Tetralogy of Fallot- What is this heart defect ?

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Tetralogy of Fallot- What is this heart defect ?

Tetralogy of Fallot is a congenital heart defect that involves a combination of four heart abnormalities. It is named after the French physician Étienne-Louis Arthur Fallot, who first described the condition in 1888. The four components of Tetralogy of Fallot include:

• Ventricular Septal Defect (VSD): This is a hole in the wall (septum) that separates the two lower chambers (ventricles) of the heart. The hole allows oxygen-rich and oxygen-poor blood to mix.
• Pulmonary Stenosis: This is a narrowing or obstruction of the pulmonary valve or the pulmonary artery, which is the blood vessel that carries blood from the heart to the lungs.
• Overriding Aorta: In a normal heart, the aorta, the large blood vessel that carries oxygenated blood to the body, is connected to the left ventricle. In Tetralogy of Fallot, the aorta is positioned over the ventricular septal defect, allowing it to receive blood from both the right and left ventricles.
• Right Ventricular Hypertrophy: The right ventricle, which pumps blood to the lungs, becomes thicker and more muscular than normal because it has to work harder to overcome the obstruction of the pulmonary valve.

The combination of these four defects leads to mixing of oxygenated and deoxygenated blood, resulting in lower-than-normal levels of oxygen in the blood that is pumped to the body. Infants and children with Tetralogy of Fallot often have a bluish tint to their skin, lips, and nails, a condition known as cyanosis, due to the lack of oxygen. 

Surgical intervention is typically required to correct Tetralogy of Fallot. The timing of surgery may vary depending on the severity of the symptoms and the overall health of the child. Advances in medical care have allowed many individuals with Tetralogy of Fallot to lead relatively normal lives after corrective surgery. However, ongoing medical follow-up is usually necessary. ( Know more about- What are the septal defects of the heart ? )

What are symptoms and complications of this condition ?

Tetralogy of Fallot (TOF) can present with a range of symptoms and complications, and the severity can vary from person to person. The primary symptoms and potential complications include:

Symptoms:

• Cyanosis: The most characteristic symptom is cyanosis, which is a bluish tint to the skin, lips, and nails. This occurs because the blood pumped to the body has lower-than-normal levels of oxygen.
• Difficulty Breathing (Dyspnea): Individuals with Tetralogy of Fallot may experience difficulty breathing, especially during physical activity or feeding.
• Clubbing of Fingers and Toes: The chronic lack of oxygen in the blood can lead to clubbing, where the tips of the fingers and toes become rounded and enlarged.
• Poor Weight Gain and Growth: Infants with TOF may have difficulty feeding and may not gain weight as expected.
• Tet Spells (Tetralogy Spells): These are episodes of sudden, deep cyanosis and increased difficulty breathing. Tet spells can be triggered by various factors, such as crying or intense physical activity.

Complications:

• Arrhythmias: Irregular heart rhythms may develop, which can lead to palpitations or fainting.
• Infective Endocarditis: Individuals with congenital heart defects, including TOF, are at an increased risk of developing infective endocarditis, an infection of the heart lining or valves.
• Delayed Growth and Development: Chronic cyanosis and lower oxygen levels can affect the overall growth and development of a child.
• Pulmonary Regurgitation: Following surgical repair, there may be residual issues, such as leaking of the pulmonary valve, leading to blood flowing back into the right ventricle.
• Right Ventricular Dysfunction: Over time, the right ventricle may become weakened due to the increased workload, leading to heart failure.

Surgical Complications:

The primary treatment for Tetralogy of Fallot is surgical repair, usually done in infancy or early childhood. Complications related to surgery may include bleeding, infection, or issues with the repair that may require further intervention.  ( Know more about- What is Paediatric Cardiac Surgery? )

How common is this heart defect ?

Tetralogy of Fallot (TOF) is one of the more common congenital heart defects, accounting for a significant percentage of cases. The exact prevalence can vary by population and geographic region. It is estimated that Tetralogy of Fallot occurs in about 3 to 6 per 10,000 live births.

Congenital heart defects, including TOF, are structural abnormalities of the heart that are present at birth. The cause of these defects is often multifactorial, involving both genetic and environmental factors. While some cases of Tetralogy of Fallot may occur sporadically without a clear genetic cause, there is also a known association with certain genetic conditions and chromosomal abnormalities.

Advancements in medical and surgical interventions have significantly improved the outcomes for individuals with Tetralogy of Fallot. Many children with TOF can undergo successful surgical repair and lead relatively normal lives with appropriate medical care and follow-up. The prognosis depends on various factors, including the severity of the heart defects, the timing of surgical intervention, and the presence of any associated complications. ( Know more about- What is Pacemaker Surgery ? )

How can TOF be diagnosed ?

Tetralogy of Fallot (TOF) is often diagnosed during prenatal screening, at birth, or in infancy based on clinical signs and imaging studies. Here are some common diagnostic methods:

Prenatal Diagnosis:

• Fetal Echocardiography: This is an ultrasound examination of the developing fetus’s heart. It can reveal structural abnormalities, including Tetralogy of Fallot.

Postnatal Diagnosis:

• Clinical Examination: A newborn with Tetralogy of Fallot may exhibit cyanosis (bluish skin color), difficulty breathing, and other signs of congenital heart disease. A healthcare provider may suspect a heart defect based on these clinical findings.
• Pulse Oximetry: This non-invasive test measures the oxygen saturation in the blood. Low oxygen saturation can indicate a heart defect, including Tetralogy of Fallot.
• Chest X-ray: X-rays can show an enlarged heart and the characteristic “boot-shaped” appearance of the heart due to the enlarged right ventricle.
• Electrocardiogram (ECG or EKG): This test records the electrical activity of the heart and can help identify abnormal rhythms and signs of right ventricular hypertrophy.
• Echocardiogram: This is a key diagnostic tool for Tetralogy of Fallot. It uses sound waves to create detailed images of the heart’s structure and function, allowing healthcare providers to visualize the ventricular septal defect, pulmonary stenosis, overriding aorta, and right ventricular hypertrophy.

Additional Diagnostic Tests:

• Cardiac MRI (Magnetic Resonance Imaging): Provides detailed images of the heart’s structure and blood flow, helping to assess the severity of the defects.
• Cardiac Catheterization: In some cases, a catheter may be threaded through blood vessels to the heart to obtain more detailed information about the defects and pressure within the heart chambers.

Early diagnosis is crucial for timely intervention and management. If Tetralogy of Fallot is suspected, the child is usually referred to a pediatric cardiologist for further evaluation and confirmation of the diagnosis. Once diagnosed, a treatment plan, often involving surgical repair, will be developed to address the specific needs of the individual with Tetralogy of Fallot. Get early detection of heart defects and other diseases by getting health checkups. Get full body checkups at Manipal Hospital Old Airport Road Bangalore.