Sinus Venosus Atrial Septal Defect

Sinus venosus atrial septal defect accounts for about 5–10% of all ASDs and is located in the upper posterior atrial septum near the entry of the superior vena cava into the right atrium. It is frequently associated with anomalous drainage of the right upper pulmonary vein into the superior vena cava (partial anomalous pulmonary venous return).

The defect may remain silent for years; depending on the size of the left-to-right shunt, right heart enlargement and pulmonary hypertension can develop. Reduced exercise capacity, palpitations and atrial arrhythmias may emerge later.

Transthoracic echocardiography is often insufficient; the diagnosis is confirmed with transesophageal echocardiography, cardiac CT or MRI. Treatment is surgical: closure with a pericardial patch and rerouting of the anomalous pulmonary veins.