label: Unroofed coronary sinus
label_lc: unroofed coronary sinus
description: "Unroofed coronary sinus (CS) is a rare congenital cardiac anomaly in which there is partial (either focal or fenestrated) or complete absence of the roof of the CS, which results in a communication between the CS and the LA. Unroofed CS is the rarest type of atrial septal defect. It is often associated with persistent left superior vena cava (LSVC) and other forms of complex congenital heart disease, usually heterotaxia syndromes. The morphological types have been classified into 4 groups: Type I, completely unroofed with persistent LSVC; type II, completely unroofed without persistent LSVC; type III, partially unroofed mid portion; and type IV, partially unroofed terminal portion."