Congenital heart defects: When your baby's born with a heart malformation

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Congenital heart defects: When your baby's born with a heart malformation

Eight out of 1,000 babies are born with structural flaws in their hearts — congenital heart defects. Surgery can correct all but the most severe.

If your infant or child has been diagnosed with a congenital heart defect, it means he or she was born with a problem in the heart's formation. You're likely to be anxious and worried about your child's immediate and long-term future. Knowing how the heart develops can help you understand your child's condition and what to expect in the coming months.

Some defects are as simple as a small hole between heart chambers that closes on its own. Others are a complex misconfiguration of blood vessels that require phased surgery over time.

How the heart works

The heart is divided into four hollow chambers, two on the right and two on the left. In performing its basic job — pumping blood throughout the body — the heart uses its left and right sides for different tasks. The right side of the heart moves blood to the lungs through vessels called pulmonary arteries. In the lungs, blood picks up oxygen then returns to the heart's left side through the pulmonary veins. The left side of the heart then pumps the blood through the aorta and out to the body.

How heart defects develop

A baby's heart starts beating just 22 days after conception. At that point, the heart has a simple tube shape. Between days 22 and 24, the heart begins to bend to the right and fold in on itself to form a loop. By 28 days after conception, the tube has a vaguely heart-like shape with structures corresponding to the heart's two sides and the large blood vessels that carry blood in and out of them.

You may not even realize you are pregnant when these important changes are occurring. But if there are errors in the genetic messages that direct the growth and movement of early heart cells, part of the heart muscle may fail to develop. If the process of bending and looping doesn't go exactly the way it's supposed to, the heart may form abnormal connections to the large vessels leading to and from the lungs.

Signs of trouble

Many heart defects can be detected before birth by a test called fetal echocardiography. In this test, sound waves are used to create a picture of your baby's heart. Doctors can use the information from the ultrasound test to diagnose the condition and plan treatment.

Serious heart defects usually become evident during the first few days, weeks and months of life. Your baby's skin may lose its healthy color and look pale gray or blue. Swelling may develop in the legs, abdomen or areas around the eyes. Perhaps your baby has shortness of breath during feedings, which leads to poor weight gain. Although other conditions can cause such signs and symptoms, they may indicate a congenital heart defect.

In all, there are more than 35 common congenital heart defects, falling mainly into these categories:

  • Holes in the heart. Several defects can be thought of as holes in the walls between heart chambers or abnormal passageways between major blood vessels leaving the heart. These holes allow oxygen-rich and oxygen-poor blood to mix. If the holes are large and a lot of blood is mixed, the blood that ends up being circulated through your baby's body is not carrying as much oxygen as normal. Poorly oxygenated blood causes your baby's skin or fingernails to appear slightly bluish in color. Your baby may also develop signs and symptoms of congestive heart failure, such as shortness of breath, lethargy and leg swelling, because both oxygen-rich and oxygen-poor blood are flooding (overcirculating) the lungs.

    Examples of hole defects include ventricular septal defect, which is a hole in the wall between the right and left ventricles; atrial septal defect, a hole between the upper heart chambers; and patent ductus arteriosus (DUK-tus ahr-teer-e-O-sus), an opening between the pulmonary artery and the aorta. During fetal development, this opening allows blood in the fetus to bypass the lungs. Within a few hours after birth, however, it should close. If it doesn't, oxygen-rich blood intended for the body is directed back to the lungs.

  • Obstructed blood flow. When vessels or valves become narrowed, the heart must work harder to push blood through them. Among the most common obstructive defects is pulmonary stenosis (stuh-NO-sis), a narrowing of the pulmonary valve, through which blood passes from the right ventricle to the pulmonary artery. Another obstructive defect, aortic stenosis, is a narrowing of the aortic valve, through which blood passes from the left ventricle into the aorta. The narrowed valve forces the heart muscle to work harder, eventually leading to thickening and enlarging of the muscle.
  • Abnormal blood vessels. Several congenital heart defects involve incorrectly formed or positioned blood vessels going to and from the heart. For example, transposition of the great arteries occurs when the pulmonary artery and the aorta are on the wrong sides of the heart. This is a serious and immediately life-threatening defect.
  • Heart valve abnormalities. If the heart valves can't open and close correctly, blood can't flow smoothly. Examples include Ebstein's anomaly, in which the tricuspid valve is malformed and often leaks, and pulmonary atresia, in which a solid sheet of tissue forms in place of the pulmonary valve and blocks normal blood flow to the lungs. Both defects prevent oxygen-poor blood from circulating to the lungs.
  • A combination of defects. Some infants are born with several heart defects. For example, tetralogy of Fallot is a combination of four defects: a hole in the ventricular septum; a narrowed passage between the right ventricle and pulmonary artery; a shift in the connection of the aorta to the heart; and thickened muscle in the right ventricle.

Underlying causes unclear

Most congenital heart defects arise from errors early in the heart's development, the cause of which is unknown. However, it is known that certain environmental and genetic risk factors may play a role. They include:

  • Rubella (German measles). Having rubella during pregnancy can cause errors in fetal heart development. Your doctor can test you for immunity to this viral disease before pregnancy and vaccinate you against it if you aren't immune. You should wait at least 28 days after being vaccinated before attempting to conceive.
  • Diabetes. Having this chronic condition can interfere with the development of the fetus's heart. You can reduce or eliminate the risk by carefully controlling your diabetes before attempting to conceive and during pregnancy.
  • Medications. Taking certain medications while pregnant is known to cause birth defects. Give your doctor a complete list of the medications you take before attempting to become pregnant. Medications that increase risk include the acne drug isotretinoin (Accutane) and lithium (Eskalith), which is used to treat bipolar disorder, a condition that causes intense mood swings. Also avoid alcohol during pregnancy because babies with fetal alcohol syndrome often have congenital heart defects.
  • Heredity. Congenital heart defects appear to run in families and are associated with many genetic syndromes. More than one-third of children with Down syndrome — which is caused by an extra 21st chromosome (trisomy 21) — have heart defects. A missing piece (deletion) of genetic material on chromosome 22 also causes heart defects. Genetic testing can detect such disorders during fetal development. Researchers have identified several genes critical for the proper development of the heart. If you already have a child with a congenital heart defect, a genetic counselor can predict the approximate odds that your next child will have one.

Treatment of congenital heart defects

Depending on the type of heart defect, doctors treat congenital heart defects with:

  • Medicine
  • Special procedures using catheters
  • Surgery
  • Heart transplants

Some congenital heart defects can be treated with medications that help the heart work more efficiently. In more severe cases, however, surgical repair is needed.

Many children and adults now have their congenital heart defects repaired using catheterization techniques, which allow the repair to be done without surgically opening the chest and heart. In procedures that can be done using catheterization, the doctor inserts a thin tube (catheter) into a leg vein and guides it to the heart with the help of X-ray images. Once the catheter is positioned at the site of the defect, tiny tools are threaded through the catheter to the heart to repair the defect. Until recently, an atrial septal defect — a hole between the heart's upper two chambers — could be treated with only open-heart surgery. Today, such a hole is usually closed with an expandable disk positioned in the heart using a catheter.

If a serious heart defect can't be repaired, a heart transplant may be an option.

The outlook: Generally good

Thanks to treatment advances, the odds are improving even for infants with multiple, serious congenital heart defects. For example, tetralogy of Fallot, once considered fatal, is now usually repairable. Some children with congenital heart disease will require multiple procedures and surgeries throughout life. Although the outcome has improved dramatically, most people, except those with very simple defects, will require lifelong medical care, even after corrective surgery.

A congenital heart defect may have no long-term effect on your child's health — in some instances, such defects can safely go untreated. Sometimes they aren't even discovered until adulthood.

On the other hand, a severe congenital heart defect such as hypoplastic left heart syndrome, in which the left side of the heart is too small to support life, may be fatal shortly after birth. If a child with a severe and complicated heart defect survives infancy, he or she may require close medical supervision and repeated surgical procedures that may eventually include a heart transplant.

Parents of children with congenital heart defects may worry about the risks of rough play and vigorous activity even after successful treatment. Although some children may need to limit the amount or type of exercise, many can participate in normal or near-normal activity. Your doctor can advise you about which activities are safe for your child. If some activities do pose special dangers, encourage your child in other pursuits instead of focusing on what he or she can't do. Although every circumstance is different, remember that most children with congenital heart defects grow up to lead healthy, productive lives.

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