Abstract
Cor triatriatum is an uncommon cardiac defect that occurs in 0.1-0.4% of congenital heart disease patients. It is characterized by a fibromuscular membrane separating the left (sinister) or the right (Dexter) atriums in tow chambers. The disease is usually discovered accidently in late childhood, usually as a result of a moderate form of this condition type. We discuss the case of a 14-year-old girl who had been experiencing exertional dyspnea and palpitations for about a year. She was referred to our hospital for assessment after an initial echocardiogram at another hospital revealed a mass around the left atrium. Repeated echocardiography at our institution revealed dilated coronary sinus, confusing the diagnosis. The left atrium was dilated and divided into 2 chambers by a thin membrane with an elevated pressure gradient between the 2 chambers. Cardiac CT and MRI confirmed the diagnosis of cor triatriatum sinister (CTS) with concomitant persisting left superior vena cava. Because of her symptoms, she was started medical treatment and referred for surgical evaluation. Cor triatriatum sinister (CTS) is frequently accompanied with atrial septal abnormalities and enlarged coronary sinus caused by a persistent left superior vena cava, as demonstrated in our case. The management of cor triatriatum sinister (CTS) is determined by the severity of the symptoms. Asymptomatic individuals with no pressure gradient do not require therapy; however, significant membrane obstruction may require surgical removal, which typically leads to positive short- and long-term outcomes.