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What is a congenital heart defect?

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The word congenital means ‘inborn or existing at birth.’ The phrases congenital heart defect and congenital heart disease are often used to mean the same thing, but the word defect is more accurate. Your heart disorder is an abnormality, not a disease. Your defect was caused by the incorrect development of the heart, or blood vessels near the heart, before birth.

How common are congenital heart defects?

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At least eight of every 1,000 infants born each year have a heart defect. That is almost one percent of live-born infants. Statistics Canada records tell us that 3,970 children with heart defects were born in this country in 1992. Surgery helps many children whose lives are endangered, or who are severely affected by their heart abnormality. Today it is estimated that some 200,000 Canadians have congenital heart defects.

What caused my congenital heart defect?

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It is often difficult to determine the cause of congenital heart disease. There is much yet to learn. Specialists believe that about ten percent of heart defects are caused by specific genetic abnormalities. These may result from abnormal chromosomes, as in Down’s syndrome, or from an abnormal gene that is passed down from one generation to the next, as in Marfan syndrome.

As for the remaining 90 percent, a poorly understood combination of genetic predisposition and environmental factors is thought to be responsible. Some congenital heart defects result from abnormalities in the mother’s health during pregnancy. Examples of these conditions are diabetes or systemic lupus erythematosus. Certain infections in the expectant mother may also cause abnormalities. For example, if a mother gets German measles (rubella) while pregnant, her baby has a significant risk of developing a heart defect (approximately 35 percent).

Certain drugs are felt to cause developmental heart abnormalities. This includes the mother’s use of alcohol, ‘street drugs’, and a number of prescription drugs such as seizure medications. Avoid unnecessary risks. Consult with your doctor before becoming pregnant.

Parents with congenital heart defects are more likely to have affected children than are parents with normal hearts (approximately ten percent versus one percent). Interestingly, the heart defect in your child may not be the same as yours. If one child in your family has a congenital heart defect, the chance of having other children with a heart defect is slightly increased (four percent versus one percent). Some heart abnormalities are more likely to be passed on than others. Your cardiologist or a doctor specializing in genetics can advise you if you have questions or concerns.

How is a congenital heart defect discovered?

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As a rule, a serious congenital heart defect is found in infancy. Often an a typical blue colour of the lips or an abnormal noise in the heart (murmur) suggests its presence. Life-threatening or very severe defects are often treated soon after birth with medication or surgery. However, defects that need treatment may be found anytime during childhood. Minor heart defects may not be discovered for many months or years. Your defect may not have been detected until you reached adulthood. If you have one of these conditions, you may require no medical intervention and have no limitations.

What happens after a heart defect is found?

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An electrocardiograph machine receives tiny electrical impulses from your heart and records them in a zigzag pattern on a moving strip of paper. The impulses are sent through small round discs (electrodes) that are attached to your chest and limbs. The discs are connected to the electrocardiograph machine by cables called leads. A  graph of the heartbeat is called an electrocardiogram. A cardiologist looking at an ECG learns about your heart’s health and rhythm. .

Chest X-Ray

Your chest x-ray reveals information about the lungs and the heart’s size and shape. The amount of radiation from a chest x-ray is extremely small. It will not cause any long-term side effects. However, it should not be performed on pregnant women, especially during the first trimester (three months) of pregnancy.


An echocardiograph is a cardiac ultrasound. It is a test that uses high-frequency sound waves to create an image of your heart. A Doppler test uses sound waves to measure blood flow. By combining these studies, your doctor learns about the heart’s structure and blood flow.  After the examinations and tests, your cardiologist will explain your heart condition in detail. Recommendations as to your diet, exercise, work, and any changes in lifestyle will be discussed. Your doctor will also tell you about any possible surgery and medical treatment.

Are there any other special tests?

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Sometimes the initial tests will not provide enough information for a diagnosis. Then your cardiologist may suggest that you have additional special tests. These might include any of the following:

Holter monitor

This is a portable electrocardiograph machine. It is about the size of a small tape recorder. You wear the machine continuously for approximately 24 hours while it records your heart beat. Your cardiologist can then learn about irregularities in your heart rhythm occurring during that time.

Heart Catheterization

If your heart condition is very complex, your doctor may recommend cardiac catheterization (heart cath). This procedure is often used in the treatment of coronary artery disease. Those who were diagnosed early in life may have had this test during infancy or in childhood. Today’s technology has greatly improved the comfort and effectiveness of heart ‘cathing’. It is used only to gather important information that would otherwise not be available.

Your cardiologist, or a doctor specially trained in heart catheterization, inserts a catheter (a small, flexible, plastic tube) into a vein or artery. This blood vessel is usually in the groin area, but sometimes a different site is used. A special x-ray technique allows the doctor to view the procedure. While your doctor watches the monitor, the catheter is slowly moved through the blood vessel until it reaches the heart. Your cardiologist can learn about the defect by taking blood samples and measuring blood pressures through the catheter.

During the heart cath a special fluid (a dye or contrast material) that can be seen by x-ray is injected through the catheter. An x-ray motion picture is recorded that helps to define the heart defect. This procedure is called angiography. Sometimes a heart defect can be treated during a heart cath. These treatments are different for each patient and will be discussed with you beforehand by your cardiologist.

An angiogram is the picture produced by heart catheterization. The shape of the chambers and blood vessels is shown when dye is injected through the catheter.

Magnetic Resonance Imaging (MRI)

Magnetic resonance imaging (MRI) is a way of taking highly detailed pictures of the soft tissues in your body. The MRI machine uses magnetism, not radiation, to obtain images. The test usually takes about 60 to 90 minutes to complete. During this time you will lie inside an open-ended chamber while the pictures are taken. The technician may give you an injection. This contains a contrast dye that allows some tissues to stand out better in the pictures.

There is no evidence that an MRI is harmful. However, you should not have an MRI if you have a heart pacemaker, an aneurysm clip in your head, shrapnel or bullets in your body, an ear implant (cochlear), or if you have metal in your eye.

An MRI gives a highly detailed picture of the heart. In this picture you can see how the major blood vessel, the aorta, is ‘pinched’. This is called coarctation of the aorta.

Nuclear Scans

Nuclear scans provide your doctor with very specialized information. A tiny amount of radioactive material is injected into the bloodstream. A special camera is able to ‘see’ where the material is distributed. The pictures that it takes are processed by a computer. There are different types of nuclear scans.

You may be scheduled fora MUGA (MultiGated Acquisition) scan. It is used to determine how well the ventricles of the heart are working. The picture that it takes is a ventriculogram. If you are scheduled for a perfusion scan, your doctor will be studying the flow of blood to your heart muscle. In this test the cells of the heart muscle absorb the radioactive material. This procedure is often called a thallium test because radioactive thallium is the material used.

How often will I need to see my cardiologist?

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Follow-up heart checkups are usually necessary to ensure that your heart maintains its maximum health. These are scheduled more often (that is, days, weeks, months) just after the diagnosis or surgery and less often later. Tests that regularly monitor your progress may be needed, depending upon your problem. Be prepared for

  1. Blood tests
  2. Electrocardiogram
  3. Holter monitor (24-hour ambulatory electrocardiogram)
  4. Chest x-ray
  5. Doppler/echocardiogram or exercise testing.
  6. On some occasions you may need follow-up cardiac catheterization.

Is surgery the only treatment for a congenital heart defect?

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Having a heart defect does not automatically mean you need an operation. Many heart defects do not need surgery, and some do not require treatment of any kind. It is possible for your cardiologist to find that drug therapy (medical treatment) is effective for you. For example, the drug digoxin can be used to regulate the force of the heart as it beats.

What do I need to know about surgery?

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Adults who had operations as children sometimes need new repairs. The wear-and-tear of time, aging, and growth can reduce the effectiveness of their first surgery. Whether your cardiologist finds that you need surgery or re-surgery, you will want to understand your defect, the recommended operation, and the expected results.

The goal of surgery is to repair your defect as completely as possible and to make your circulation as normal as it can be. Sometimes there are several ways to repair the malformed part of your heart or blood vessels. Your surgeon will discuss your options, and the benefits and risks of the operation with you. You may already have had more than one operation if you have a complex heart abnormality. A complicated heart defect may need to be fixed in several stages. Sometimes a complete repair of the heart is not possible. Surgery, however, may still be the best choice for gaining the best outcome possible for you. 

A surgical procedure is always a serious undertaking. Surgery on your heart may be especially frightening. Make sure that you are well prepared for it by talking with both your cardiologist and heart surgeon. Let them know your concerns. Remember that a heart surgery team is a well-trained group of dedicated professionals whose main concern is you.

What does having a problem with ‘heart rhythm’ mean?

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Your heart normally beats regularly at 50-150 beats per minute. This rate will vary depending on your age, sex, and degree of fitness. The medical term for an abnormality of heart rhythm is arrhythmia or dysrhythmia.

One type of abnormal rhythm is a very fast heart rate (tachycardia). It reduces the heart’s ability to pump. A very fast heart rate is sometimes related to a congenital heart defect, but it occurs in normal, healthy hearts too. If necessary, medication can be used to slow the heart rate to normal.

A very slow heart rate (bradycardia) can reduce the heart’s pumping ability. Some forms of this condition arise as a result of congenital heart defects. It can also occur after surgery. If your heart rhythm remains abnormally slow, you may need an artificial pacemaker.

There are many other types of arrhythmias. Most are temporary and have little effect on the health of your heart. Examples of these are irregular heart beats and skipped or missed beats. Sometimes an arrhythmia occurs after surgery. If the condition continues or if it affects the function of the heart in a serious way, your doctor may wish to regulate it with medical treatment.

What is congestive heart failure?

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During congestive heart failure the heart cannot pump out all the blood that returns to it. As a result, the heart cannot work well enough for the body to get the nourishment it needs for normal work and activity. Congestive heart failure does not mean that the heart stops working. However, fluid can build up in the lungs and make breathing difficult. Fluid may build up in the rest of the body and cause swelling. The signs of congestive heart failure include: fatigue upon exertion, rapid or laboured breathing, swelling, or several of these symptoms. Diuretics are a medication used to help get rid of this extra fluid. You may need to follow a low-salt diet. Other medical treatment may include digoxin or other drugs that can cause the heart to contract with more force.

What should I know about pregnancy and birth control?

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Young women with congenital heart defects often have special concerns when they think about having a baby. ‘Is my heart strong enough for a pregnancy’ and ‘Will my baby have a heart problem?’ are two of the most commonly asked questions.  Most women who have had successful heart surgery can have a normal pregnancy and delivery. If you are a woman with a very severe heart problem, pregnancy may be dangerous to both you and your child. It is very important that you consult with your cardiologist before attempting to become pregnant.

It is also important for women and couples to consider carefully what they choose to use for birth control. Some women should avoid the ‘pill’ and use other forms of birth control instead. Your cardiologist can give you advice about selecting the correct contraceptive method.

What is bacterial endocarditis?

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Bacterial endocarditis (BE) is an infection caused by bacteria that enter the bloodstream and settle in the heart lining (endocardium), a heart valve, or a blood vessel. It is a serious illness needing prompt medical attention.   Although endocarditis is uncommon, people with a heart defect have a greater risk of developing it than those with normal hearts. Thus, prevention (prophylaxis) is important. You must use antibiotics as a safeguard before having certain types of surgery or having any dental work. These procedures can allow germs to enter the bloodstream. 

Nearly everyone who has an unoperated heart defect needs to take antibiotics to prevent bacterial endocarditis. If you have had heart surgery, you may need this antibiotic protection too. You should be given antibiotics an hour or so before the surgery or dental procedure. Another dose should be given four to six hours later. Use antibiotics before having:

certain surgeries of the gastrointestinal, genital or urinary tracts,

dental procedures that may cause the gums or mouth to bleed, and

the removal of tonsils and adenoids.

Ask your cardiologist about how you can help prevent bacterial endocarditis. Be sure to carry the wallet card made available for you at your clinic. By showing this card to your dentist, family doctor or other physician, you are helping to ensure that you receive the safest and most complete care.

Types of defects

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There are over 35 types of congenital heart defects that exist, and often, more than one defect appears to create more complex cases.

The word “congenital” means existing at birth. The terms “congenital heart defect” and “congenital heart disease” are often used to mean the same thing, but “defect” is more accurate.

The heart ailment is a defect or abnormality, not a disease. A defect results when the heart or blood vessels near the heart don’t develop normally before birth. Working with your healthcare team, learn about the different types of congenital heart defects, treatments and tests

Obstructive Defects

These defects are those that cause blood flow to be decreased or blocked. They can affect arteries, veins or valves. They are:

  • Pulmonary Stenosis – narrowing of the pulmonary valve, which causes reduced blood flow to the lungs.
  • Aortic Stenosis – narrowing of the aortic valve, which causes reduced blood flow to the aorta, the artery that supplies the entire body with oxygenated blood.
  • Coarctation of the Aorta – the aorta itself is narrowed, and depending where the constriction occurs, it can cause decreased blood flow to the lower part of the body, or the entire body. The pressure above the constricted area is higher as a result.

Septal Defects

These defects are what are more commonly known as “holes in the heart”. They occur in the walls (septum) which separate the heart into four chambers. They can be small as a pin hole, and cause little to no problems, or as large as the entire wall being absent. These holes allow blood with oxygen and blood without oxygen to mix, and therefore, the blood going out to the body is not completely oxygenated. Three types of septal defects are:

  • Atrial Septal Defects (ASD) – a hole in the wall between the left and right atrium (top two chambers).
  • Ventricular Septal Defects (VSD) – a hole in the wall between the left and right ventricles (bottom two chambers).
  • Patent Ductus Arteriosus (PDA) – the ductus arteriosus is a blood passageway that exists in babies before they are born, which causes the blood to bypass the lungs of the fetus. Normally, this hole closes within a couple of hours of birth. When it doesn’t close normally, it is then referred to as a PDA.

Cyanotic Defects

These defects cause what is known as cyanosis, which results in a blue colouring of the lips and nail beds, commonly called “blue baby syndrome”. Many defects can cause cyanosis, such as septal defects, and the more complex heart defects. The cyanosis is due to the mixing of the oxygenated blood and the deoxygenated blood in the body. Most patients will have surgery to correct their defect which in turn will correct their cyanosis.  Cyanotic defects are:

  • Tetralogy of Fallot (TOF) – causes low oxygen levels in the blood. This leads to cyanosis (a bluish-purple color to the skin). Tetralogy of Fallot is rare, but it is the most common form of cyanotic congenital heart disease. Patients with tetralogy of Fallot are more likely to also have other congenital defects. The classic form includes four defects of the heart and its major blood vessels:
    • Ventricular septal defect (hole between the right and left ventricles)
    • Narrowing of the pulmonary outflow tract (the valve and artery that connect the heart with the lungs)
    • Overriding aorta (the artery that carries oxygen-rich blood to the body) that is shifted over the right ventricle and ventricular septal defect, instead of coming out only from the left ventricle
    • Thickened wall of the right ventricle (right ventricular hypertrophy)
    • Transposition of the Great Arteries (TGA) – the pulmonary artery and the aorta are switched in location, and therefore, the blood that should be going to the lungs to gain oxygen actually goes out into the aorta, and back through the body and the blood that should go to the lungs to get oxygen actually goes back to the lungs.
    • Ebstein’s Anomaly – the tricuspid valve that controls blood flow between the right atrium and the right ventricle is located lower than it should be, causing the right atrium to be larger, and the right ventricle to be much too small.

Defects Causing Obstruction in the Heart or Blood Vessels

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An abnormal narrowing in the heart’s valves or its blood vessels may partly block the movement of blood. Any one of the heart’s four valves can be affected. The blockage may occur in vessels that return blood to the heart or that carry it away. This narrowing is called stenosis. A stenosis may cause the heart to overwork because it must pump harder than normal to get blood past the narrowing.

The most common forms of obstruction to blood flow are pulmonary stenosis, aortic stenosis, and coarctation of the aorta. Pulmonary stenosis affects the flow of blood to the lungs. Aortic stenosis affects the aortic valve and the aorta, the major vessel leading to the body’s circulation. In coarctation of the aorta a specific section of the aorta is affected.

Those born with a heart defect today have a better-than-ever chance that the problem can be treated and that a normal life will follow. Recent progress in diagnosis and surgery makes it possible to fix most defects, even those once thought to be beyond repair. Both experience and research are building the foundation for improved and effective care. It is possible to believe that even the most complex of congenital heart problems can be managed, and that the quality of life of all those affected will be enhanced.

Links to Other Organizations and Resources

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Medical Resources

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Organ Donation Information

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