Triatrial heart

Triatrial heart (cor triatriatum) is a rare congenital cardiac malformation in which the left atrium (cor triatriatum sinistrum) or, much less commonly, the right atrium (cor triatriatum dexter) is divided into two chambers by an abnormal fibromuscular membrane or septum. The most common form, cor triatriatum sinistrum, accounts for approximately 0.1–0.4% of all congenital heart defects. In this condition, the pulmonary veins drain into a proximal accessory chamber, which communicates with the true left atrium through one or more openings in the dividing membrane. The degree of obstruction to pulmonary venous return determines the severity of symptoms and the age at presentation. When the membrane is significantly obstructive, patients may present in infancy or early childhood with symptoms resembling mitral stenosis, including pulmonary venous congestion, pulmonary hypertension, dyspnea, recurrent respiratory infections, failure to thrive, and heart failure. In cases with a large or non-restrictive opening in the membrane, patients may remain asymptomatic into adulthood and the condition may be discovered incidentally. Associated cardiac anomalies, such as atrial septal defect, anomalous pulmonary venous return, patent ductus arteriosus, or left superior vena cava, are found in a significant proportion of cases and may influence the clinical presentation. Diagnosis is typically established through echocardiography, which can visualize the intra-atrial membrane and assess the degree of obstruction. Cardiac catheterization, CT, or MRI may be used for further anatomical delineation. The definitive treatment is surgical excision of the obstructing membrane, which carries excellent outcomes with low operative mortality when performed at experienced centers. Long-term prognosis after successful surgical repair is generally very good, with most patients achieving normal cardiac function. Asymptomatic patients with non-obstructive membranes may be managed conservatively with regular follow-up.

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