Both atria communicate with the ventricle by a single atrio-ventricular valve.

There is a big shunt left-right with a quickly evolutive pulmonary hypertension.

Infants born with DILV cannot feed normally (breathlessness) and have difficulty gaining weight.

The mixed blood in systemic circulation leads to hypoxia (lack of oxygen to the body and organs), so infants develop cyanosis and breathlessness early.

Diagnosis must be made within few days or even hours to prevent death.