Definition

Congenital heart disease is an abnormality in the heart's structure present at birth. While there are various types, this article will discuss four specific congenital heart defects: ventricular septal defect, atrial septal defect, patent ductus arteriosus, and tetralogy of Fallot.

Causes

To understand congenital heart disease in children, it's essential to grasp the blood circulation mechanism within the heart. The heart forms in the womb when the fetus is six weeks old and begins to pump blood for the first time. During this critical period, several major blood vessels also form. Congenital heart disease typically arises during this stage.

Cardiac Circulation Mechanism

The heart is divided into four main chambers: two atria and two ventricles, each separated by a wall to prevent blood from mixing. The heart uses its left and right sides to pump blood throughout the body. Blood enters the right atrium via the vena cava and flows into the right ventricle. From the right ventricle, blood is pumped to the lungs through the pulmonary artery.

Oxygen and carbon dioxide are exchanged in the lungs. Oxygenated blood flows through the pulmonary veins into the left atrium and the left ventricle. The left ventricle pumps this oxygen-rich blood to the rest of the body through the aorta. Thus, the right side of the heart pumps blood to the lungs, while the left pumps blood to the entire body except the lungs.

Ventricular Septal Defect (VSD)

A ventricular septal defect is a condition with a hole in the wall between the heart's two ventricles. The pressure in the left ventricle is much higher than in the right ventricle, causing oxygen-rich blood to flow into the right ventricle, leading to increased blood flow and pressure in the lungs and an increased workload for the right ventricle and lungs. Over time, this can cause heart damage.

Atrial Septal Defect (ASD)

An atrial septal defect is a condition in which there is a hole in the wall between the heart's two atria. Although the pressure in the atria is not significantly different, the left atrium's pressure is slightly higher, causing oxygen-rich blood to flow into the right atrium, increasing blood flow to the lungs, and adding to the workload of the right heart and lungs. While small ASDs may not cause problems and can sometimes close on their own, larger defects can cause heart damage.

Patent Ductus Arteriosus (PDA)

Patent ductus arteriosus occurs when the ductus arteriosus, a blood vessel that connects the pulmonary artery and aorta in a fetus, remains open after birth. This vessel usually closes shortly after birth. If the opening is small, it may not cause issues, but a larger opening allows oxygen-rich and oxygen-poor blood to mix, potentially causing long-term heart muscle damage.

Tetralogy of Fallot

Tetralogy of Fallot is a combination of four congenital heart defects:

• Pulmonary Stenosis: Narrowing the pulmonary valve reduces blood flow to the lungs.
• Ventricular Septal Defect: A hole between the ventricles allows blood mixing.
• Overriding Aorta: The aorta is positioned over both ventricles, receiving blood from both, causing mixed oxygen-rich and oxygen-poor blood to circulate throughout the body.
• Right Ventricular Hypertrophy: The right ventricle works harder, causing the muscle to thicken abnormally, eventually impairing its function.

Risk factor

The exact cause of congenital heart disease is unknown, but environmental and genetic factors include:

• Rubella infection during pregnancy: Immunization and immune status checks can reduce risk.
• Pre-pregnancy diabetes: Controlling blood sugar levels before and during pregnancy can reduce risk. Gestational diabetes usually does not increase risk.
• Medications: Certain drugs, such as thalidomide, ACE inhibitors, statins, isotretinoin, some anticonvulsants, and some anti-anxiety medications, can increase risk.
• Alcohol and smoking during pregnancy
• Smoking
• Family history and genetics: Some congenital heart diseases are inherited, and genetic conditions like Down syndrome can increase risk.

Symptoms

Symptoms vary depending on the type of congenital heart disease and often appear in childhood, except for the Tetralogy of Fallot. Symptoms of VSD include:

• Poor appetite and growth
• Shortness of breath
• Fatigue

ASD symptoms can be absent or include:

• Shortness of breath, especially during exercise
• Fatigue
• Swelling in the legs or abdomen
• Irregular heartbeat
• Palpitations

PDA symptoms can be absent or include:

• Poor appetite and growth
• Excessive sweating during feeding or crying
• Shortness of breath or rapid breathing
• Fatigue
• Rapid heartbeat

Symptoms of Tetralogy of Fallot include:

• Bluish skin (cyanosis)
• Worsening shortness of breath during feeding or activity
• Poor growth
• Fatigue
• Fainting
• Tet spells (intensified cyanosis during crying, feeding, or agitation), especially noticeable on the nails and lips

Diagnosis

A pediatric specialist diagnoses congenital heart disease, although a general practitioner may detect a heart murmur using a stethoscope. Further tests include:

• Pulse Oximetry: Measures blood oxygen levels.
• Chest X-ray: Shows heart enlargement and lung fluid.
• Electrocardiography (EKG): Detects electrical activity and structural problems.
• Echocardiography: Uses sound waves to visualize blood flow and assess the severity of defects. It can also be performed on a fetus.
• Cardiac Catheterization: Involves inserting a small tube into a blood vessel to reach the heart and assess valve and chamber function.

Management

Treatment depends on age, type, severity of the disease, and available resources. Doctors may observe symptoms for a few months, as some ASDs, VSDs, and PDAs may close on their own. Surgery can close these defects to prevent complications or reduce disease severity. Infants with congenital heart disease often need extra nutrition due to growth difficulties. Medications may also be prescribed to reduce heart workload if surgery is not feasible.

Complications

Complications include:

• Heart failure due to excessive workload
• Eisenmenger syndrome: high pulmonary artery pressure causing blood to flow back to the left heart, affecting untreated VSD, ASD, and PDA patients
• Arrhythmias: heart rhythm disorders
• Endocarditis: heart wall infection
• Growth and developmental delays due to inadequate oxygen and nutrients
• Stroke from blood clots traveling to the brain
• Mental health issues due to growth, learning difficulties, and activity limitations

Prevention

Preventing congenital heart disease is challenging once pregnancy occurs. However, prospective mothers can:

• Regularly visit a doctor before and during pregnancy
• Take vitamins with folic acid
• Avoid alcohol and smoking
• Immunize against rubella
• Control blood sugar levels
• Manage chronic conditions
• Avoid harmful substances (e.g., paint, cleaning fluids)
• Consult a doctor before taking any medication

When to see a doctor?

If your child has growth difficulties, frequent lung infections, or bluish skin, consult a pediatrician. The doctor will conduct tests to diagnose the condition, and you can collaborate on treatment.

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