In this defect, pulmonary blood flow (through the pulmonary artery to the lungs) is excessive. Affected infants usually cannot feed normally, and usually have difficulty gaining weight.  They may be only mildy cyanotic.

In some patients, there is mild obstruction to either systemic or pulmonary blood flow. Blood flow through the aorta to the body may become restricted if the size of the ventricular septal defect is too small, resulting in serious illness. (The only route of blood flow to the aorta is across the ventricular septal defect.) Medications may help if there are signs of heart failure, and there are surgical procedures that improve the balance of blood flow.

(Opposite)
1. Rudimentary right ventricle
2. Ventricular septal defect (VSD)
3. Transposition of the great arteries
4. Double inlet left ventricle
5. Atrial septal defect (ASD)
6. Ventricular inversion (position of ventricles reversed from normal)
7. Left aortic arch (compare to normal position)