What is cor triatriatum dextrum?

Cor Triatriatum Dextrum

Cor triatriatum dextrum is a rare congenital cardiac anomaly in which a fibromuscular membrane divides the right atrium into two chambers, potentially causing obstruction to blood flow and various clinical manifestations depending on the degree of partitioning. 1, 2

Definition and Anatomy

Cor triatriatum dextrum (CTD) is characterized by:

• A membranous structure that divides the right atrium into two chambers 3
• Results from the persistence of the right valve of the sinus venosus, which normally regresses during embryological development 3
• Creates a separation between:
  • A smooth posterior chamber that receives venous blood from the inferior vena cava, superior vena cava, and coronary sinus
  • A trabeculated anterior chamber containing the right atrial appendage and the opening of the tricuspid valve 4

Clinical Presentation

The clinical manifestations of cor triatriatum dextrum vary based on:

• The degree of partitioning or septation of the right atrium 3
• The size of the opening in the membrane
• The presence of associated congenital anomalies

Common presentations include:

• Cyanosis, particularly in neonates and children 5, 4
• Palpitations due to enlarged right atrium 2
• Heart failure symptoms
• May be asymptomatic and discovered incidentally 3

Associated Anomalies

CTD is frequently associated with other congenital cardiac defects:

• Atrial septal defect (ASD) 6, 5
• Other right-sided congenital heart abnormalities 3

Diagnosis

Echocardiography is the primary diagnostic tool for cor triatriatum dextrum:

• Transthoracic echocardiography can identify the membrane dividing the right atrium 3
• Transesophageal echocardiography may provide better visualization in some cases 5
• Bubble contrast studies can help confirm the diagnosis by demonstrating flow patterns 4

Treatment

Management depends on the severity of obstruction and associated symptoms:

• Surgical excision of the membrane is the definitive treatment for symptomatic patients 2, 4
• In cases with associated defects like ASD, comprehensive surgical repair is recommended 6
• Percutaneous treatment may be considered in select cases with incomplete membrane and favorable anatomy 6
• Right atrial reduction may be necessary in cases with giant right atrium 2

Prognosis and Follow-up

• Surgical outcomes are generally favorable with complete resolution of symptoms 2, 4
• Patients should be evaluated for other congenital abnormalities
• Long-term follow-up with echocardiography is recommended to monitor for any recurrence or development of complications

Clinical Pitfalls and Considerations

• CTD can be easily missed on routine echocardiography if not specifically looked for
• The condition should be considered in the differential diagnosis of unexplained cyanosis, especially in neonates 5, 4
• Distinguishing CTD from other right atrial pathologies such as tumors, thrombi, or prominent Eustachian valve is important
• In patients with incomplete membrane and favorable anatomy, percutaneous treatment can be considered, but surgical repair remains the gold standard for complex cases 6

The diagnosis requires careful echocardiographic assessment, and management should be guided by symptom severity and associated anomalies.