups share similar regions of EL whereas in rTOF, there is an additional area of EL at the RV apex, corresponding to colliding tricuspid inflow and severe PI. Blood speckle tracking echocardiography is a promising new tool to further the quantitative and qualitative understanding of ventricular flow dynamics and their effects on ventricular remodeling.