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Tetralogy of Fallot is a rare condition resulting from a combination of four congenital heart defects that lead to the flow out of oxygen–poor blood from the heart to the rest of the body. This causes infants and children with the condition to have a bluish tinge to their skin due to insufficient oxygen levels in their blood.
The condition is typically diagnosed shortly after birth or in early childhood, although in some cases it may not be detected until adulthood depending on the severity of symptoms.
Surgery is necessary for all babies with tetralogy of Fallot, and patients may face activity restrictions and require ongoing medical care throughout their lives.
Symptoms
The degree of blood flow obstruction determines the specific symptoms of tetralogy of Fallot. Some warning signs and symptoms include:
- Cyanosis, a bluish discoloration of the skin brought on by insufficient blood oxygen levels
- Rapid breathing and shortness of breath, especially when eating or exercising
- Clubbing, an abnormally rounded nail bed in the fingers and toes
- Slow weight gain
- Gets tired easily while playing or working out
- Irritability
- Crying for a long time
- Heart murmur
- Fainting
Tet spells
Tetralogy of Fallot kids can experience abrupt development of vivid blue skin, lips, and nails after crying, eating, or becoming disturbed.
Episodes of decreased blood oxygen levels in individuals with tetralogy of Fallot are commonly referred to as “Tet spells“. These episodes usually occur in infants between the ages of 2 and 4 months, and are characterized by a sudden drop in blood oxygen levels. Toddlers or older children may instinctively squat during a Tet spell, as this can increase blood flow to the lungs.
If your infant exhibits any of the following signs or symptoms, get medical attention right away:
- The skin has a blue color
- Breathing problem
- Weakness
- Being irritable
- Seizures
- Fainting
Place your infant on his or her side and draw the knees up to the chest if he or she becomes blue (cyanotic). The lungs receive more blood as a result of this. Dial your local emergency number right away.
Causes
During pregnancy, as the baby’s heart develops, tetralogy of Fallot occurs. The cause is frequently unknown.
There are four types of defects in Tetralogy of Fallot, such as:
- Pulmonary valve stenosis. Blood flow to the lungs is decreased when the valve separating the right ventricle, the lower right chamber of the heart, from the pulmonary artery, narrows. The muscle below the pulmonary valve may also be impacted by the constriction. Pulmonary atresia is a condition in which the pulmonary valve does not develop normally.
- Ventricular septal defect. A hole in the septum, which divides the left and right ventricles of the heart, is referred to as a ventricular septal defect. The hole causes the right ventricle’s oxygen–poor blood to mix with the left ventricle’s oxygen–rich blood. Due to this, the body receives less blood that is oxygen–rich and has an inefficient blood flow. Over time, the defect may cause the heart to weaken.
- Shifting of the aorta. In a normal heart, the aorta typically originates from the left ventricle. However, in the case of tetralogy of Fallot, there is a misplacement of the aorta. It becomes shifted towards the right side and positioned directly above the ventricular septal defect, which is a hole in the wall separating the ventricles. Consequently, the aorta receives a combination of oxygen–rich and oxygen–poor blood from both the right and left ventricles.
- Right ventricular hypertrophy. The right ventricle’s muscular wall thickens when the pumping motion of the heart is strained. This may eventually result in the heart stiffening, weakening, and failing.
In some cases, tetralogy of Fallot may occur alongside other heart conditions in both children and adults. These may include an atrial septal defect, a right aortic arch, or problems with the coronary arteries.
Risk factors
Eventhough the precise cause of tetralogy of Fallot is unknown, there are some factors that could raise the likelihood that a baby will be born with this condition. The following are risk factors for tetralogy of Fallot:
- A viral infection like rubella (German measles), which can occur during pregnancy
- Consuming alcohol while pregnant
- Insufficient nutrition when pregnant
- An elderly mother (over 40)
- A parent suffering from tetralogy of Fallot
- If the baby has DiGeorge syndrome or Down syndrome
Diagnosis
Tetralogy of Fallot is typically identified shortly after birth. The skin of your baby might seem bluish. When listening to the baby’s heart with a stethoscope, the doctor might hear an unusual whooshing sound (heart murmur).
Tetralogy of Fallot is diagnosed by the following tests:
- Pulse oximetry (oxygen level measurement). The amount of oxygen in the blood is measured using a tiny sensor that is attached to a finger or toe.
- Echocardiogram. Sound waves are used in an echocardiography to produce images of the beating heart. Structure, location, and function of the heart wall, heart chambers, aorta, heart and pulmonary valves can all be seen during an echocardiography.
- Electrocardiogram (ECG or EKG). When the heart beats, an electrocardiogram captures the electrical activity that occurs. On the chest, wrists, and ankles during this test, sticky patches containing wires (electrodes) are applied. The computer that the wires are connected to shows the heart’s rhythm. The presence of an irregular heartbeat (arrhythmia) and enlargement of the heart chambers can both be detected using an ECG.
- Chest X–ray. An X–ray of the chest can reveal the heart and lung architecture. A heart with a boot shape is a common X–ray finding of tetralogy of Fallot because the right ventricle is enlarged.
- Cardiac catheterization. This test may be used by medical professionals to assess the heart’s structure and devise surgical strategies. In this technique, a thin, flexible tube (catheter) is inserted into a blood vessel, typically in the groin, and is then guided to the heart.
To make the heart components easier to observe on X–rays, dye runs via the catheter. During the procedure, the doctor can check the blood arteries and chambers of the heart for pressure and oxygen levels.
Treatment
Corrective surgery by a cardiovascular surgeon is necessary for all babies diagnosed with tetralogy of Fallot. Without this treatment, the child may experience growth and developmental issues. The specific surgical procedure and timing will be determined by the child’s condition and health. Prior to surgery, certain children may require medication to sustain the flow of blood from the heart to the lungs. This medication helps in maintaining adequate blood circulation until the surgical intervention takes place.
Surgery or other procedures
Open heart surgery to repair the flaws (intracardiac repair) or a short–term therapy with a shunt are the two options for treating tetralogy of Fallot. The majority of infants and older kids get intracardiac repair.
Intracardiac repair
Multiple repairs are made during this open–heart procedure, which is typically performed within the first year of life. In adults with tetralogy of Fallot who did not receive surgical repair as children, this procedure is very uncommon.
A surgeon performing an intracardiac repair will:
- Close the opening between the ventricles with a patch to cover the ventricular septal defect.
- To improve blood flow to the lungs, repair or replace the narrowed pulmonary valve.
After this treatment, the right ventricle wall will return to its usual thickness since it won’t need to exert as much effort to pump blood. The blood’s oxygen content rises and symptoms subside after intracardiac repair.
Temporary shunt surgery
Sometimes babies need a brief (palliative) operation before an intracardiac repair to enhance blood flow to the lungs. If your child was born preterm or has hypoplastic (underdeveloped) pulmonary arteries, this operation may be performed.
A big artery that arises from the aorta and the pulmonary artery are connected by a bypass (shunt) created by the surgeon during this treatment.
The surgeon removes the shunt when your infant is prepared for intracardiac repair and performs the intracardiac repair operation.
Post surgery
People who have undergone tetralogy of Fallot surgery continue to have higher long–term survival rates.
After tetralogy of Fallot surgery, blood flow to the lungs might occasionally remain be reduced. Additional operations might be required. Adults who have had their tetralogy of Fallot fixed may later need to have their pulmonary valve replaced if they have a leaky pulmonary valve (pulmonary valve regurgitation).
Arrhythmias are a typical consequence of tetralogy of Fallot repair surgery. Your doctor may advise taking certain medications, having the ablation, or getting an implantable cardioverter–defibrillator, a unique pacemaker used to treat arrhythmias that are life–threatening.
Ongoing care
Patients with tetralogy of Fallot require ongoing care from a pediatric or adult cardiologist to monitor the effectiveness of their treatment and watch for any potential complications. As part of routine checkups, imaging exams are often performed to evaluate the patient’s progress and the overall success of their treatment.
