A Brief History…

When the infant is delivered into the world from its mother’s uterus, it inflates its lungs and very rapidly major circulatory changes occur in the heart and lungs. The pulmonary arteries to the lungs, which during intrauterine life carry almost no blood because of a very high resistance to flow in the collapsed lungs, suddenly become a low resistance circuit with the inflation. The foramen ovale, which has a flap valve as a part of its normal structure, begins to close very quickly and the ductus arteriosus, connecting the pulmonary artery and the aorta, also closes within a matter of several hours. These two shunt closures are accomplished by hormonal changes associated with the changing physiology of the newborn. In very low birth weight preemies, that have low blood oxygen concentration due to immature lungs, the ductus often does not close. In the child with a ventricular septal defect, the sudden drop in resistance to flow in the pulmonary circulation together with the closing of the ductus arteriosus causes the shunt, which was directed from the right to the left heart in utero, to switch to a left to right shunt after birth. The pulmonary circulation is now the low resistance circuit and the systemic circulation; that is, the aorta going out to the arms, legs, and organs is now a relatively high resistance circuit. The flow in the pulmonary circuit goes up tremendously, a short circuit in effect, taxing the ability of the right ventricle to handle the load. At the same time circulation to the organs, the brain and the extremities, drops because of the shunt. This combination of circumstances produces acute congestive heart failure in a newborn. Cardiac output is huge but the flow is going around in a circle through the lungs and then back to the lungs.

Chris had a huge ventricular septal defect and as soon as his lungs inflated and the pulmonary circulation began to assume the normal low resistance of the newborn, he developed an enormous left to right shunt and went into heart failure. The venous return from the body entered his right atrium, passed into the right ventricle and on into the pulmonary artery to circulate through the lungs. Once the oxygenated blood returned to the left atrium on its way to the body, it was shunted back to the lungs because the pressure in the aorta and left ventricle was much higher than that in the right ventricle and pulmonary artery. The short circuit in the heart diverted almost all blood flow to the lungs and little went to the body. The right ventricle, which is thin walled and flat like a wallet, cannot handle the load and quickly fails. The treatment of an infant with a large ventricular septal defect and heart failure is to perform a temporary correction by placing a band around the pulmonary artery above the heart. This accomplishes two purposes. One, it artificially creates a high resistance and equalizes the pressure in the right and left ventricles so that the flow across the ventricular septal defect is minimized. The right ventricular pressure is as high as the left ventricular pressure and little or no shunt occurs. This stops the huge shunt and, with the smaller flow, the ventricle can handle the pressure. It also protects the lungs from high blood flow that damages the pulmonary circulation.

In a related anomaly called “Tetralogy of Fallot” a partial shunt occurs but it is the other way, right to left, since the pulmonary artery is severely narrowed at its origin as part of the anomaly. These children do not go into heart failure, but they are blue because of the mixture of venous blood from the right side and arterial blood from the left. Some patients with ventricular septal defect (VSD) do not go into heart failure because the shunt is not that large but if treatment is delayed and a continued high flow through the lungs persists, in later life they develop irreversible changes in the lungs from the damage to the pulmonary circulation by high flow rates. They become blue later as the increasing pulmonary resistance in the lungs reverses the shunt from left to right to right to left as in Tetrology of Fallot. This condition is called “Eisenmenger’s Complex” and, once it occurs, cannot be corrected. Once this reversal occurs they do not benefit from correction and require heart and lung transplantation. Some VSDs are small and do not produce enough flow to cause trouble, at least in childhood.

Chris had a pulmonary artery banding procedure at about two or three days of life and an extremely stormy course for a very long time postop. He was in the Intensive Care Unit at Children’s Hospital for over a year. He had a tracheostomy for much of that time as he was unable to breathe without a respirator for a year. He had intravenous feeding for well over a year. During this time he had several cardiac arrests and the staff became convinced that he would be brain damaged if he survived. Finally, after 18 months in Children’s Hospital, he went home. This had all occurred before my time. Now, 3 years later, he was being admitted for the definitive repair of his heart defect. The pulmonary band is Teflon tape and does not grow so the pulmonary stenosis, which had saved his life, was now a threat, as it did not permit adequate flow to his growing lungs. He was five years old and was joyously normal. His intellectual development, in spite of everything, was normal and he was a very calm and self-confident little kid. He was not afraid of the hospital or of us, the white coat brigade. Most nurses and staff in children’s hospitals and pediatric clinics avoid white coats preferring colorful smocks to reassure kids that we are all regular folks. The kids are not fooled but it does seem to defuse the tension, especially at first. When we would make rounds on the ward for the few days Chris was in the hospital for pre-op checks, he would go around with us. He wore his little bathrobe and sometimes carried charts for us. He was completely unafraid. I don’t know if it was because he remembered his previous experience; I didn’t think that memory would be very reassuring.

Anyway, the day of surgery came. His mother was a nervous wreck because she had come so close to losing him and here they were risking him again. I did not see much of the family on the day of surgery. His grandfather was a famous movie star, one of the biggest box office leaders of all time, and the hospital had thrown a big luncheon bash for the family as they waited. We heard about it and grumbled that they could have spent the money on a better blood bank (we were having trouble getting blood for elective cases), but no doubt they hoped for a big donation. The surgery, itself, was almost an anticlimax. The data from the original heart cath, when he was a newborn, suggested that he had almost no interventricular septum and we anticipated trouble reconstructing a new septum. As it turned out, his heart, in its growth during the past five years, had developed a good septum with a modest sized defect in the usual place. It was easy to patch and the surgery went well. The other worry with VSDs is the conduction system, the Bundle of His, which carries the electrical stimulation to the ventricles, and runs right along the edge of the defect but this was not a problem. There was no sign of heart block after the sutures were placed and tied. Postop we always took the kids straight to the Heart Room, a combination recovery room and ICU. The nurses there knew more about cardiology than I did and probably more than anyone else at Children’s below the rank of associate professor. His mother came in and stood at his bedside for a while just thankful to have him. I never saw the rest of the family although I did meet his father before he went home. He recovered quickly and completely. I had one more encounter with him about a year later.