In this type of defect, the valve between right atrium and right ventricle has not developed properly and therefore there is obstruction of blood flow from right atrium to ventricle. Instead blood flows through inter Atrial Septal Defect to left atrium causing mixture of impure blood with pure blood. As a result the baby becomes blue. Also the right ventricle remains underdeveloped or rudimentary.

• Bluish discoloration of skin

• Shortness of breath

• Clubbing of finger

• Easy fatigability

This condition may be discovered during routine pre- natal ultrasound. Detailed echocardiography after birth will pick up the diagnosis.

Approach vary depending  on the severity of the defect but usually a series of operation is required. In very childhood if the cyanosis becomes severe, a systemic to pulmonary artery shunt may be necessary. Definitive treatment is Fontam  operation which involves diversion of venous blood from upper and lower part of the body to the pulmonary circulation there by bypassing the right side of the ventricle. Usually this operation is done in two stages. Initially the superior vena cava is diverted followed by the inferior vena cava. The major problem after this operation is increased systemic venous pressure leading to fluid collection in all body cavities especially inside the chest and abdomen. As a long term complication, these patients may loose protein through the gut and may develop abnormal connection between arteries and veins inside the lung (arteriovenous fistula).