New surgery for severe heart defects in infants shows promise

A new surgery could help averting heart transplants in infants born with poorly developed hearts.

The new surgical procedure is likely to make infants born with congenital heart disease survive their first year and not require a heart transplant than those who have a more traditional surgical procedure, according to a report.

Congenital heart disease is the most common birth defect. Every year, about 1 per cent of babies are born with abnormally formed hearts.

The normal heart has two pumping chambers called ventricles. The right ventricle pumps blood to the lungs, and the left ventricle pumps blood to the body.

Sometimes babies are born with a severe form of congenital heart disease in which they will have a functioning right ventricle and a small, underdeveloped, nonfunctioning left ventricle.

The condition is sometimes referred to as hypoplastic left heart syndrome.

Without treatment, these babies usually die shortly after birth.

Usually, three surgeries are needed to treat a single right ventricle.

The first procedure, called the Norwood procedure, is usually performed within the first two weeks of life and is one of the highest risk procedures in congenital heart surgery.

A shunt, or small tube, is implanted to provide a connection for blood to flow from the heart to the blood vessels in the lungs, or pulmonary arteries, so that blood can pick up oxygen and release carbon dioxide.

Children later undergo a second surgery at four to six months of age, and a third procedure, known as the Fontan procedure, at 18 to 36 months.

The operations are staged to allow the child to grow large enough that the corrective procedures can be performed. Heart transplantation may be required for children with single ventricles when surgery and other treatments fail.

In the new study, researchers supported by the National Heart, Lung, and Blood Institute (NHLBI), which is part of the National Institutes of Health, analysed data from 549 newborns.

Called the Single Ventricle Reconstruction (SVR) Trial, it is the largest clinical trial to compare treatments for congenital heart disease, and the first North American, multi-center, randomized trial of surgical therapy for congenital heart disease patients.

When SVR Trial compared the two surgical procedures that are commonly used to treat babies born with only the functioning right ventricle to determine whether one procedure improves outcomes more than the other.

Participants were randomly assigned shortly after birth to receive one of two types of shunts for their initial surgery, as part of the Norwood procedure.

About half of the newborn participants received a modified Blalock-Taussig (MBT) shunt, the traditional approach, which places the shunt from a branch off of the aorta, the major blood vessel that takes blood from the heart to the rest of the body, to the pulmonary artery.

The other participants received a newer type of shunt, called an RVPA shunt, which is placed between the right ventricle and the pulmonary arteries.

Each type of shunt has advantages and disadvantages. A few small studies of the RVPA shunt have suggested that it provides better survival and other outcomes than the MBT shunt.

Researchers followed all study patients for at least 14 months. They evaluated the number of deaths and heart transplantations in each group at one year, as well as the number of complications linked to each type of shunt.

“We found that the right ventricle-to-pulmonary artery shunt improved the chances of being alive without a heart transplant one year after surgery,” stated Richard G Ohye, head, Paediatric Cardiovascular Surgery Division, University of Michigan, Ann Arbor, and lead author of the study.

However, the benefit appears to be limited to the first 12 months, as the two shunts showed similar results after about two years.

After 12 months, 74 per cent of infants with the RVPA shunt survived and didn’t need a heart transplant, compared to 64 per cent of infants with the MBT shunt.