Analysis of Intracardiac Flow in Fontan-Palliated Children and Healthy Controls Using Blood Speckle Tracking

Background Cardiac function is critical in patients with functionally univentricular hearts (UVH), including single right ventricle (SRV), single left ventricle (SLV), and double inlet left ventricle (DILV). Abnormal ventricular morphology may alter intracardiac flow dynamics, which are difficult to assess with conventional echocardiography. Blood speckle tracking (BST) enables visualization of intracardiac flow phenomena and quantification of intraventricular energetics. We aimed to describe ventricular energetics in UVH patients after Fontan palliation compared to healthy controls. Methods: Children with UVH (14 SRV, 9 SLV, 6 DILV; median age 84 [60–113] months) and controls (N=30, median age 81 [70–87] months) were prospectively enrolled. BST images were acquired using a clinical ultrasound scanner (GE Vivid E9/E90/95) and analyzed with custom software. Results: Median time post-Fontan was 4.2 [2.1–6.3] years. Vortex formation was qualitatively similar across groups but more complex in DILV. Kinetic energy (KE), energy loss (EL), and vorticity (VO) were significantly higher in controls than all UVH subgroups in both systole and diastole (KE: 134 vs 83.2 mJ/m, p<0.0001; EL: 10.46 vs 5.11 mW/m, p=0.001; VO: 16.99 vs 10.64 Hz, p<0.001). KE, EL, and VO correlated significantly with each other, but not with E-wave velocities. Conclusion: While intracardiac flow patterns are qualitatively similar between UVH and controls, quantitative energetics are markedly reduced in SRV, SLV and DILV. Vortex formation may play a particularly important energy-preserving role in the energy-deprived Fontan circulation .