Longitudinal Intracardiac Right Ventricular Flow Analysis in Infants With Hypoplastic Left Heart Syndrome in Interstage I Using Novel Doppler Velocity Reconstruction.

Background: Echocardiography provides noninvasive frontline assessment of right ventricular (RV) function in hypoplastic left heart syndrome (HLHS). However, conventional metrics do not quantify RV intracardiac hemodynamics. A novel Doppler velocity reconstruction measures kinetic energy, vortex strength, and flow energy loss through conventional color Doppler acquisitions. We investigated longitudinal changes in RV intracardiac flow in infants with HLHS during the critical interstage period, hypothesizing that these trends may inform disease progression.

Methods: This was a single-center, retrospective analysis of patients with HLHS who underwent stage 1 palliation (bilateral pulmonary artery bands/hybrid palliation or Norwood operation). Echocardiographic studies at 5 time points from before to 6 months after surgery were selected for postprocessing. Apical views of the RV with adequate color Doppler imaging were analyzed. Significant tricuspid regurgitation was defined as vena contracta jet width ≥2.5 mm. Adverse events included death, heart transplant, use of ventricular assist device, or extracorporeal membrane oxygenation.

Results: Thirty-six patients with HLHS (21 hybrid, 15 Norwood) were included. Flow energy loss, vortex strength, and kinetic energy increased over time for all interstage patients with HLHS (P<0.0001) and correlated with RV size, body surface area, and E wave. Significant tricuspid regurgitation was associated with elevated flow energy loss and vortex strength (P=0.0007 and P<0.0001). Adverse events showed early changes in flow parameters and altered trends over the interstage period (vortex strength, P<0.0001; kinetic energy, P=0.0009).

Conclusions: Doppler velocity reconstruction can assess RV intracardiac flow in infants in HLHS interstage I. While the results should not be used to interpret the surgical strategies, the longitudinal analysis of intracardiac flow may elucidate diastolic filling dynamics, with deviations associated with adverse events throughout the interstage period.