Abstract Body (Do not enter title and authors here):
Background: The single ventricular (SV) palliative strategy involves routing the caval blood flow into the pulmonary arterial circulation. The superior cavopulmonary connection (SCPC) and Fontan connection generally raises caval pressures, although the changes to caval flows in SV patients has not been investigated. In this study, we determined the effect of SCPC and Fontan operation by comparing caval flows in SV pediatric patients against patients with biventricular (BiV) circulation as determined by 4D flow cardiac MRI (CMR).
Methods: Clinically indicated CMR of two hundred and thirty-eight pediatric patients (≤18 years of age) were retrospectively analyzed. All included studies had ferumoxytol-enhanced 4D flow (Seimens 1.5T). Patients with systemic/pulmonary venous abnormalities were excluded. Flow in the superior vena cava (SVC) was measured by an independent observer using cloud-based platform Arterys (Figure 1A). The SVC flow was indexed against body surface area or expressed as a ratio of total venous return. Unpaired T-test and correlation analysis was used to compare differences between BiV and SV patients.
Results: The cohort consisted of 149 BiV and 89 SV patients (8.5±5.7 years, body surface area 1.1±0.5 m², 99 female). The indexed SVC flow negatively correlated with age (r=-0.313, p<0.0001) and body surface area (r=-0.540, p <0.0001). SVC flow as a ratio of total venous return was also negatively correlated with age (r=-0.332, p<0.0001) and body surface area (r=-0.546, p<0.0001-Figure 1B). SV patients post-SCPC had associated lower SVC flow compared to BiV children (1.3±0.6 vs. 1.6±0.7 L/min/m², p<0.0001-Figure 1C).
Conclusion: The caval flow distribution in the pediatric population changes with age and body size. SV patients with an SCPC had associated lower SVC flow compared to BiV patients. Determining the general caval flow distribution provides insight into the evolving flow hemodynamics of the growing pediatric patient, which in turn could be used to optimize the cavopulmonary connection in SV patients.