[Surgical experience of two different types of unroofed coronary sinus]

We experienced two cases with uncommon unroofed coronary sinus. The first patient, a 55-year-old man, had a partially unroofed mid-portion of the coronary sinus. His symptoms and physical state were similar to that of atrial septal defect (ASD). Echocardiogram and angiogram revealed that the coronary sinus (CS) communicated with the left atrium (LA). We confirmed that CS had an enlarged orifice and lacked a part of its roof through the right atriotomy and the atrioseptotomy. We directly closed the defect between the LA and the CS. His postoperative course was satisfactory. The second patient, a 46-year-old man, showed mild cyanosis. He had a completely unroofed CS with left superior vena cava (LSVC), absent inferior vena cava (IVC) and hemiazygos continuity. The LSVC directly drained to the LA, and the CS was absent. A part of the posterior wall of the LA was like a groove which laid from the orifice of the LSVC to the coronary sinus ASD. The roof of this groove was covered with fibrous tissue, which was shaped like a network structure. We thought that this network was a residue of the septum between the CS and the LA. Thus we resected this structure, and reconstructed the roof by equine pericardial patch to drain the venous blood from the LSVC to the right atrium. Anomaly in the patient may be the transitional type between the completely unroofed CS and the partially unroofed CS.