Cor triatriatum may exist as a stand alone abnormality [1], or may be associated with other congenital heart malformations, some caused by absent or abnormal conotruncal inversion, some by persistence of embryonic structures, some by lack of atrial, ventricular or atrioventricular septum development [2]. Some associations, such as between cor triatriatum and a bicuspid aortic valve, may be harder to explain as a consequence of a single event in embryonic development and may occur as separate entities [3]. Other left heart obstructive lesions may also exist [4].

The patient presents for various reasons, depending on heart anatomy and function. If the abnormality is left- sided, symptoms are similar to those induced by mitral stenosis, appear sooner and are more dramatic if the opening in the accessory membrane separating the true left atrium from the supranumerary chamber is smaller. If this communication is large, the patient may be asymptomatic and diagnosis is made on an echocardiography examination performed for other reasons. If complaints do exist, they consist of hemoptysis, orthopnea and signs of left heart failure: dyspnea on exercise and asthenia. Children with a restrictive membrane defect fail to thrive or may present with severe neonatal respiratory distress [5] due to the pressure gradient between the true and accessory atrial chambers. In cor triatriatum dexter, right heart failure signs appear first and consist of edema, ascites, painful hepatomegaly and jaundice. Rhythm abnormalities like atrial fibrillation or tachycardia may coexist in both forms. Physical examination of a cor triatriatum sinister patient may reveal further abnormalities: signs of systemic embolism, pulmonary rales or pleural effusion, heart murmurs, tachypnea and respiratory distress. In a right sided abnormality, the physician may find elevated jugular venous pressure, tricuspid regurgitation and right ventricular heave. Pulmonary hypertension may also be present. Adults become symptomatic if the membrane within the left atrium becomes calcified [6] or during sustained effort, such as labor [7] [8].

Hypoxemia may be noticed in a newborn with severe respiratory distress caused by cor triatriatum. The electrocardiogram may be normal or it may show signs of right ventricular hypertrophy and strain, right axis deviation, left, right or biatrial enlargement and supraventricular arrhythmia. Thoracic radiography may reveal pulmonary congestion and pleural effusion and cardiomegaly due to enlarged atria and dilated pulmonary arteries. Heart catheterization shows increased left atrial, right atrial, ventricular and pulmonary artery pressures, that become worse during exercise [9], with possible systemic hypotension and a gradient across the accessory membrane. Cardiac computer tomography and magnetic resonance are used when diagnosis is uncertain [10], but echocardiography usually elucidates the diagnosis [11], the morphology of the atria and venous return and the hemodynamic consequences of the abnormality. If a restrictive opening in the accessory membrane exists, the flow across it will be found both during the systole and diastole [12]. Three dimensional fully-sampled matrix array transoesophageal echocardiography (TEE) offers further information, if needed [13].

Treatment for Cor Triatriatum depends on the severity of symptoms and the degree of obstruction. In symptomatic cases, surgical intervention is often required to remove the membrane and restore normal blood flow. This is typically done through open-heart surgery. In some cases, minimally invasive techniques may be used. Asymptomatic patients with mild obstruction may be monitored regularly without immediate intervention.

The prognosis for individuals with Cor Triatriatum is generally good, especially when the condition is diagnosed and treated early. Surgical removal of the membrane usually results in significant improvement of symptoms and normal heart function. However, if left untreated, severe cases can lead to complications such as pulmonary hypertension (high blood pressure in the lungs) and heart failure.

Cor Triatriatum is a congenital condition, meaning it is present at birth. It results from an abnormal development of the heart during fetal growth. The exact cause of this abnormal development is not well understood, and it is not typically associated with genetic syndromes or familial patterns. Environmental factors during pregnancy have not been definitively linked to the condition.

Cor Triatriatum is a rare condition, accounting for less than 0.1% of all congenital heart defects. It occurs equally in males and females and can be diagnosed at any age, though it is often identified in infancy or early childhood due to the presence of symptoms. In some cases, it may remain undiagnosed until adulthood.

In Cor Triatriatum, the heart's atrium is divided by a fibromuscular membrane, creating two chambers instead of one. This division can impede the normal flow of blood from the atrium to the ventricle, leading to increased pressure in the atrium and pulmonary veins. Over time, this can cause enlargement of the atrium and increased pressure in the lungs, potentially leading to pulmonary hypertension and heart failure.

Currently, there are no known measures to prevent Cor Triatriatum, as it is a congenital defect with unclear etiology. Prenatal care and regular monitoring during pregnancy can help in the early detection of congenital heart defects, allowing for timely intervention after birth.

Cor Triatriatum is a rare congenital heart defect characterized by an abnormal membrane in the atrium, leading to potential obstruction of blood flow. Symptoms can range from mild to severe, and diagnosis is primarily achieved through imaging studies. Treatment often involves surgical removal of the membrane, with a generally favorable prognosis when addressed early. The condition's exact cause remains unknown, and it is not preventable.

For patients and families, understanding Cor Triatriatum can be challenging due to its rarity. It is important to know that this condition is present from birth and can vary in severity. If diagnosed, treatment options are available, and surgical intervention can significantly improve symptoms and quality of life. Regular follow-up with a cardiologist is essential to monitor heart function and manage any potential complications.

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