Congenital Heart Disease
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An article from
Hygeia Foundation Inc.
Vol.1 No.6
Text ©opyright
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By Joshua A. Copel, M.D.
Director of Maternal and Fetal Medicine
Department of Obstetrics and Gynecology
The Yale University School of Medicine
Congenital heart disease is one of the most common congenital anomalies. Overall approximately 3% of newborns are found to have some major congenital anomaly, and about one in 6 of these have congenital heart disease. Looked at another way, about 30,000 infants die annually in the US between 5 months pregnancy and one year after birth. One in five die because of congenital anomalies, and one third of these are cardiovascular abnormalities.
The origin of cardiac abnormalities lies in the complex development of the heart. Starting out as a single, straight hollow tube, the heart must divide into two sides, and fold over on itself twice to begin to reach its final form. Some areas must differentiate into electrical conduction tissues, and others to muscle, while still others must develop into the strong tissues of the valves that keep blood moving in the proper direction. When one considers the incredible complexity of this process it becomes easier to understand that there are many ways in which it can develop abnormally. The most common fetal cardiac abnormalities are: Complete atrioventricular septal defect "canal" defect, Hypoplastic left heart syndrome,and Double outlet right ventricle/tetralogy of Fallot. Other abnormalities are all much less common than these three (the third involves a spectrum of abnormalities that are all related etiologically). In newborns the most common defect is ventricular septal defect.
Newborns with congenital heart disease usually look pretty similar to unaffected newborns for the first few hours after birth. Before birth the heart is specially adapted for intrauterine life. The fetus does not breathe inside the womb, rather the placenta does the breathing work for the fetus. Normally there are connections between the right and left sided receiving chambers of the heart (the atria), and between the two main arteries that leave the heart, the aorta to the body and the pulmonary artery to the lungs.
Newborns with many types of severe heart problems do well until these normal connections begin their normal process of closing. At that point, fetuses with absence of one of the normal pumping chambers, the ventricles, for example, will begin to show the abnormal coloration or labored breathing that are often the first signs of cardiac abnormalities. These signs are similar to those seen in newborns with infections and some other problems, so it may take a couple of hours for the recognition that a heart problem is present. Especially in these days of early hospital discharges for apparently healthy moms and babies, problems may not arise until the child has been brought home. For new parents of a first child, even recognizing that there is a problem can take a while. Figure: A Normal Fetal Heart
Certain groups of pregnant women have been identified as being at special risk of delivering a baby with a heart abnormality. Women who have had a prior child with heart disease have a 2-3% risk of having another (1 in 30-50). If mom herself was born with a heart abnormality the risk may be as high as 5% (1 in 20). Some medications, such as those used to control epilepsy, can damage the developing heart, but are still important for women to take for their own health. Recently, high doses of Vitamin A, 10,000 units a day or more, have been identified as causing a high risk of fetal heart abnormalities. Oral contraceptives and fertility medications, such as ClomidŽ, and PergonalŽ, fortunately appear to be safe.
It is also fortunate that testing is available for pregnancies identified as being at high risk of fetal heart abnormalities. The test, called a fetal echocardiogram, uses the same ultrasound technology that is used for measuring the fetus and taking pictures of other parts of the fetus. In a fetal echocardiogram the entire heart is systematically examined for normal development. Any areas of suspected abnormality can be evaluated in detail, often by using special ultrasound techniques that measure the direction and speed of blood as it flows through the heart, called Doppler ultrasound. Fetal echocardiograms should be performed by physicians with special expertise in the examination of the fetal heart. These may be obstetricians, pediatric cardiologists, or radiologists, usually working in a team effort. Suspected abnormalities are generally referred to regional or supra-regional centers with extensive experience in evaluating the test.
What if a fetal heart abnormality is found? The first step is to perform a thorough examination of the rest of the fetal anatomy, to be sure that no other abnormalities are present that might complicate caring for the newborn. Next comes consultation witha pediatric cardiologist to discuss what might need to be done for the newborn. This usually includes discussion of delivery at a pediatric heart center that can operate on the baby if needed. It is especially important psychologically for the parents to be near the baby if at all possible. The possible operations that may need to be done are discussed, and the long term outlook for the baby can be outlined. If the pregnancy is early enough, and the long term outlook bleak, many families do choose to terminate the pregnancies, an unpleasant alternative to be sure in what are always wanted pregnancies, but an important choice to include in discussions with the parents. Delivery is usually vaginal, there is no evidence that cardiac babies do better if delivered by cesarean section.
Being prepared with knowledge of the presence of a heart abnormality, the pediatric team can plan for the delivery. We find it helpful for the parents to meet with the hospital neonatal intensive care specialists beforehand, and to get a tour of the nursery to familiarize themselves as much as possible with where their baby will be, and the people who will be taking care of their baby.
Heart Info & Anatomy Diagrams
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