Pediatric Track Session
SCMR 22nd Annual Scientific Sessions
Apicocaval juxtaposition (ACJ) is a rare form of single ventricle congenital heart defects, where the cardiac apex points towards the same side as the inferior vena cava (IVC). The Fontan procedure is a common operation for ACJ patients, and possible surgical options include ipsilateral, contralateral, and lateral-tunnel conduits. Concerns about these surgical options include inferior hemodynamic performance or risks of compression by the cardiac mass. Unfortunately, little information is available in the previous literature. This study conducted a computational analysis on nine ACJ patients to assess fluid mechanics and explore possible surgical improvements.
Nine consecutive ACJ patients are included. An additional nine patients without ACJ were included as a reference cohort. Cardiac magnetic resonance (CMR) and phase-contrast CMR data were obtained for all patients, and computational simulations were performed to assess clinically important hemodynamic metrics including indexed power loss (iPL) and hepatic flow distribution deviation from 50% (HFDoff). The deformation index (DI) of the conduits were obtained to assess the risks of compression by cardiac mass. Additionally, a “virtual” surgery was performed in SURGEM III by implanting a straight lateral-tunnel conduit. This procedure was performed for three ipsilateral patients and three contralateral patients. Hemodynamic differences were investigated between original and straightened conduits.
The DI for ACJ is 19.3%±3.6%, which is in the DI range of non-ACJ patients (16% to 28%). The iPL for contralateral conduits (0.070±0.058) is higher than that for ipsilateral conduits (0.04±0.033) and non-ACJ conduits (0.034±0.015), but was not statistically significant. The HFDoff show no significant difference between ipsilateral, contralateral, and non-ACJ Fontan conduits (21±8%, 26±85, and 18±15%, respectively). Moreover, in the “virtual” surgery, the straight conduit reduced HFDoff (3±1%) and iPL (3±2%) from the ipsilateral conduits. The straight conduit also reduced HFDoff (5±1%) and iPL (21±14%) when compared to the contralateral conduits.
These findings indicate that the current three surgical options for ACJ patients are equivalent in terms of iPL and HFDoff. However, the contralateral conduits are prone to worse energy efficiency, although it is not statistically significant. Moreover, this study shows that the ipsilateral conduits are not at risk of compression by the cardiac mass, which is a previous concern regarding this type of conduit. Therefore, it is suggested that the ipsilateral lateral-tunnel conduits are preferable for future ACJ patients in terms of hemodynamic performance. Nevertheless, superiority of a conduit should not only consider the hemodynamic performance of the conduit but also feasibility of surgical implementations and associated complications.