tetralogy of Fallot



OVERVIEW

Definition

Tetralogy of Fallot is a right-to-left shunting (also known as cyanosis) congenital heart disease consisting of 4 malformations characterized by right ventricular outflow tract obstruction, ventricular septal defect, aortic ride, and right ventricular hypertrophy, and is the most common right-to-left shunting congenital heart disease.

Incidence

There are 3-6 cases of tetralogy of Fallot per 10,000 deliveries, accounting for 5% to 7% of congenital heart disease.

Causes

Causes

The cause of the disease is unknown and may be related to genetic and maternal factors.

Genetic factors

Tetralogy of Fallot has a tendency to run in families and is associated with single gene defects and chromosomal aberrations.

Maternal factors

Viral infections: especially viral infections in early pregnancy, such as rubella, influenza, mumps, coxsackie virus infections, etc.

Drugs: including thalidomide, angiotensin-converting enzyme inhibitors, statins, isotretinoin, anti-epileptic drugs, etc.

Certain diseases: diabetes, hypercalcemia, phenylketonuria, systemic lupus erythematosus during pregnancy.

Exposure to radiation or certain chemicals during pregnancy.

Smoking or second-hand smoke, drinking alcohol during pregnancy.

Intrauterine oxygen deprivation of the fetus.

Folic acid deficiency during pregnancy.

Pathogenesis

Tetralogy of Fallot is a congenital disorder with an unknown pathogenesis, which may be due to some early embryonic cause of hypoplasia of the funnel or cone of the fetal heart.

Symptoms

Tetralogy of Fallot can usually present with abnormal symptoms in the first 3 to 6 months of life, but there are also cases in which symptoms appear immediately after birth.

Main symptoms

Cyanosis of the skin and mucous membranes

Also known as cyanosis and violet cyanosis, it is the first symptom to appear.

It is usually seen from 6 months to 1 year after birth, but can also appear soon after birth.

It is mainly manifested by the blue-purple color of finger and toe nails and lips.

Symptoms are more pronounced when you cry or become agitated.

The older the child, the more severe the symptoms.

Hypoxic seizures

Most often occur in infants and children under 2 years of age.

It often occurs just after waking up from a deep sleep, when drinking milk, crying, defecating, or exerting themselves during activities.

The main manifestations are sudden rapid breathing, increased bruising, confusion and convulsions (sudden jerking of the whole body) if the attack lasts for a long time.

Older children may have dizziness and headache.

Crouching Symptoms

Older children often squat suddenly while playing or walking to relieve discomfort caused by lack of oxygen.

Small infants who cannot walk often prefer to be picked up by an adult and prefer to bend both lower limbs.

Pestle-like fingers (toes)

Most commonly seen in infants and young children about 6 months after birth.

It is characterized by thick, drumstick-like ends of the fingers and toes.

Other symptoms

Growth retardation: lower height and weight than healthy children of the same age.

Shortness of breath: exacerbated by crying, breastfeeding and activity.

Easy fatigue.

Nosebleeds or hemoptysis.

Complications

Cerebral thrombosis: newborns and infants are asymptomatic and may present with twitching of the limbs.

Brain abscess: may present with high fever, apathy, lethargy, headache and vomiting.

Infective endocarditis: may present with fever, skin petechiae and other symptoms.

Heart failure: manifested by different degrees of dyspnea, shortness of breath, coughing, coughing up sputum, hemoptysis, loss of physical strength, etc. In severe cases, drowsiness and coma may occur.

Consultation

Department of Medicine

Pediatrics

It is recommended to consult a doctor if any of the following occurs

Lip and skin bruising after birth, aggravated by breastfeeding or crying.

Have symptoms such as difficulty in breathing and large finger (toe) tips.

Frequent and sudden squatting during activities or play.

Preparation for medical treatment

Consultation: Registration, Preparation of information, Frequently Asked Questions (FAQ)

Tips

Minimize the baby’s activities and focus on resting so as not to aggravate the symptoms of hypoxia.

Preparation List

Symptom list

Pay particular attention to the time of onset of symptoms, special manifestations, etc.

When did the symptoms of cyanosis, dyspnea and shortness of breath start?

Do the symptoms worsen with activity or crying?

Does the baby crouch for a few moments when moving or walking (crouching)?

Does the baby have a fever?

Medical History Checklist

Is there a family history of congenital heart disease?

Checklist

Test results for the past 6 months, which can be brought to the doctor’s office

Laboratory tests: blood test, C-reactive protein, blood gas analysis

Imaging tests: cardiac ultrasound

Medication List

Medication in the last 3 months, if available, bring along the box or package to the doctor.

Cardiotonic drugs: Deacetyl furfuryl glucoside

Diuretics: spironolactone, hydrochlorothiazide

Diagnosis

Diagnosis is based on

Initial diagnosis can be made on the basis of history and typical clinical manifestations. Confirmation of the diagnosis relies mainly on electrocardiography, chest X-ray and echocardiography.

Medical history

Family history of tetralogy of Fallot.

The mother has a history of drug use, exposure to harmful substances, and infections during pregnancy.

Clinical manifestations

Bruising of the skin and mucous membranes, fatigue, crouching, and hypoxic episodes may be present immediately or gradually after birth.

There may also be pestle-like fingers (toes), growth retardation, systolic murmur at the left edge of the sternum between the 2nd and 4th intercostal space with a weakened second heart sound.

Blood tests

These include routine blood tests, blood biochemical tests, and arterial blood gas analysis.

They are mainly used to determine the nutritional status and the presence of hypoxia, except for other diseases.

There may be obvious increase in peripheral blood red blood cell count and hemoglobin concentration, decrease in platelets, and obvious decrease in arterial oxygen saturation.

Electrocardiography

Electrocardiography can determine the presence of arrhythmia and cardiac enlargement.

There may be rightward deviation of the electrical axis, as well as right atrial hypertrophy, right ventricular hypertrophy, and incomplete right bundle branch block.

Imaging

Echocardiography

Echocardiography is the test of choice for the diagnosis of tetralogy of Fallot and is also valuable in the choice of surgical approach.

It can visualize the type and size of the heart defect from different angles, and can also understand the development of the pulmonary arteries and evaluate cardiac function.

The examination may reveal the presence of four simultaneous malformations of the heart: ventricular septal defect, aortic riding, right ventricular outflow tract obstruction, and right ventricular hypertrophy.

Chest X-ray

It is a routine examination.

The size of the heart and the distribution of blood to the lungs can be observed.

A clear “boot” shape of the heart can be detected during the examination.

Magnetic Resonance Imaging (MRI) of the Chest

This is an elective test.

It can accurately visualize the anatomy of the right ventricular outflow tract and pulmonary artery branches, evaluate ventricular function, and help assess surgical outcomes.

The disadvantage is that the examination takes a long time and requires a fixed position and breathing control, which is difficult for newborns and infants.

Multi-slice spiral CT angiography (CTA)

It has gradually replaced cardiac catheterization and cardiovascular angiography.

It can evaluate the development of peripheral pulmonary arteries and ventricles, the type of ventricular septal defects, coronary artery malformations, and intra-pulmonary collateral circulation vessels.

Cardiac catheterization and angiography

Once the “gold standard” of diagnosis, these tests are not recommended as routine.

They can clarify the type of ventricular septal defect, the development of pulmonary arteries, and the distribution of coronary arteries, and can also measure the pressure in each atrium and ventricle.

It can also measure the pressure of each atrium and ventricle. It is mainly used for those whose anatomy of pulmonary artery branches is not clear.

Differential diagnosis

Tetralogy of Fallot needs to be differentiated from other cardiovascular diseases with similar symptoms.

Tetralogy of Fallot

Similarities: All may present with cyanosis, squatting symptoms, shortness of breath, easy fatigue, etc. On auscultation, all may have a jet systolic murmur in the 2nd intercostal space at the left edge of the sternum.

Differences: Farrow’s syndrome presents with late cyanosis, and squatting is rare; chest X-ray shows enlargement of the right ventricle and right atrium, and prominent pulmonary artery segments; echocardiography reveals characteristic manifestations that can be clearly differentiated.

Eisenmenger syndrome

Similarities: both may present with cyanosis, pestle-like fingers (toes), shortness of breath, and easy fatigue.

Differences: Eisenmenger’s syndrome has a later and milder appearance of cyanosis, and X-ray examination shows that the arc of the pulmonary artery trunk is obviously protruding, the pulmonary portal blood vessel shadow is thick, and the peripheral blood vessel shadow of the lung field is thin, and the right heart catheterization and echocardiographic examination can show signs of obvious elevation of the pulmonary artery pressure.

Transposition of the great arteries

Similarities: Both may have skin and mucous membrane bruising, shortness of breath, pestle-like fingers (toes), and growth retardation that occurs immediately after birth.

Differences: Transposition of the great arteries is a congenital malformation with abnormal transposition of the aorta and pulmonary arteries. Echocardiography and selective right ventriculography can clearly identify the transposition of the aorta and pulmonary arteries.

Permanent arterial trunk

Similarities: Both can present with cyanosis and shortness of breath shortly after birth.

Difference: When the truncus arteriosus survives, there is only one set of semilunar valves spanning both ventricles, from which the pulmonary and cephaloarterial arteries emanate, and which can be differentiated by the presence of characteristic structures on echocardiography and selective right ventriculography.

Treatment

All patients diagnosed with tetralogy of Fallot should be treated surgically to correct the deformity, while medical treatment is mainly used to control the condition.

Medical treatment

General management

Rest: avoid exertion and physical activities.

Adjust diet: Drink plenty of water and give nutritious and easy-to-digest food.

Adjust the feeding method: feed babies and young children small amounts of milk several times.

Prevent infection: Keep warm and protect from cold, keep the room air well ventilated.

Treatment of hypoxic episodes

Change of body position: Keeping the knees close to the chest is suitable for those with mild symptoms.

Medication: Commonly used medications are propranolol and morphine for those with severe symptoms.

Oxygenation.

Rehydration: Correct acidosis.

Prevention of hypoxic attack

Normally, we should remove the triggers that can cause hypoxic attack, such as anemia, infection, crying and so on.

For those who have severe symptoms and frequent attacks during hypoxic episodes, medication should be applied to prevent them, and the commonly used medication is propranolol.

Surgical treatment

Palliative surgery

It is suitable for those with severe disease, poor general condition or other conditions that do not allow radical surgery.

Palliative surgery increases pulmonary blood flow, improves arterial oxygen saturation, promotes the development of the left ventricle and pulmonary vasculature, and helps the child to survive until radical surgery is indicated.

Commonly used palliative procedures include subclavian artery-pulmonary artery shunt and superior vena cava-right pulmonary artery anastomosis.

The need for radical surgery needs to be reassessed after 1 to 1 1/2 years postoperatively.

Radical surgery

Indications: normal left ventricular development and well-developed pulmonary artery.

Contraindications: Intractable heart failure, severe hepatic and renal impairment.

Age of surgery: There is no standardized criteria, and the decision needs to be made according to the severity of the disease. Most of the time, surgery is performed before the age of 2-3 years, and in severe cases, surgery can be performed in the first 3-6 months of life.

Prognosis

Cure

Tetralogy of Fallot cannot be cured by itself.

With prompt surgical treatment, most of them can be cured. In a small number of cases, pulmonary regurgitation, arrhythmias, residual outflow tract obstruction, tricuspid regurgitation, and residual shunt of ventricular septal defect will still be present after surgery.

Without surgical treatment, mortality increases progressively with age.

Hazards

Symptoms such as generalized bruising and shortness of breath can be seen after birth, which affects the normal growth and development of infants.

Affected children often need to crouch down to rest during activities and games, which interferes with normal activities.

Affected children cannot perform strenuous exercise when they grow up.

It can lead to complications such as cerebral thrombosis, brain abscess, infective endocarditis and heart failure, which can be life-threatening in severe cases.

Daily

Daily management

Reasonable feeding

Enhance nutrition, provide easy-to-digest, high protein, high calorie and high vitamin diet.

Feed small amount of food several times and avoid overfilling.

When feeding, use a dropper to reduce physical exertion of the child.

Avoid stimulation

Minimize activities and avoid strenuous and intense exercise.

Avoid factors that may cause the child to cry and become agitated.

Drink plenty of water to avoid constipation.

Avoid infection

Pay attention to environmental hygiene, ventilate the room frequently, and maintain appropriate temperature and humidity.

Pay attention to cold and warmth, avoid cold.

Pay attention to oral hygiene, brush teeth in the morning and evening.

Wash your hands frequently.

During the epidemic period of influenza and other infectious diseases, go to shopping malls and other densely populated places less often.

Keep the incision clean and dry after surgery to prevent wound infection.

Follow-up

Follow your doctor’s instructions for regular follow-ups. You need to go to the hospital for follow-ups 1 month, 3 months and 1 year after surgery.

If symptoms reappear after treatment, or if new symptoms appear, you should seek medical attention.

Prevention

There are no particularly effective preventive measures for Tetralogy of Fallot. Good health care before and during pregnancy may help in prevention.

Preconception care

Those who are already suffering from diabetes or taking special medication when preparing for pregnancy should consult their doctors on the precautions and treatments for preparing for pregnancy.

Those who are preparing for pregnancy should have regular medical checkups and take active treatment when they are sick.

Health care during pregnancy

Reduce and avoid viral infections during pregnancy and go to less crowded places.

Use drugs carefully during pregnancy, especially those that may cause fetal malformation.

Avoid exposure to radiation as much as possible during pregnancy, including examination, treatment and living in areas where there is much suspected radiation.

Actively perform relevant examinations during pregnancy for early detection of fetal congenital malformations.