Atrial septal defect (ASD) occurs when there is a hole in the wall (septum) that divides the upper chambers (atria) of the heart.

As a baby’s heart develops during pregnancy, there are normally several openings in the wall dividing the upper chambers of the heart (atria). These usually close during pregnancy or shortly after birth.

In some children, the hole (ASD) may close on its own without treatment.

The hole increases the amount of blood that flows through the lungs. Over time, it may cause damage to the blood vessels in the lungs.

Damage to the blood vessels in the lungs may cause problems in adulthood, such as high blood pressure in the lungs and heart failure. Other problems may include abnormal heartbeat, and increased risk of stroke.

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Atrio-ventricular septal defect (AVSD) is a defect in which there are holes between the chambers of the right and left sides of the heart, and the valves that control the flow of blood between these chambers may not be formed correctly.

In AVSD, blood flows where it normally should not go. The blood may also have a lower than normal amount of oxygen, and extra blood can flow to the lungs.

This extra blood being pumped into the lungs forces the heart and lungs to work hard and may lead to congestive heart failure.

Early surgical repair is needed in most cases (in the first 4 - 6 months).

This video explains AVSD:

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Coarctation of the aorta is also called aortic narrowing. If your aorta is narrow, it means your heart must pump harder to force blood through the narrow part.

Although this condition can affect any part of the aorta, the defect is most often located near a blood vessel called the ductus arteriosus. Symptoms can range from mild to severe.

Treatment is usually successful, but this condition still requires careful lifelong follow-up.

This video explains Coarctation of the Aorta:

Coarctation of the aorta often occurs along with other heart defects.

Symptoms

Coarctation of the aorta commonly presents at birth. Sometimes it might not be detected until adulthood, depending on how much the aorta is narrowed.

Babies with severe coarctation of the aorta may begin having symptoms shortly after birth. The signs include pale skin, irritability, heavy sweating, difficulty breathing and feeding.

Adults with coarctation of the aorta may also have signs or symptoms of other heart defects, which often occur with the condition. Signs or symptoms of coarctation of the aorta after infancy commonly include high blood pressure, headaches, muscle weakness, leg cramps or cold feet, nosebleeds, and chest pain.

Learn more about Coarctation Of The Aorta.

Cyanotic congenital heart disease (CCHD) refers to a group of many different heart defects that result in a low blood oxygen level.

Cyanosis refers to a bluish colour of the skin and mucous membranes. This often occurs in the lips, toes or fingers.

Symptoms

• Blue lips, toes, or fingertips and palms.

Additionally, some children experience spells during which their oxygen levels are very low. As a result, they get anxious, which results in blue skin, and they may hyperventilate.

Causes

In many cases, genetics will play a role in a CCHD diagnosis.

• Family history: An infant is more at risk for CCHD when there’s a family history of congenital heart diseases.
• Genetic syndromes: Certain syndromes, such as down syndrome, can be accompanied by defects that cause CCHD.

In some instances, external factors can cause CCHD.

• Toxic chemicals or drugs during pregnancy: If a pregnant woman is exposed to toxic chemicals or certain drugs, it can negatively affect her infant's heart development.
• Infections during pregnancy: This can play a role in an infant developing CCHD.
• Gestational diabetes: Poorly controlled gestational diabetes can lead to a higher risk of an infant developing CCHD.

Hypoplastic left heart syndrome (HLHS) is a severe congenital heart defect in which the left side of the heart is underdeveloped or too small.

When this condition occurs, the left side of the heart cannot pump oxygen-rich blood to the body properly.

HLHS is amongst the most severe forms of heart defect. Most babies are very ill in the early days of life and need urgent surgery to survive.

This video explains HLHS:

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Hypoplastic right heart syndrome (HRHS) is a range of congenital defects in which the right-sided structures of the heart are underdeveloped or not formed.

When these structures (triscupid valve, right ventricle and/or pulmonary valve) are too small or do not function properly, the right side of the heart cannot send enough blood to the lungs.

Untreated HRHS causes a baby to have abnormally low oxygen levels.

Mitral valve disease occurs when the mitral valve doesn’t work properly, allowing blood to flow backward into the left atrium.

As a result, your heart does not pump enough blood out of the left ventricular chamber.

Mitral valve disease has many causes. Some forms of mitral valve disease can be present at birth (congenital).

Mitral valve regurgitation can be caused by problems with the mitral valve, also called primary mitral valve regurgitation. Mitral valve regurgitation is often caused by mitral valve prolapse, in which the mitral valve flaps (leaflets) bulge back into the left atrium. Diseases of the left ventricle can lead to secondary mitral valve regurgitation.

Mitral valve stenosis is often caused by rheumatic fever, which is a complication of a strep infection that can affect the heart.

Persistent ductus arteriosus (PDA) is the name of the tube that carries blood between the aorta and the pulmonary artery in the foetus.

This tube normally closes at or shortly after birth. Sometimes, however, the mechanism of closure does not work.

When the connection remains open, it causes blood to enter your lungs. This means your heart and lungs have to work harder.

If the PDA is small, it doesn't have to be closed because it doesn't make the heart and lungs work harder.

Aortic valve disease may be a heart defect condition present at birth (congenital).

Learn more about Persistent Ductus Arteriosus (PDA)

Pulmonary atresia is a defect of the pulmonary valve.

Your pulmonary valve usually controls the blood flow from the lower right chamber of the heart to the main pulmonary artery (the blood vessel that carries blood from the heart to the lungs).

Pulmonary atresia is when this valve doesn’t form, and no blood can go from the right ventricle of the heart out to the lungs.

Most babies with pulmonary atresia will need medication to keep the ductus arteriosus open after birth.

Keeping this blood vessel open will help with blood flow to the lungs until the pulmonary valve can be repaired.

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Pulmonary stenosis (also called pulmonic stenosis) is when the pulmonary valve (the valve between the right ventricle and the pulmonary artery) is too small, narrow, or stiff.

Symptoms of pulmonary stenosis depend on how small the narrowing of the pulmonary valve is.

If symptoms are mild, pulmonary stenosis may never need any treatment.

More severe pulmonary stenosis will need a procedure to fix the pulmonary valve so blood can flow properly through the body.

Causes

In children, pulmonary stenosis happens when a baby's heart doesn't develop the way it should during pregnancy.

Doctors don't know why this happens. It isn't caused by anything a mother did or didn't do during her pregnancy, so could not have been prevented.

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Pulmonary valve disease is a condition in which the pulmonary valve doesn't work properly. This condition can interrupt blood flow from the heart to your lungs.

The pulmonary valve is located between the heart's lower right heart chamber (right ventricle) and the artery that delivers blood to the lungs (pulmonary artery).

Treatment depends on the type and severity of the condition.

Single ventricle pathology occurs when one lower chamber (ventricle) does not develop.

This results in the heart having only one pumping chamber. The result is that the amount of oxygen-rich blood getting to the body is decreased.

In most children, the cause isn't known. Some children can have other heart defects at the same time too.

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Tetralogy of Fallot (ToF) is made up of a combination of four defects that commonly occur together.

ToF is made up of the following four defects of the heart and its blood vessels:

• Ventricular septal defect: A hole in the wall between the two lower chambers (ventricles) of the heart.
• Pulmonary stenosis: A narrowing of the pulmonary valve and main pulmonary artery.
• Ventricular hypertrophy: The muscular wall of the lower right chamber of the heart (right ventricle) is thicker than normal.
• Overriding aorta: Occurs when the aortic valve, which opens to the aorta, is enlarged and seems to open from both ventricles, rather than from the left ventricle only, as in a normal heart. In this defect, the aortic valve sits directly on top of the ventricular septal defect.

This video explains Tetralogy of Fallot:

What happens?

The abnormal flow of blood from the heart into the lungs leads to blood being diverted through the ventricular septal defect (VSD) to the aorta. Blood flow and lung circulation is reduced causing the child to appear blue.

Because a baby with ToF may need surgery or other procedures soon after birth, this birth defect is considered a critical congenital heart defect.

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Transposition of the great arteries (TGA) is a birth defect in which the two main arteries carrying blood out of the heart (the main pulmonary artery and the aorta) are switched in position, or 'transposed.'

In babies with TGA, oxygen-poor blood from the body enters the right side of the heart. But, instead of going to the lungs, the blood is pumped directly back out to the rest of the body through the aorta.

Oxygen-rich blood from the lungs entering the heart is pumped straight back to the lungs through the main pulmonary artery.

This video explains TGA:

TGA is considered a critical congenital heart defect.

This is because a baby with this defect may need surgery or other procedures soon after birth.

Other defects

Often, babies with TGA have other heart defects.

This can include a hole between the lower chambers of the heart (a ventricular septal defect) or the upper chambers of the heart (an atrial septal defect) that allow blood to mix so that some oxygen-rich blood can be pumped to the rest of the body.

The patent ductus arteriosus also allows some oxygen-rich blood to be pumped to the rest of the body.

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Ventricular septal defect (VSD) means there is a hole in the heart.

The hole occurs in the wall (septum) that separates the heart's lower chambers (ventricles) and allows blood to pass from the left to the right side of the heart. The oxygen-rich blood then gets pumped back to the lungs instead of out to the body.

A VSD happens during pregnancy if the wall that forms between the two ventricles does not fully develop, leaving a hole.

In a baby with a VSD, blood often flows from the left ventricle through the VSD to the right ventricle and into the lungs. This extra blood being pumped into the lungs forces the heart and lungs to work harder.

VSD is the most common type of congenital heart defect.

Over time, if not repaired, this defect can increase the risk for other complications, including heart failure, high blood pressure in the lungs (called pulmonary hypertension), irregular heart rhythms (called arrhythmia), or stroke.

Learn more about Ventricular Septal Defects.