The outlook has never been brighter for babies and children with congenital heart defects. Today, most heart defects can be corrected, or at least helped, by surgery, medicine or mechanical aids such as pacemakers. In the last 25 years, advances in treatment of heart defects have enabled half a million children with significant heart defects to survive into adulthood. Half the children who require surgical repair of a heart defect now undergo surgery before age 2. Until fairly recently, it was often necessary to make temporary repairs and postpone corrective surgery until later in childhood. Early corrective surgery often prevents development of additional complications and allows the child to live a more normal life sooner.

Here are some of the most common defects and their treatment:

Patent ductus arteriosus

While a fetus is in the womb, much of its blood goes through a passageway (ductus arteriosus) from one blood vessel to another instead of to the lungs, because the lungs are not yet in use. The passageway should close soon after birth, so the blood can take the normal route from heart to lungs and back. If it doesn't close, blood doesn't flow correctly. This problem occurs most frequently in premature babies. In some cases, a drug can close the passageway. If that doesn't work, a surgeon can close it.

Septal defects

If the defect is a hole in the wall (septum) that divides the two upper or two lower chambers, the blood can't circulate as it should and the heart has to work too hard. A surgeon can close the hole by sewing or patching it. Small holes may heal by themselves or not need repair at all.

Coarctation of the aorta

Part of the aorta, the large artery that sends blood from the heart to the rest of the body, may be narrow so that the blood can't flow evenly. A surgeon can cut away the narrow part and sew the open ends together, or patch over the constricted section with man-made material or a blood vessel taken from elsewhere in the body. Sometimes this narrowed area can be widened by inflating a balloon on the tip of a catheter inserted in an artery and surgery can be avoided.

Heart valve abnormalities

Some babies are born with heart valves that are narrowed, closed or blocked and prevent blood from moving along smoothly. Surgeons can repair the valves or replace them with man-made ones. Balloons on catheters are frequently of use here as well, making surgery unnecessary.

Tetralogy of Fallot

A combination of four heart defects keeps some blood from getting to the lungs for oxygen, and the baby becomes blue and sickly. New surgical techniques allow early repair of this complex heart defect, so that most affected children live normal or near-normal lives.

Transposition of the great arteries

Here, the two major arteries leaving the heart are transposed. They each arise from the wrong pumping chamber. Recent surgical advances have resulted in correction of this otherwise lethal defect in the early newborn period.