A female with five chambers

This case depicts the classical sequela of intravenous drug abuse in the form of right-sided valve endocarditis. Transoesophageal echocardiography (TEE) shows a vegetation of 0.8 cm on the posterior tricuspid leaflet and severe tricuspid regurgitation with jet velocity of 34 mm Hg (Fig. 1). Also, there was an incidental detection of prominent eustachian valve extending all towards the interatrial septum in right atrium consistent with diagnosis of cor triatriatum dexter (Fig. 1; Video loop 1 and 2). Blood cultures were positive for methicillin-susceptible S. aureus for which treatment was initiated with intravenous cefazolin.

Cor triatriatum is a rare congenital cardiac abnormality in which either the right (dexter) or the left (sinister) atrium gets divided into two compartments resulting in a tri-atrial heart. The sinister variant is more common than the dexter.

Cor triatriatum dexter is the result of persistence of right valve of sinus venosus. The septum is formed as a result of fusion of the eustachian and thebesian valve. It has varying presentations from being asymptomatic to florid right-sided heart failure depending upon the degree of partition of the right atrium. Important to note that cor triatriatum dexter is more than just a membrane and has important clinical implications such as its association with dilated right atrium which is a risk for thrombus formation or arrythmia formation [1]. In most cases, cor triatriatum is detected in infancy due to either heart failure, pulmonary oedema or cyanosis that often requires correction [2]. Very rarely it might be detected in adults incidentally as in our case. Awareness of the rare cardiac entities is essential for timely diagnosis and intervention [3, 4, 5].