Quantitative analysis of extracardiac versus intraatrial Fontan anatomic geometries.

Background: There exists large geometric variability among total cavopulmonary connections (TCPC) because of the patient-specific anatomies and the chosen surgical procedure. In this study we present quantitative comparison of the geometric characteristics of the extracardiac and intraatrial Fontan anatomies, the two commonly used TCPC procedures.

Methods: A method of centerline approximation of the three-dimensional geometries (skeletonization) was used to quantify the TCPC geometric parameters such as vessel areas, curvature, and collinearity. The TCPC anatomies of 26 patients, 13 extracardiac and 13 intraatrial, were analyzed in this study.

Results: There was no significant difference in the vessel dimensions between extracardiac and intraatrial TCPCs, with the overall magnitudes agreeing well with that seen in normal children except for the inferior vena cava. Intraatrial baffles had significant fluctuations in cross-sectional area along the length of the baffle as opposed to extracardiacs (p < 0.05). Patients with hypoplastic left heart syndrome had significant narrowing of the left pulmonary artery (p < 0.05), suggesting a possible physical constriction from the reconstructed aorta.

Conclusions: This study benchmarks the anatomic variability of patient-specific TCPCs. Intraatrial Fontan geometries have significant difference in the area variations across the vessel length compared with the extracardiac geometry. Also, patients with hypoplastic left heart are at a higher risk of left pulmonary artery narrowing.