In the first eight weeks after conception, the fetal heart changes from a kind of primitive, coiled tube into a complex, functioning organ. Many things can go wrong in this process. The partitions between the heart's chambers may fail to develop properly, leaving abnormal connections between the two sides of the heart, or the valves connecting the chambers may be displaced, narrowed or completely closed. Blood-vessel abnormalities may occur as well. Finally, the baby's heart and circulatory system may fail to make the necessary adaptations to life outside the womb.
Malformations such as these are known as congenital heart defects, and they occur in about eight of every one thousand babies born. Over 35 specific congenital heart defects have been identified; for descriptions of the most common defects, see the accompanying chart. Some of these abnormalities may not be noticed until late infancy or even early childhood.
WHAT CAUSES CONGENITAL HEART DEFECTS?
In 90 percent of cases, no cause can yet be identified. Heredity plays a role; a child whose parent (especially the mother) has a congenital heart defect stands a slightly increased chance of a cardiac abnormality. Certain congenital heart defects tend to occur as part of well-identified chromosomal abnormalities such as Down's syndrome. A small percentage of cases stem from infections such as rubella (German measles) the mother contracted during pregnancy. The mother's use of alcohol during pregnancy also is associated with congenital heart defects, as is the use of medications to control epilepsy. These defects also occur in greater than expected number among babies whose mothers have diabetes or are over 40.
The vast majority of congenital heart defects are thought to stem from a combination of genetic and environmental factors.
WHEN SHOULD I SUSPECT THAT MY CHILD HAS A CONGENITAL HEART DEFECT?
In about one-third of cases, a heart defect is apparent to the pediatrician and newborn-care nurses in the hospital shortly after birth. Some cases are identified by a fetal electrocardiogram as early as the fourth month of pregnancy. Such babies may have bluish skin caused by oxygen deprivation, abnormal heart sounds, or congestive heart failure, a condition caused by the heart's inability to pump enough blood to meet the body's needs.
After the baby is home from the hospital, feeding problems, fatigue, irritability and poor weight gain become apparent. In toddlers, poor appetite, short stature, lower weight, decreased energy and frequent respiratory infections are common.
HOW CAN THE PEDIATRICIAN TELL IF MY CHILD HAS A HEART DEFECT?
During regular checkups, the pediatrician looks for signs that suggest heart defects. If anything suggests heart disease, a visit with a pediatric heart specialist (cardiolgist) is in order. Often, a heart murmur is the finding that leads to a consultation.
WHAT TREATMENTS ARE AVAILABLE?
The treatment depends on the type of defect. A small hole in the wall between the heart's lower chambers (known medically as a ventricular septal defect or VSD) may close by itself without treatment. A slightly narrowed heart valve may cause no symptoms except a heart murmur and thus require no treatment.
More severe defects (such as a large ventricular septal defect) are usually corrected with surgery. The operation may be postponed until the second or third month of life—or, in some cases, even later.
The majority of complicated heart defects require open-heart surgery. Fortunately, most of these operations have a high success rate, often bringing immediate and dramatic improvements in the child's condition. In addition, new surgical procedures that do not require opening the heart are currently being developed.
Medication may be needed until the child undergoes surgery. Children with heart defects are at high risk of developing endocarditis (an infection of the heart lining), so they need antibiotics before having dental work or any type of operation. Even after corrective surgery, preventive use of antibiotics is still advisable.
DIAGNOSING HEART DEFECTS
A technique called two dimensional echo cardiography is used to diagnose most heart defects. This test, which is similar to ultrasound, produces a cross-sectional image of the heart, and provides information about the pattern and rate of blood flow within the heart. In some instances, echocardiography has been used successfully to diagnose fetal heart defects before birth.
Doctors in a few medical centers are also experimenting with magnetic resonance imaging (MRI)—a technique that converts radio waves from chemicals in the body into computer generated images of tissues—to evaluate some types of heart defects.
In complex cases, cardiac catheterization is necessary. After contrast dyes are injected into the heart's circulation through a catheter, the cardiologist takes still and moving X-ray pictures of blood as it passes through the heart. Such information is often essential for planning corrective surgery.
COMMON CONGENITAL HEART DEFECTS
• Ventricular Septal Defect: Abnormal opening between the two lower chambers
• Patent Ductus Arteriosus: The passage through which blood bypasses the lungs during fetal development fails to close after birth
• Persistent Truncus Arteriosus: Coronary, pulmonary and systemic arteries all arise from a single artery at the base of the heart
• Pulmonary Stenosis: Narrowing of the opening of the artery that carries blood from the heart to the lungs
• Atrial Septal Defect: Abnormal opening between the two upper chambers
• Coarctation of the Aorta: Narrowing of the aorta, the large vessel that carries blood from the heart to the body
• Aortic Stenosis: Narrowing of the valve between the lower left heart chamber of the aorta
• Tertralogy of Fallot: Four associated defects: a ventricular septal defect; pulmonary stenosis; displaced aorta; and enlargement of the lower right chamber
• Transposition of the Great Arteries: Displacement of the aorta and pulmonary arteries so that each originates on the wrong side of the heart
GETTING HELP
Call your doctor if:
A child with a congenital heart defect develops signs of congestive heart failure, which includes:
• Rapid breathing
• Coughing
• Wheezing
• Sweating
• Fatigue
• Restlessness
• Flaring nostrils
• Spaces between ribs drawing inward
• Fluid buildup (swollen hands and ankles and a puffy face)
