ADVANCES IN INFANT HEART SURGERY
Commentary by Dr. Kathleen N. Fenton

Because open-heart surgery is now fairly commonplace, we often forget that it is a relatively new specialty. The first "open" heart operations were done less than 50 years ago. These were all operations for congenital heart disease. The first valve replacements were reported in 1961, and the first coronary bypass operations were done in the United States in the late 1960s. Heart surgery has rapidly advanced in the subsequent decades.

The development of the heart and great vessels before and after birth is partly dependent upon blood flow patterns. Abnormal blood flow patterns can cause too little growth or too much growth of the heart chambers and valves.

Too much blood flow to the lungs causes an increase in the muscle of the pulmonary arteries, and ultimately causes irreversible damage. In some cases this can occur within the first year of postnatal life. Survival of newborns with some severe congenital heart defects depends on the maintenance of the fetal circulatory pattern which provides blood flow to both the body and lungs. In the past, most infants with these defects died shortly after birth, when the fetal pattern is disrupted. Now, administration of prostaglandin can temporarily maintain the fetal circulatory pattern until surgery can be done.

Until recently, it was not possible to perform open-heart surgery in young infants; today, neonatal heart surgery could almost be called commonplace. Our improved ability to treat small infants with heart defects can be attributed to a range of clinical advances.

Some "technical" advances have come from a close cooperation between surgeons and engineers: the heart-lung machine has been refined so that it is now smaller and safer. Instruments and sutures are smaller. New suture materials are stronger and cause less tissue reaction. Some suture material is absorbable, which may allow better growth of blood vessels. Surgeons routinely use magnifying glasses.

Other advances made by our colleagues in cardiology, such as improved angiograms before surgery and echocardiograms before and during surgery have allowed more accurate diagnoses to be made (often even before the baby is born) and have permitted an assessment of our repairs before we even leave the operating room.

Fetal echocardiography: normal fetal study (left) and hypoplastic left heart (right).

Neonatal and pediatric intensive care units provide expert preoperative and postoperative management of critically-ill infants, and the new specialty of pediatric anesthesiology provides expert care in the operating room. The availability of prostaglandin, used to keep the ductus arteriosus open after birth, allows newborns with severe heart defects such as pulmonary atresia and hypoplastic left heart syndrome to survive long enough to have surgery.

Advances in many fields now work together to allow us to perform complex surgery in the first days of life.

Our goals are first to save the child's life, then to allow optimal growth and development of the heart, great vessels, lungs, and brain. Infants with congenital defects that require neonatal repair are critically ill, but earlier operation often allows improved results, as has recently been reported for truncus arteriosus (Figures 1 and 2), a defect in which a single large blood vessel from the heart supplies both the body and lungs, causing too much blood flow to the lungs, with early development of pulmonary vascular disease.

Fig. 1. Improved survival related to earlier repair of truncus arteriosus in infants.

Fig. 2. Decreasing age at time of repair of truncus arteriosus over past years.

In the coming years, we will see further improvements in the results of neonatal heart surgery, especially for complex defects that require multiple palliative operations. The recent ability to treat some defects in the cardiac catheterization lab will be beneficial to many patients.

It is our hope that the increasing availability and accuracy of prenatal echocardiography will contribute to better preoperative management and better long-term outcomes, and that this diagnostic technology may one day allow intervention before birth, so that we can save the lives of even more children.