Unroofed Coronary Sinus

Unroofed Coronary Sinus

Unroofed coronary sinus is a rare congenital cardiac anomaly which might be difficult to diagnose. It is classified as an atrial septal defect and constitutes the rarest form of this group of congenital heart disease. Persistent LSVC occurs in 0.1 to 0.5% of the general population, with 8% draining into the left atrium. Unroofed coronary sinus defect is seen in over 70% of patients with a LSVC that drains into the left atrium. It should be suspected in patients with persistent LSVC and a history of paradoxical embolism or brain abscess. Coronary sinus defect has been reported to occur with other congenital heart diseases, such as cor triatriatum, pulmonary atresia, tetralogy of Fallot and anomalous pulmonary venous drainage.

The anatomic abnormality is variable and classified into four groups: type 1, completely unroofed with persistent LSVC; type 2, completely unroofed without persistent LSVC; type 3, partially unroofed mid portion; and type 4, partially unroofed terminal portion. The presented case appears to be consistent with type 4 subgroup of this anomaly.

The development of symptoms appears to be related to the size of the defect, and the severity of the inter-atrial shunt, which may lead to the development of right heart failure. The diagnosis should be suspected in a patient with LSVC and associated brain abscess or cerebral emboli; or in a patient with unexplained arterial oxygen desaturation. Management depends on the clinical symptoms and surgical intervention should be considered when the symptoms cannot be managed medically. Imaging plays a crucial role in the diagnosis. Transthoracic echocardiography is, limited in its ability to evaluate the posterior structures. Cross sectional imaging with computed tomography (CT) and magnetic resonance imaging Are well suited to identify this abnormality.

What is the clinical relevance of this entity?

This entity should be suspected in every patient with persistent LSVC, (and LSVC should be suspected in every patient with ASD). The hemodynamics is that of an ASD but if sufficient mixing of LSVC blood and LA blood takes place the child will have mild cyanosis. Some times when the coronary sinus is totally absent it will present as a typical dusky ASD picture which can closely mimic a TAPVC clinically.