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Congenital heart disease

What is congenital heart disease?

Congenital heart disease is condition you are born with. The word congenital means “present at birth.”

A congenital heart defect happens when the heart or the blood vessels near the heart don't develop normally before birth.

Congenital heart defects are present in about 1% of live births. They are the most frequent congenital malformations in newborns.

Often, there’s no known cause. In other cases, it may be caused by:

  • Viral infections such as measles (rubella),
  • Certain inherited conditions
  • Down Syndrome
  • Drug or alcohol abuse during pregnancy.

Survival of children with congenital heart disease has greatly improved thanks to medical advances in Canada and around the world.

  • Sixty years ago, fewer than 20% of infants born with complex heart defects reached adulthood.
  • Today, more than 90% do, including those with complex congenital heart defects.

Better quality care as adults can also help avoid or manage complications and live life to its fullest.


There are many types of congenital heart defects. To help you understand more about them, you may need to refer to the anatomy of the heart.

Obstruction of blood flow (stenosis)
Stenosis is a narrowing or obstruction that partly or completely blocks the flow of blood. Obstructions can occur in heart valves, arteries or veins. The three most common forms are:

  • Pulmonary stenosis The pulmonary valve, which lets blood flow from the right ventricles (the lower chambers) of the heart to the lungs, becomes narrowed. As a result, the right ventricle must pump harder than normal to overcome the obstruction. This may cause stress on, and enlargement of, the right ventricle.
  • Pulmonary atresia In this heart condition, the pulmonary valve, which lets blood flow from the right ventricles (the lower chambers) of the heart to the lungs, does not form properly and the valve remains closed at birth. This results in blood not being able to properly flow from the right ventricle into the lungs, where it goes to get oxygenated. If left untreated, this condition is fatal. Visit SickKids to learn more.
  • Tricuspid atresia In this heart condition, the tricuspid valve, which controls blood flow between the right atrium and the right ventricle, does not properly form and there is no opening between these two chambers. This results in blood not being able to properly flow from the right atrium into the right ventricle then onto the lungs, where it goes to get oxygenated. If left untreated, this condition is fatal. Visit SickKids to learn more.
  • Aortic stenosis The aortic valve, which controls the flow of blood between the left ventricle (the main pumping chamber of the heart) and the aorta, the large artery that carries oxygen-rich blood from the heart to the rest of the body, becomes narrowed making it difficult for the heart to pump blood to the body.  
  • Coarctation of the aorta The aorta is pinched or constricted, which obstructs the flow of blood to the lower part of the body and increases blood pressure above the constriction.

Septal defects (holes in the heart)
When a baby is born with an opening in the wall (the septum) that separates the right and left sides of the heart, blood flows between the right and left chambers of the heart instead of flowing normally to the rest of the body. This may cause the heart to become enlarged. This defect is commonly referred to as a "hole in the heart." The two most common forms are:

  • Atrial septal defect An opening exists between the atria (the upper chambers) of the heart. This allows some blood from the left atrium (blood that's already been to the lungs) to return, via the hole, to the right atrium. Normally, the blood should flow from the left atrium to the left ventricle, and from there out the aorta and to the body. The severity of the problem depends on the size of the opening.
  • A type of atrial septal defect is Patent Foramen Ovale (PFO). PFO is a hole that remains between the left and right atria after birth. Normally, this opening closes within the first few years of life. If it doesn’t, it usually causes no complications unless there are other accompanying heart defects. Visit SickKids to learn more.
  • Ventricular septal defect An opening exists between the ventricles (the lower chambers). Some blood that has returned from the lungs and has been pumped into the left ventricle flows to the right ventricle through the hole, instead of being pumped into the aorta and out to the body. The severity of the problem depends on the size of the opening.

Patent ductus arteriosus
The ductus arteriosus, a blood passageway that normally closes after birth, fails to close properly, causing too much blood to flow to the lungs. The severity of the problem depends on how large the opening is and how premature the baby is. Medications now exist to either close (or keep open) the ductus arteriosus. If, however, these medications do not work, procedures or surgeries are required. The majority of cases of this condition can be closed using catheter-based techniques, which are non-surgical procedures.

Cyanotic defects
In these defects, blood pumped to the body contains less-than-normal amounts of oxygen, causing cyanosis, a blue discoloration of the skin. The term "blue babies" is often applied to infants with cyanosis.

Tetralogy of fallot
This condition involves four defects that make the level of oxygen in the blood too low:

  • A large hole in the wall between the two ventricles that allows oxygen-poor blood to mix with oxygen-rich blood (ventricular septal defect)
  • A narrowing at, or just beneath or above, the pulmonary valve, which can block the flow of blood from the right side of the heart to the lungs; this narrowing typically occurs across all three areas
  • A more muscular than normal right ventricle
  • An aorta that lies directly over the right ventricle, allowing oxygen-poor blood to flow into the aorta.

Transposition of the great arteries
The position of the pulmonary artery and the aorta are reversed. Some type of opening (such as an atrial septal defect or ventricular septal defect) also exists between the right and left sides of the heart. The aorta is connected to the right ventricle, so most of the blood returning to the heart from the body is pumped back out without first going to the lungs to refresh with oxygen. The pulmonary artery is connected to the left ventricle, so that most of the blood returning from the lungs goes back to the lungs again.

Ebstein's anomaly
In this rare condition, the tricuspid valve, which controls blood flow between the right atrium and the right ventricle, is located lower than normal, causing the ventricle to be too small, and the atrium to be too large.


The most common signs and symptoms of congenital heart defects are:

  • A heart murmur
  • A bluish tint to skin, lips, and fingernails ("blue baby")
  • Fast breathing
  • Shortness of breath
  • Poor feeding, especially in infants because they tire easily while nursing
  • Poor weight gain in infants
  • Fatigue during exercise or activity (in older children).

A heart defect may be discovered during pregnancy, after birth or in adulthood, when the body puts greater demands on the heart. If a heart defect is suspected, you will be referred to a cardiologist (and in the case of a child, a paediatric cardiologist) who will take a family and medical history, do a physical examination, and order tests, which may include:

Read more about Tests


Most congenital heart defects can be treated with medication, catheter-based intervention (a non-surgical procedure) or surgery.

Here are the kinds of medication that may be used to help treat heart defects.

Inotropes strengthen the heart's ability to pump.

Prostaglandin E1 is used to keep the ductus arteriosus open in children who have a defect called patent ductus arteriosus until corrective surgery can be performed. This improves blood flow and oxygen levels until the defect is corrected.

Medications are also often needed after surgery. They may include:

In the first six months after surgery, antibiotics may be recommended before dental work or other invasive procedures to prevent infection of the heart (endocarditis). Speak to your doctor or dentist about antibiotics before dental work.

Non-surgical procedures
In many cases, the strain to the heart requires procedures that either fix holes between the chambers, replace valves or repair or reconnect major blood vessels. These are some of the procedures used to repair and correct congenital heart defects.

  • Cardiac catheterization is often used to repair simple holes in the heart. A catheter (thin tube) is inserted into a blood vessel in the groin or arm and guided to the heart so that a surgeon can insert a plug inside the hole to repair it.
  • Percutaneous coronary intervention (PCI or angioplasty with stent) is used to repair defective cardiac valves that can be either too narrow or leaky. A tiny balloon is guided to the heart inside a catheter (a thin tube). When the balloon is inflated, it can stretch the opening of a narrowed heart valve and restore normal blood flow. It is removed once blood flow returns. A stent is sometimes implanted to stabilize the dilated segment.  
  • Percutaneous valve implantation can also be used to place a bioprosthetic (artificial) valve in some patients.

Heart transplant is a surgery in which the defective heart is replaced by a healthy donor heart.

Living with congenital heart disease

Taking care of your children

SickKids has resources to help your kids understand heart disease with fun. Check out:

To learn more about congenital heart disease, visit SickKids on the following topics:

You can also visit The Canadian SADS Foundation to learn more about cardiac disorders that can cause sudden death in young people.

Living with congenital heart disease
Once teenagers with congenital heart disease have transitioned to adult care at age 18, they should be seen by a cardiologist specially trained in treating adults with congenital heart disease.

Visit the Canadian Congenital Heart Alliance (CCHA) to find an Adult Congenital Heart Disease Centre in Canada. You can help your child learn how to talk to doctors about their health conditions, and understand the importance of having health insurance and what medical care it covers.

People with congenital heart disease may be at risk of developing infective endocarditis (IE).

To reduce the risk of infection of the heart, talk to your doctor or dentist about the need for taking antibiotics before dental cleanings or surgery.

The Canadian Congenital Heart Alliance (CCHA) aims to improve the quality of life and health outcomes for individuals with congenital heart defects by raising awareness, providing peer support, mentoring and advancing research. Visit to learn more.


Related information

To find useful services to help you on your journey with heart disease, see our services and resources listing.


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