Congenital heart disease

Definition

Congenital heart disease or childhood heart disease (CHD) is a collective term for structural abnormalities of the heart, aorta, or other large blood vessels which are present at birth. Congenital heart defects change the normal flow of blood to the heart. CHD is the most common form of birth defect in Australia, affecting up to 1 in 100 live-born babies.

There are many types of childhood heart diseases and the severity varies in every baby. Some defects are simple and do not require treatment, while others are more complex or life-threatening, and may require multiple surgeries over many years.

Congenital heart disease is classified into the following major categories:

• Holes in the heart may form in the septum (wall that separates the heart chambers) or between the major blood vessels. A hole will allow oxygen-rich and oxygen-poor blood to mix. If a lot of blood is mixed due to large holes in the heart, the blood circulated around the child’s body will not carry enough oxygen. This is commonly referred to as blue baby syndrome.
• Obstructed blood flow occurs when blood vessels or heart valves are narrower than normal due to a heart defect. When this happens, the heart muscle needs to work harder in order to pump blood through the valves and around the body. This can eventually lead to thickening or enlarging of the heart.
• Abnormal blood vessels occur when the blood vessels going to and from the heart do not form properly or are not positioned correctly, leading to a variety of heart defects. This ultimately affects the flow of oxygen-rich blood from the heart to the rest of the body.
• Heart valve abnormalities occur when heart valves cannot open and close properly, and oxygen-rich blood cannot flow easily to the rest of the body.
• An underdeveloped heart can occur when a major portion of the heart does not develop properly in the womb. As a result, the heart will not be able to work properly.
• A combination of defects can occur when babies are born with more than one heart defect which may have grave consequences for the child.

Types of congenital heart disease include: 

• Aortic Stenosis (AS)
• Atrial Septal Defect (ASD)
• Coarctation of the Aorta (CoA)
• Transposition of the Great Arteries (TGA)
• Ebstein's Anomaly
• Patent Ductus Arteriosis (PDA)
• Pulmonary Stenosis
• Tetralogy of Fallot
• Total Anomalous Pulmonary Venous Return (TAPVR)
• Truncus Arteriosus (TA)
• Ventricular Septal Defect (VSD)
• Hypoplastic Left Heart Syndrome (HLHS) Double Outlet Right Ventricle (DORV)

Symptoms

Serious cases of CHD are usually evident immediately after birth or during the first few months of life. Symptoms may include:

• Cyanosis – pale grey or blue skin colour
• Quick breathing
• Swelling in the legs, ankles,hands,abdomen or around the eyes
• Shortness of breath during feeding which can lead to poor weight gain

Congenital heart defects that are less serious may not present until later in childhood. These symptoms can include:

• Shortness of breath during exercise or activity
• Tiring easily during exercise or activity
• Swelling in the hands, ankles, or feet

Causes

The heart is the first organ to form in the body and starts to develop when an embryo is the size of a sesame seed. Within the first six weeks of pregnancy, the heart begins to take shape and starts beating. During this time, the major blood vessels that run to and from the heart also begin to form. At this critical point in development, heart defects may occur.

80 per cent of CHD cases remain unsolved which means doctors have no idea what caused them. Some of the known causes include:

• Genetic mutations affecting single genes, multiple genes contained within copy number duplications or deletions, or chromosomal abnormalities with or without syndromic association
• Maternal illness during pregnancy
• Medication or drugs. Some over the counter, prescription or illicit drugs may increase the risk of CHD
• Alcohol consumption during pregnancy
• Parental health – factors such as unmanaged diabetes or poor nutrition may increase the risk
• Environmental factors such as smoking and hypoxia (O2 deficiency)
• Maternal age 

Diagnosis

Severe heart defects are usually diagnosed during pregnancy or shortly after birth. Minor defects often have no signs and children are generally diagnosed when they are older. In addition to a regular physical exam, tests to diagnose CHD may include:

• Foetal echocardiogram
• Echocardiogram
• Electrocardiogram
• Chest X-ray
• Pulse oximetry (test used to measure the oxygen level of the blood)
• Catheterization 

Treatment

Treatments for heart defects vary according to the type of CHD. Defects that are very minor may have no long-term effects and can safely go untreated. In some instances they may even correct themselves as the child ages.

However other defects are more life-threatening and require treatment as soon as diagnosed. Treatment for these defects may require one or more of the following:

• Procedures using catheterization
• Open-heart surgery
• Heart transplant
• Medications

Children who have serious and complex heart defects are likely to require lifelong monitoring and treatment. Many will also need multiple surgeries, exercise restrictions, and infection prevention such as antibiotics.    

Prevention

Because eight out of ten cases of CHD have unknown cause, it is often not possible to prevent these conditions. However, there are ways you can reduce your child’s risk of overall birth defects:

• Vaccinate against Rubella (German measles) as the infection, during pregnancy, may affect a baby’s heart development
• Manage chronic medical conditions like diabetes and high blood pressure
• If you require medication for existing conditions, consult your doctor
• Avoid harmful substances while pregnant such as strong cleaning products, smoking, or alcohol
• Take a multivitamin with folic acid and vitamin B3

Click here to read about our world first breakthrough in congenital heart disease.

Research in congenital heart disease