Supramitral ring is a type of congenital MS which is supposed to have better prognosis than the other types. It is thought to be derived from failure of the endocardial cushions to divide completely. The ring, which is fibrous, can be complete or partial, maybe annular or supra-annular and maybe associated with normal or abnormal mitral valve [1].
Cor triatriatum sinister is a rare anomaly due to incomplete incorporation of the pulmonary vein into the LA [2]. It results in the formation of two chambers of LA, the posterosuperior chamber which receives blood from pulmonary veins and the anteroinferior chamber which contains the LAA and mitral valve orifice. The size of the opening in the membrane classifies cor triatriatum into three types. Type 1 has no opening, where the accessory left atrium drains into the right heart, type 2 has a small opening, and type 3 has a large opening with little or no obstruction. Types 1 and 2 present in childhood due to obstruction in pulmonary venous return with pulmonary hypertension, while most patients with type 3 are asymptomatic in childhood [2, 3].
Echocardiography is the first-line choice for the evaluation of pulmonary venous anomalies, but it lacks the ability to 3-dimensionally display the pulmonary veins and their relationships to the left atrium. Computed tomography angiography (CTA) is the modality of choice for the diagnosis of pulmonary venous anomalies. It noninvasively and accurately evaluates the presence, course, and number of anomalous veins; associated cardiovascular defects; and any other lung or vascular anomaly with detailed anatomical assessment. It allows rapid acquisition of data with high spatial resolution and wide anatomic coverage. Thus, it is considered superior to echocardiogram and cardiac catheterization. Magnetic resonance imaging (MRI) is an excellent imaging modality for anomalous pulmonary veins. White blood imaging sequences do not always provide sufficient spatial resolution for the more peripheral pulmonary veins, especially when the anatomy is complex. Contrast MRA and time-resolved MRA allow proper visualization of the pulmonary veins; however, it takes a long time. Phase contrast MRI may have a role in evaluation of flow pattern within pulmonary veins. Digital subtraction angiography is a criterion-standard method for assessment of complex congenital heart disease in infants and children, but it is an invasive procedure with high radiation doses [2].
To the best of our knowledge, simultaneous presence of supramitral ring and cor triatriatum has not been described in the literature. Simultaneous presence of both entities in our patient, resulting in formation of four chambers of atria, justifies the term “cor tetratriatum”.
Unroofed coronary sinus is a rare congenital heart defect where the wall of the coronary sinus is partially or completely absent. It is classified according to the Kirklin and Barratt-Boyes classification into four types depending on whether the unroofing is complete or partial, and whether associated with PLSVC or not. The type I defect, completely unroofed CS with PLSVC, is called Raghib syndrome. Though this defect can be made out with TTE/TEE, a better imaging modality is bubble contrast TTE/TEE, where contrast injected in left arm vein results in opacification of LA followed by RA. These findings can be confirmed by cardiac MRI, cardiac CT, and cardiac catheterization [4].
There are few reports on the simultaneous presence of cor triatriatum and Raghib syndrome. It results in the PLSVC draining into lower chamber of LA which communicates with LAA and with RA through the ASD. It predominantly results in right to left shunt, resulting in cyanosis [5].
In our patient, there were two right to left shunts: from PLSVC to LA2 via unroofed coronary sinus and from RA to LA2 through the ASD due to the severe PAH, resulting in cyanosis and clubbing. As both the membranes in the LA were non-obstructive, there was delayed presentation of the patient in the fifth decade of life. Though there was presence of PLSVC with completely unroofed CS and definite right to left shunt from PLSVC to LA2 since birth, presence of associated supramitral ring diverted most of the systemic venous blood entering the middle LA chamber to the RA through the ASD; hence, our patient probably had no history of visible cyanosis before. However, once he developed Eisenmenger syndrome, he developed the second right to left shunt through the ASD resulting in visible cyanosis and clubbing.