Anatomic And Hemodynamic Changes In Single Ventricle Patients 3-9 Months After Fontan To The Teenage Years: Insights From Cardiac Magnetic Resonance And Computational Fluid Dyanmics

Introduction: Little is known of baseline cardiac magnetic resonance (CMR) data in single ventricle (SV) pts immediately after Fontan. In addition, total cavopulmonary connection (TCPC) changes from this point to the teen years may shed some light regarding how to optimize clinical outcome. Hypothesis: Anatomic, hemodynamic and computational fluid dynamic (CFD) parameters are significantly altered as pts age. Methods: SV pts 3-9 months after Fontan and teens were studied with CMR. Anatomy, flows and CFD modeling were performed. Significance = P<0.05. Results: 22 were 3-9 months after Fontan (age 3±1.1 yrs, 0.6±0.3 yrs after Fontan) & 25 were teens (age 16±1.8 yrs, 14.1±2.2 yrs after Fontan). Although a higher indexed powerloss (iPL) in teens almost reached significance, Reynold’s number & particle resident time (time a red blood cell remains in the TCPC) were greater in teens than younger pts (table). Superior vena cava (SVC) pulsatility index (PI) was greater in younger pts while inferior vena cava (IVC) PI was greater in teens, owing to the primary caval return changing from SVC to IVC as pts age (table). Both cardiac index & caval return decreased in teens while hepatic flow distribution (HFD) became more evenly distributed in teens (table). The % TCPC stenosis at its narrowest point was greater in teens (42.8 %) than younger pts (20.9%), P=0.009. In teens, iPL (R=0.39) and % TCPC stenosis (R=0.62) correlated with time from Fontan (P<0.39 for both). Conclusion: In teens, iPL correlated with time from Fontan. Significant increase in particle resident time & Reynold’s number occur as SV pts age, with increased narrowing of the TCPC while HFD became more even. SVC PI is higher in younger pts while IVC PI is higher in teens. Cardiac index & caval return both decrease as pts age. These data serve as baseline information in the immediate post-operative state and may be used to aid in designing improved Fontan reconstruction to optimize clinical outcome.