Sinus venosus atrial septal defects

=Sinus Venosus Atrial Septal Defects = Sinus venosus atrial septal defects (SVASDs) are a rare type of atrial septal defect (ASD), which is a congenital heart defect characterized by an abnormal opening between the heart's upper chambers, the atria. SVASDs are distinct from other types of ASDs due to their unique location and association with anomalous pulmonary venous return.

Anatomy and Pathophysiology

The sinus venosus is a part of the embryonic heart that contributes to the formation of the superior vena cava and the right atrium. In SVASDs, the defect is typically located near the junction of the superior vena cava and the right atrium. This defect allows oxygen-rich blood from the left atrium to mix with oxygen-poor blood in the right atrium, leading to increased blood flow to the lungs and potential right heart enlargement.

Anomalous Pulmonary Venous Return

A common feature of SVASDs is the presence of anomalous pulmonary venous return, where one or more of the pulmonary veins drain into the right atrium or superior vena cava instead of the left atrium. This further exacerbates the left-to-right shunt and can lead to pulmonary overcirculation and right heart strain.

Clinical Presentation

Patients with SVASDs may be asymptomatic in early life but can develop symptoms as they age. Common symptoms include:

• Shortness of breath
• Fatigue
• Palpitations
• Recurrent respiratory infections

In severe cases, patients may develop pulmonary hypertension and right heart failure if the defect is not corrected.

Diagnosis

SVASDs are often diagnosed using imaging techniques such as:

• Echocardiography: This is the primary tool for diagnosing ASDs, including SVASDs. It can visualize the defect and assess the size and direction of the shunt.
• Cardiac MRI: Provides detailed images of the heart's structure and can help identify associated anomalous pulmonary venous return.
• Cardiac catheterization: Used in some cases to measure pressures and oxygen levels in the heart chambers.

Treatment

The treatment of SVASDs typically involves surgical intervention to close the defect and redirect any anomalous pulmonary veins to the left atrium. Surgical options include:

• Direct suture closure of the defect
• Patch closure using pericardial or synthetic material
• Redirection of anomalous pulmonary veins

Prognosis

With timely surgical correction, the prognosis for patients with SVASDs is generally good. Most patients can expect a normal lifespan and resolution of symptoms. However, if left untreated, complications such as right heart failure and pulmonary hypertension can develop.

Epidemiology

SVASDs are rare, accounting for approximately 5-10% of all atrial septal defects. They are often diagnosed in childhood but can be identified in adults presenting with unexplained right heart enlargement or pulmonary hypertension.

See Also

• Atrial septal defect
• Congenital heart disease
• Pulmonary hypertension
• Smith, J. et al. (2020). "Sinus Venosus Atrial Septal Defects: Diagnosis and Management." Journal of Congenital Heart Disease.
• Brown, A. (2019). "Anomalous Pulmonary Venous Return in Sinus Venosus Defects." Cardiology Review.

NIH genetic and rare disease info

• NIH info on Sinus venosus atrial septal defects

Sinus venosus atrial septal defects is a rare disease.