Congenital Heart Defects

Congenital heart defects (congenital heart disease) , refers to certain abnormalities in the structure of the heart or in the blood vessels around the heart. The heart of an infant in the womb normally begins to develop in the 5th week of pregnancy, and will be fully formed by around the 12th week. Genetic material known as genes is responsible for the construction of the infant's heart. Genes direct the action, order, and structure of the heart, and act as a blueprint for the rest of the body. A huge number of genes are required for the development of an infant's heart during pregnancy, and each of these genes must fit together correctly. If there is a defect in any one gene, or in any number of genes, then it may cause structural abnormalities to develop in the heart of an unborn child. At present, only a few defects in a small number of genes have been scientifically proven to cause congenital heart defects, and for the majority of patients, the doctor will be unable to identify the exact cause of the condition. The doctor will be aware, however, of certain factors which increase the risk of congenital heart defects in unborn children, by monitoring for such factors during pregnancy as the infant's heart develops.

Factors Which Increase the Risk of Congenital Heart Defects

1. Certain Types of Hereditary Conditions

  • Down syndrome develops when an infant has more than two copies of chromosome 21, which in turn causes delayed motor and cognitive development and lower than average IQ. Around 40 percent of children who have Down syndrome will also have heart defects.
  • Turner syndrome develops when an infant girl is born with only one X chromosome, leading to a shortness of height and absence of menstruation (infertility). Around 30 percent of girls who have Turner syndrome will also develop heart valve defects and constricted blood vessels around the heart. 

2. Risk Factors for Mothers During Pregnancy

  • Chronic conditions, such as diabetes. Women with diabetes who manage their blood sugar level poorly during pregnancy will increase the risk of their child developing congenital heart defects. Common congenital heart defects caused by diabetes during pregnancy include Transposition of the Great Arteries (TGA), and a thickened heart muscle.
  • Illness during pregnancy, especially during the first trimester, can have an impact on the development of an infant's heart. If a pregnant mother is sick with German measles, for example, it may cause congenital heart defects in her child as well as defects in other organs such as the brain and eyes. If a pregnant mother is sick with influenza during pregnancy, this will double the risk of her child developing congenital heart defects. Therefore, during pregnancy the mother should make sure to look after her own health; and before pregnancy, the mother should get vaccinated for German measles and influenza (if she does not already have immunity). In addition, if the mother has a high fever during pregnancy, this can also cause congenital heart defects in her child. The mother should therefore take medication to reduce fever symptoms during pregnancy. Paracetamol is a safe medication to use for fever during pregnancy. However, a pregnant mother should not use other medications such as aspirin to reduce fever, as aspirin can cause heart defects in unborn children. Pregnant mothers should exercise caution, use as little medication as possible, and consult a doctor before taking any kind of medication during pregnancy.
  • Using medication or other drugs during pregnancy
  1. Use of alcohol or drugs during pregnancy may cause heart and other organ defects in the child in the womb, including brain defects. The severity of such defects will depend on the amount of drugs or alcohol the mother consumes during pregnancy. The best way to protect against such defects is for the mother to abstain from drinking alcohol and using narcotic drugs for the entire duration of her pregnancy.
  2. The mother should avoid using other drugs such as anticonvulsants, ibuprofen, and medication to treat spots or acne caused by vitamin A (retinol) deficiency, including both creams and tablets.
  3. The mother should also avoid coming into contact with certain types of chemicals, especially organic solvents used in paints, oil varnish, and nail polish.

The symptoms of congenital heart defects will depend on the type and severity of the heart defects present. In patients who have only mild congenital heart defects, there will usually be few symptoms or no symptoms at all. For patients who have more severe defects, however, the following symptoms may be observed:

  • Bluish tint of the skin, lips, fingernails, and inner lining of the mouth (cyanosis)
  • Rapid heartbeat
  • Rapid breathing / difficulty breathing
  • Becoming tired easily; decreased breast milk intake due to becoming tired easily
  • Not growing or gaining weight properly
  • Excessive sweating
  • Fatigue

By monitoring the child's development using ultrasound scans, some types of congenital heart defects can be diagnosed while the child is still in the womb. However, some defects may only be identified once the child is born, and often congenital heart defects may only be identified once the child has grown older or into an adult. If the doctor suspects that a child may have congenital heart defects, the doctor will conduct a physical examination of the child and may need to conduct further tests, such as those described below:

  • An echocardiogram, which uses ultrasound waves to examine the interior structure of the heart, the heart valves, and the function of the heart.
  • An electrocardiogram, which measures the electrical activity of the heart. It measures the amount of electricity and the time it takes for the electricity to pass through the heart so that doctor may be able to find out if parts of the heart are too large or are overworked.
  • chest X-ray, which examines the size and the position of the heart, as well as the condition of the blood vessels which supply blood to the lungs.
  • Cardiac catheterization , which refers to the insertion of a small plastic tube (known as a catheter) into a large blood vessel, usually in the groin or the side of the neck. The catheter is then guided towards and enters the chambers of the heart, where it can measure the pressure and the level of oxygenated blood, in order to examine the functioning of the heart. Additionally, the doctor may also inject a special dye (known as contrast medium) into the heart in order to examine the functioning of the heart utilizing X-ray movies.
  • An MRI scan, which examines the structure of the heart and creates 3-D images of the heart using a magnetic field and pulses of radio wave energy.
  • A CT scan, which examines the structure of the heart using an X-ray computer.
Congenital heart defect patients with only mild heart defects who have no symptoms and follow a normal growth pattern will normally not require treatment. However, patients who experience severe symptoms, such as a heart failure, shortness of breath, or becoming easily tired, will likely need to take medication to manage their symptoms. However, if the symptoms do not improve with treatment, then catheter intervention or heart surgery to correct the defects will be required. Certain types of defects, such as a hole in the heart wall can be treated using a heart catheterization so that an open heart surgery can be avoided. During the heart catheterization, a specially designed device can be mounted on the tip of a small plastic tube. This plastic tube can be inserted into a large blood vessel, usually from the groin, and sneaked into the heart to the site of the defect. Then, the device will be deployed to close off the defect.
  • Growth and development: Some factors related to congenital heart defects may interfere with a baby’s growth. These include rapid heartbeat, increased respiratory rate, poor appetite, and decreased food intake due to rapid breathing and fatigue. The most common reason for poor growth is that the baby does not take in enough calories and nutrients. But even if your baby seems to drink enough milk, he or she may still gain weight very slowly due to the increased caloric needs. A 250-450 gram gain in a month may be an acceptable weight gain for a baby with a heart defect.
  • Most children with congenital heart defects can attend school and fully participate. However, some children may have delays in development or learning difficulties. A child’s primary physician can make recommendations for testing and work with parents to find the right solution for the child.
  • Heart defects could lead to an increased risk of heart tissue infection (endocarditis). The mouth is a major source of germs that cause infection. Therefore, good oral hygiene is very important in preventing infection of the heart. Some children with congenital heart defects may need to take antibiotics before surgery or undergo dental procedures to prevent heart infection.
  • Some children with congenital heart defects require multiple procedures and surgeries throughout life. Even after corrective surgery, these children require ongoing care for the rest of their life.

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