Congenital Heart Defects

Congenital Heart DefectsAbout 40,000 infants (1 out of every 125) are born with heart defects each year in the United States. The defect may be so slight that the baby appears healthy for many years after birth, or so severe that its life is in immediate danger.
Heart defects are among the most common birth defects and are the leading cause of birth defect-related deaths. However, advances in diagnosis and surgical treatment have led to dramatic increases in survival for children with serious heart defects.

What is a congenital heart defect?
A condition is called congenital when it is present at birth. Heart defects originate in the early part of pregnancy when the heart is forming. Congenital heart defects can affect any of the parts or functions of the heart.

How does the heart work?
The heart is a muscle that pumps blood to the body. It is divided into four hollow parts called chambers. Two chambers are located on the right side of the heart, and two are on the left.

Within the heart are four valves (one-way openings) that let the blood go forward and keep it from going back. Blood goes from the heart to the lungs where it picks up oxygen. The blood carrying oxygen, which appears bright red, goes back to the heart. The heart then pumps the oxygen-rich blood through the body by way of arteries. As the body's tissues and organs use up the oxygen, the blood becomes dark and returns by way of veins to the heart, where the process starts over again.

How do heart defects affect a child?
Some babies and children with heart defects experience no symptoms. The heart defect may be diagnosed if the health care provider hears an abnormal sound, referred to as a murmur. Children with normal hearts also can have heart murmurs. These are called innocent or functional murmurs. A provider may suggest tests to rule out a heart defect.
Certain heart defects prevent the heart from pumping adequate blood to the lungs or other parts of the body. This can cause congestive heart failure (inability of the heart to pump out all the blood that returns to it, leading to fluid build-up in the heart, lungs and other parts of the body). An affected child may experience a rapid heartbeat and breathing difficulties, especially during exercise. Infants may experience these difficulties during feeding, sometimes resulting in inadequate weight gain. Affected infants and children also may have swelling of the legs or abdomen or around the eyes.
Some heart defects result in a pale grayish or bluish coloring of the skin called cyanosis. This usually appears soon after birth or during infancy. On occasion, cyanosis may be delayed until later in childhood. It is a sign of defects that prevent the blood from getting enough oxygen. Children with cyanosis may tire easily. Symptoms, such as shortness of breath and fainting, often worsen when the child exerts himself. Some youngsters may squat frequently to ease their shortness of breath.

What tests are used to diagnose heart defects?
Babies and children who are suspected of having a heart defect are usually referred to a pediatric cardiologist (children’s heart disease specialist). This doctor will do a physical examination and often recommend one or more tests. These tests often include a chest X-ray, an electrocardiogram (which records heart rate patterns) and an echocardiogram (a special form of ultrasound that uses sound waves to take pictures of the heart). All of these tests are painless and non-invasive (nothing enters the child’s body). Some children with heart disease also may need to undergo a procedure called cardiac catheterization. In this procedure, a thin, flexible tube is inserted into the heart after the child is given medications to make him sleepy. This test provides detailed information about the heart and how it is working.

What causes congenital heart defects?
In most cases, scientists do not know what makes a baby's heart develop abnormally. Both environmental and genetic factors appear to play roles.
A few environmental factors are known to contribute to congenital heart defects. Women who contract rubella (German measles) during the first three months of pregnancy have a high risk of having a baby with a heart defect. Other viral infections also may contribute, as may exposure to certain industrial chemicals (solvents). Drinking alcohol in pregnancy also can increase the risk of heart defects, as may cocaine.
Certain medications increase the risk. These include the acne medication isotretinoin (Accutane and other brand names), lithium (used to treat certain forms of mental illness) and certain anti-seizure medications.
Certain chronic illnesses in the mother may contribute to the risk. For example, women with diabetes are at increased risk of having a baby with a heart defect. However, women with diabetes can reduce their risk by seeing their health care provider before pregnancy to make sure their blood sugar levels are well controlled. Women with an inherited error of body chemistry called phenylketonuria (PKU) also are at high risk of having an affected baby, unless they follow a special diet before and during pregnancy. Some studies suggest that women who do not consume enough of the B vitamin folic acid before and during the early weeks of pregnancy may be at increased risk of having a baby with a heart defect.
Scientists are making progress in understanding the genetics of heart defects. Since the 1990s, they have identified several gene mutations (changes) that can cause heart defects. For example, a March of Dimes grantee discovered a series of genetic steps that appears to contribute to a common, important group of malformations affecting the heart’s outflow tract. He also identified a gene that can cause a heart defect called an atrial septal defect (a hole between the upper chambers of the heart) and one that may contribute to hypoplastic left heart syndrome (underdevelopment of the heart’s main pumping chamber).
Heart defects also can be part of a wider pattern of birth defects. For example, about one-half of children with the chromosomal abnormalities Down syndrome (mental retardation and physical birth defects) and Turner syndrome (short stature and lack of sexual development) have heart defects. Children with Down syndrome, Turner syndrome and certain other chromosomal abnormalities should be routinely evaluated for heart defects. Heart defects also are common in children with a variety of inherited disorders, including Noonan (short stature, learning disabilities), velocardiofacial (craniofacial defects and immune deficiencies), and Holt-Oram (limb defects) syndromes.

What are some of the most common heart defects and how are they treated?
Patent ductus arteriosus. Before birth, a large artery (ductus arteriosus) lets the blood bypass the lungs because the fetus gets its oxygen through the placenta. The ductus normally closes soon after birth so that blood can travel to the lungs and pick up oxygen. If it doesn’t close, the baby may develop heart failure. This problem occurs most frequently in premature babies. Drug treatment often can close the ductus. If that doesn't work, surgery can close it.

Septal defect. This is a hole in the wall (septum) that divides the right and left sides of the heart. A hole in the wall between the heart’s two upper chambers is called an atrial septal defect, while a hole between the lower chambers is called a ventricular septal defect. These defects can cause the blood to circulate improperly, so the heart has to work too hard. A surgeon can close the hole by sewing or patching it. Small holes may heal by themselves or not need repair at all.
Coarctation of the aorta. Part of the aorta, the large artery that sends blood from the heart to the rest of the body, may be too narrow for the blood to flow evenly. A surgeon can cut away the narrow part and sew the open ends together, replace the constricted section with man-made material, or patch it with part of a blood vessel taken from elsewhere in the body. Sometimes, this narrowed area can be widened by inflating a balloon on the tip of a catheter (tube) inserted through an artery.
Heart valve abnormalities. Some babies are born with heart valves that do not close normally or are narrowed or blocked, so blood can’t flow smoothly. Surgeons usually can repair the valves or replace them with man-made ones. Balloons on catheters also are frequently used to fix faulty valves.
Tetralogy of Fallot. This combination of four heart defects keeps some blood from getting to the lungs. As a result, the blood that is pumped to the body may not have enough oxygen. Affected babies have episodes of cyanosis and may grow poorly. This defect is usually surgically repaired at around 3 to 6 months of age. Most affected children live normal or near-normal lives.
Transposition of the great arteries. Transposition occurs when the positions of the two major arteries leaving the heart are reversed, so that each arises from the wrong pumping chamber. Affected newborns suffer from severe cyanosis due to a lack of oxygen in the blood. Recent surgical advances make it possible to correct this otherwise lethal defect in the newborn period.
Hypoplastic left heart syndrome. This combination of defects results in a left ventricle (the heart’s main pumping chamber) that is too small to support life. This defect is the most common cause of death from congenital heart disease. However, over the past 20 years, survival rates have dramatically improved with new surgical procedures and, less frequently, heart transplants. The long-term outlook for children with this heart defect remains uncertain.

Due to advances in treatment of heart defects, about 1 million children and adults in the United States with heart defects are alive today. Many children who require surgical repair of heart defects now undergo surgery before age 1. Until recently, it often was necessary to make temporary repairs and postpone corrective surgery until later in childhood. Early corrective surgery often prevents development of additional complications and allows the child to live a more normal life sooner.
Children and adults with certain heart defects, even after surgical repair, remain at increased risk of infection involving the heart and its valves. Parents of children with heart defects and adults with repaired heart defects should discuss with their provider whether they need to take antibiotics before certain dental and surgical procedures in order to prevent these infections.

Is there a prenatal test for congenital heart defects?
Echocardiography can be used before birth to accurately identify many heart defects. If this test shows that a fetus’s heart is beating too fast or too slowly (called an arrhythmia), the mother can be treated with medications that may restore a normal heart rhythm in the fetus. This treatment often prevents fetal heart failure. In other cases, where the heart defect can't be treated before birth, parents and providers can plan the delivery so that the baby can receive necessary treatment soon after birth.

Can congenital heart defects be prevented?
Most congenital heart defects cannot be prevented. However, there are some steps a woman can take that may help reduce her risk of having a baby with a heart defect. A woman should be tested before pregnancy for immunity to rubella and vaccinated if she is not immune. Pregnant women should avoid alcohol and unprescribed drugs. Those with chronic health conditions, such as diabetes, seizure disorders and PKU, should consult their providers before they attempt to conceive so that their medications and/or diets can be adjusted. Any woman who could become pregnant should take a multivitamin containing 400 micrograms of folic acid daily to reduce the risk of serious birth defects of the brain and spinal cord and, possibly, heart defects.

Are heart defects likely to recur in another pregnancy?
Parents who have already had a child with a heart defect do have an increased risk of having other affected children, often with the same heart defect. In many cases, the risk is low. Some heart defects have about a 2 to 3 percent chance of happening again. However, the risk differs slightly, depending on the specific heart defect. If a child’s heart defect is part of a syndrome of other birth defects, the recurrence risk in another pregnancy may be much higher.
Parents who have had a child with a heart defect can consult a genetic counselor to find out the risks to any future children. Parents who themselves have a heart defect also are at increased risk of having an affected child and should consider consulting a genetic counselor.

Is pregnancy safe for women with heart defects?
Many women with congenital heart defects can safely become pregnant and deliver healthy babies. However, women with congenital heart defects always should check with their cardiologist before they become pregnant. Pregnancy can be risky for women with certain types of heart disease (including those with poorly functioning ventricles or high blood pressure in the lungs). In some cases, the mother’s heart disease or the medications she takes to treat it can affect the fetus, causing poor growth or other problems. Some women with heart disease may need careful monitoring by a high-risk obstetrician, as well as their cardiologist, throughout pregnancy.