Superior sinus venosus defect (SVD) is a complex congenital heart disease (CHD) with a wide spectrum of anatomical variations. The innovative procedure of transcatheter SVD correction (TCSVD) is feasible in selected cases, highlighting the need for a detailed morphological understanding. This study aims to provide an anatomical classification of SVD using 3D models.

Cardiac computed tomography (CT) scans with superior SVD were 3D-modeled using semi-automatic segmentation. Key parameters such as superior vena cava (SVC) size, SVC overriding, caudal defect extension, and the size/orientation of anomalous pulmonary vein return (APVR) were analyzed in this single center cohort study.

A total of 197 patients with superior SVD were studied. SVC overriding was absent in 38% of cases, and >50% in 7%. A single anomalous pulmonary vein ostium was identified in 52%, while additional ostia were observed in 48%. Among children >12 years, 83% had a SVC diameter larger than 14mm (first quartile of adult population). SVD were classified in two types: Fenestration (30%) and Cavo-atrial (70%), based on overriding degree and defect extension (Fig. 1). Associated lesions included left superior vena cava (15%) and ostium secundum atrial septal defect (8%).

3D segmentation of a large cohort of SVD provides a new accurate and simplified anatomical description and classification, enabling tailored strategies for TCSVD.