What is Tetralogy of Fallot?

Symptoms

The symptoms of Tetralogy of Fallot vary based on the amount of blood flow blocked. Here are the signs and symptoms of Tetralogy of Fallot:

• A bluish skin color produced by insufficient blood oxygen levels (cyanosis)
• Prolonged crying
• Fainting
• Tiring quickly during play or exercise
• Rapid breathing and shortness of breath, especially while feeding
• Irritability
• Heart murmur
• Poor weight gain
• The nail bed of the fingers and toes has an irregular, rounded shape (clubbing)

Tet spells

Babies with tetralogy of Fallot may have deep blue skin, lips, and nails, after crying or feeding, especially when agitated.

These are known as tet spells. A sudden reduction in blood oxygen levels causes tet spells. Tet spells are most common in infants aged 2 to 4 months. When toddlers or older children are out of breath, they may instinctively squat. Squatting enhances the flow of blood to the lungs.

Causes

Tetralogy of Fallot happens during pregnancy as the baby's heart is developing. In most cases, the cause is unknown. Four defects are found in the tetralogy of Fallot:

• Ventricular septal defect (a hole between the bottom heart chambers) A hole in the septum is known as a ventricular septal defect, which joins the two chambers of the heart (left and right ventricles). Due to the hole, oxygen-depleted blood in the right ventricle mixes with oxygen-rich blood in the left ventricle. This creates inefficient blood flow and lowers the body's supply of oxygen-rich blood. The defect can eventually weaken the heart.
• Aorta (shifting of the body's main artery) Normally, the aorta branches from the left ventricle. The aorta is in the incorrect position in the Fallot tetralogy. It's relocated to the right and is precisely above the hole in the heart wall. As a result, the aorta receives oxygen-rich and oxygen-depleted blood from both the right and left ventricles.
• Right ventricular hypertrophy (thickening of the right lower heart chamber) When the heart's pumping action is overworked, the right ventricle's muscular wall thickens. This may cause the heart to stiffen, weaken, and eventually fail over time.

Some children and adults with tetralogy of Fallot may also have other heart defects, like a hole between the heart chambers, a right aortic arch, or coronary artery issues.

Risk factors

While the precise cause of tetralogy of Fallot is unknown, many factors may rise the risk of a baby being born with this disorder. The following are risk factors for tetralogy of Fallot:

• A viral infection such as rubella during pregnancy (German measles)
• Pregnancy and alcohol consumption
• Pregnancy nutrition deficiency
• A mother over the age of 40
• A parent with Fallot tetralogy
• The baby's presence of Down syndrome or DiGeorge syndrome

Diagnosis

Tetralogy of Fallot is usually diagnosed shortly after birth. The skin of the baby may appear blue. When a doctor examines the baby's heart with a stethoscope, he or she may hear an abnormal whooshing sound (heart murmur). The following tests are used to diagnose tetralogy of Fallot:

• Pulse oximetry (Oxygen level measurement) Pulse oximetry (Oxygen level measurement): The amount of oxygen in the blood is measured using a small sensor inserted on a finger or toe.
• Echocardiogram Echocardiogram : An echocardiography creates images of the heart in motion using sound waves. The structure, functioning, and positioning of the heart chambers and heart wall, heart and pulmonary valves, and aorta can be revealed through echocardiography.
• Electrocardiogram Electrocardiogram (ECG or EKG): When the heart contracts, an electrocardiogram captures the electrical activity. During this procedure, electrodes are placed on the wrists, ankles, and chest. The wires are connected to a computer, which shows the heartbeat. An ECG can help establish if the heart chambers are enlarged and if the heartbeat is abnormal (arrhythmia).
• Chest X-ray Chest X-ray: The structure of the heart and lungs can be examined on a chest X-ray. Because the right ventricle is enlarged, tetralogy of Fallot users come on X-ray as a boot-shaped heart.
• Cardiac catheterization Cardiac catheterization: This test may be used by doctors to assess the anatomy of the heart and design a surgical plan. During this procedure, the surgeon places a thin, flexible tube (catheter) into a blood vessel, typically in the groin, and directs it to the heart.

Dye is injected through the catheter to make the cardiac structures visible on X-rays. The doctor can assess oxygen and pressure levels during the procedure.

Treatment

All newborns born with tetralogy of Fallot need corrective surgery by a heart (cardiovascular) surgeon. The infant may not grow and develop normally if you do not treat them. Based on you or your child's condition, the doctor will select the most appropriate procedure and schedule the surgery.

While waiting for surgery, some children may require medication to keep blood flowing from the heart to the lungs.

• Surgery or other procedure Tetralogy of Fallot surgery comprises either open-heart surgery to treat the abnormalities (intracardiac repair) or a temporary treatment that uses a shunt. The majority of infants and older children get an intracardiac repair.
• Intracardiac repair This open-heart surgery is usually performed within the first year of life and involves many repairs. Adults with tetralogy of Fallot who did not undergo surgical repair as children are unlikely to have this surgery. The surgeon will do the following during intracardiac repair:
  • Close the hole between the heart's lower chambers by patching over the ventricular septal defect (ventricles).
  • Repair or replace the constricted pulmonary valve to enhance blood flow to the lungs.
• Temporary shunt surgery Before intracardiac repair, newborns may need a temporary (palliative) operation to improve blood flow to the lungs. This treatment may be performed if the child was born prematurely. During this procedure, the surgeon builds a bypass (shunt) between a significant artery breaking out from the aorta and the pulmonary artery. When the infant is ready for intracardiac repair, the surgeon will remove the shunt during the procedure.