Tetrada Fallot: symptoms, diagnosis, treatment

The tetralogy of Fallot consists of the following 4 congenital malformations: a large defect of the interventricular septum, an obstruction to the flow of blood at the exit from the right ventricle (stenosis of the pulmonary artery), right ventricular hypertrophy and "sitting aorta". Symptoms include cyanosis, dyspnea during feeding, impaired physical development, and hypoxemic seizures (sudden, potentially fatal episodes of severe cyanosis). Often a rough systolic murmur on the left side of the sternum in the II-III intercostal space with a single tone II is heard. Diagnosis is based on echocardiography or cardiac catheterization. Radical treatment is surgical correction. It is recommended to prevent endocarditis.

The tetralogy of Fallot is 7-10% of congenital heart defects. Often there are other defects, except for the four above; they include a right aortic arch (25%), anomalies of the coronary artery anatomy (5%), stenosis of the pulmonary artery branches, the presence of aortolateral collateral vessels, an open arterial duct, complete atrioventricular communication and regurgitation on the aortic valve

What is the tetralogy of Fallot?

The tetralogue of Fallot includes four components:

• a suportortal (high membranous) defect of the interventricular septum, which creates conditions for equalizing the pressure in both ventricles;
• obstruction of the exit from the right ventricle (stenosis of the pulmonary artery);
• hypertrophy of the myocardium of the right ventricle due to obstruction of its exit;
• dextrase of the aorta (the aorta is located directly above the defect of the interventricular septum).

The position of the aorta can vary to a large extent. The last two components practically do not affect the bleeding hemodynamics. Pulmonary artery stenosis in the tetralogy of Fallot is infowdibular (low, high and in the form of diffuse hypoplasia), it is often combined with the valve due to the bivalve structure of the valve. Children of the first months of life often, and with atrezion of the valves of the pulmonary artery (the so-called extreme form of the tetralogy of Fallot) - almost always function aorto-pulmonary collaterals (including the open arterial duct) ..

Defect of the interventricular septum (DMV) usually has large dimensions; so the systolic pressure in the right and left ventricles (and in the aorta) is the same. Pathophysiology depends on the degree of obstruction of the pulmonary artery. With a small obstruction to the blood flow, left-right blood discharge through the VSW can occur; with severe obstruction, a discharge of blood from the right to the left develops, which leads to a decrease in systemic saturation in the arterial blood (cyanosis) that does not respond to oxygen therapy.

Patients who have tetralogy of Fallot can suffer from sudden attacks of generalized cyanosis (hypoxemic seizures), which can lead to death. The attack can be provoked by any condition in which the oxygen saturation (for example, crying, defecation) decreases slightly or systemic vascular resistance suddenly decreases (for example, play, kicks on waking), or a sudden attack of tachycardia and hypovolemia. A vicious circle can develop: first, the decrease in PO2 of the arterial blood stimulates the respiratory center and causes hyperpnoea. Hyperpneumonia increases the systemic venous return to the right ventricle, making the suction effect of negative pressure in the thoracic cavity more pronounced. If there is persistent disturbance of the flow of blood from the right ventricle or reduced systemic vascular resistance, an increased venous return to the right ventricle is sent to the aorta, thus reducing the oxygen saturation and closing the vicious circle of the hypoxemia attack.

Symptoms of tetralogy of Fallot

In newborns with significant obstruction, the flow of blood from the right ventricle (or pulmonary atresia) shows marked cyanosis and shortness of breath when fed with low body weight gain. However, with minimal stenosis of the pulmonary artery, neonatal rest can not have cyanosis.

Hypoxemic seizures can be provoked by motor activity and characterized by paroxysms of hyperpnoea (frequent and deep breaths), anxiety and prolonged crying, increasing cyanosis and a decrease in the intensity of noise in the heart. Seizures most often develop in infants; peak occurrence is observed at the age of 2-4 months. Severe seizures can lead to lethargy, seizures and sometimes death. During the game, some children can squat, this position reduces systemic venous return, probably increases systemic vascular resistance and thus increases oxygen saturation in the arterial blood.

Leading symptoms of tetralogy of Fallot are dyspnea-cyanotic attacks up to loss of consciousness, developing as a result of a spasm of the already stenosed pulmonary artery. Hemodynamic changes: during systole blood from both ventricles enters the aorta, in a smaller amount (depending on the degree of stenosis) - in the pulmonary artery. Location of the aorta "on horseback" on the defect of the interventricular septum leads to unhindered ejection of blood from the right ventricle into it, so that the right ventricular failure does not develop. The degree of hypoxia and severity of patients' condition correlate with the severity of pulmonary artery stenosis.

In the physical examination, the heart region is not visually changed, systolic jitter is revealed parasternally, the boundaries of relative cardiac dullness are not expanded. Tones of satisfactory loudness, listen to a rough systolic noise along the left edge of the sternum due to the stenosis of the pulmonary artery and the discharge of blood through the defect. The second tone over the pulmonary artery is weakened. The liver and spleen are not enlarged, there are no swelling.

In the clinical picture, the Phallus tetrad is divided into several stages of relative well-being: from birth to 6 months, when the infant's motor activity is low, cyanosis is poor or moderate; the stage of blue attacks (6-24 months) is clinically the most difficult stage, so it proceeds against a background of relative anemia without a high level of hematocrit. The attack is read off suddenly, the child becomes restless, shortness of breath and cyanosis increase, noise intensity decreases, apnea, loss of consciousness (hypoxic coma), convulsions followed by hemiparesis. The occurrence of seizures is associated with a spasm of the excretory portion of the right ventricle, as a result of which all the venous blood is discharged into the aorta, enhancing the hypoxia of the central nervous system. The attack provokes physical or emotional stress. With a deterioration of well-being and an increase in hypoxia, children take a forced position on their haunches. In the subsequent develops a transitional stage of vice, when the clinical picture acquires features characteristic of older children. At this time, despite the increase in cyanosis, seizures disappear (or children prevent them by taking a squatting position), tachycardia and dyspnea decrease, polycythemia and polyglobulia develop, the lungs form collateral circulation.

Diagnosis of tetralogy of Fallot

The diagnosis of "tetralogy of Fallot" is based on anamnesis and clinical data, taking into account the chest radiograph and ECG, an accurate diagnosis is established based on two-dimensional echocardiography with color Dopplercardiography.

ECG helps to identify the deviation of the electrical axis of the heart to the right from +100 to + 180 °, signs of myocardial hypertrophy of the right ventricle. Often a complete or incomplete blockage of the right leg of the bundle is revealed.

Radiographically, a depletion of the pulmonary pattern is detected. The heart shape is usually typical - in the form of a "wooden shoe", due to the rounding and raised above the diaphragm of the apex and westing of the pulmonary artery. The shadow of the heart is small, the increase can be with pulmonary artery atresia.

Echocardiography allows most patients to diagnose with the completeness sufficient to determine the tactics of treatment. All the characteristic signs of a defect are revealed: pulmonary artery stenosis, a large defect of the interventricular septum, right ventricular hypertrophy and aortic dextrase. With the help of color dopplerography, a typical direction of the flow of blood from the right ventricle into the aorta can be recorded. In addition, hypoplasia of the ventral tract of the right ventricle, the trunk and branches of the pulmonary artery is revealed.

Cardiac catheterization and angiocardiography are performed with unsatisfactory echocardiographic visualization of the heart and vascular structures or in case of detection of any additional anomalies (atresia of the pulmonary artery, suspicion of peripheral stenoses, etc.).

Differential diagnosis of tetralogy of Fallot is carried out, first of all, with a complete transposition of the main vessels.

Differential diagnosis of tetralogy of Fallot and transposition of the main vessels

Clinical signs	Congenital heart defect
	Tetrad of Fallot	Transposition of the main arteries
Dates of diffuse cyanosis	From the end of the first to the beginning of the second half of life, a maximum of two years	Since birth
Congestive pneumonia in history	No	Frequent
Presence of a heart hump	No	There is
Expansion of the borders of the heart	Not typical	There is
Sound of 2nd tone in the second intercostal space on the left	Weakened	Strengthened
Noise	Systolic murmur along the left edge of the sternum	Corresponds to the location of companion communication
Signs of right ventricular failure	None	There is

[1], [2], [3], [4], [5], [6], [7]

Treatment of tetralogy of Fallot

Newborns in the presence of severe cyanosis due to the closure of the arterial duct are infused with prostaglandin E1 [0.05-0.10 μg / (kg x min) intravenously] in order to reopen the arterial duct.

In a hypoxemic attack, the child should be given a pose with knees pressed to the chest (older children squat and they do not develop an attack) and prescribe morphine 0.1-0.2 mg / kg intramuscularly. Intravenous fluids are used to increase the volume of circulating blood. If these measures do not stop the attack, systemic blood pressure can be increased by administering phenylephrine at 0.02 mg / kg intravenously or ketamine at 0.5-3 mg / kg intravenously or 2-3 mg / kg intramuscularly; Ketamine also has a sedative effect. Propranolol 0.25-1.0 mg / kg orally every 6 hours can prevent relapses. The effect of oxygen therapy is limited.

Tetrada Fallo is treated in two cases:

• treatment of dyspnea-cyanotic attack (urgent therapy);
• surgical treatment.

Operative treatment, depending on the anatomical structure of the defect, can be palliative (aorto-pulmonary anastomosis) or radical (elimination of stenosis and plastic of the interventricular septum).

The dyspnea-cyanotic attack is stopped with oxygen therapy. Intramuscular administration of trimeperidine (promedol) and niketamide (cordiamine), correction of acidosis and improvement of the microcirculatory bed by intravenous drip introduction of appropriate solutions (including a polarizing mixture). It is possible to use sedatives and vasodilators. To specific therapy carry beta-adrenoblockers, which are first injected slowly intravenously (0.1 mg / kg), and then used inside at a daily dose of 1 mg / kg. Patients with tetralogy of Fallot should not be prescribed digoxin, since it increases the inotropic function of the myocardium, increases the probability of spasm of the infundibular part of the right ventricle.

Palliative surgery - the imposition of inter-arterial anastomoses of various types (usually a modified subclavian-pulmonary anastomosis) is necessary when cessation and cyanotic attacks are not stopped by conservative therapy, as well as in poor anatomical variants of blemish (pronounced hypoplasia of the pulmonary branches). Palliative variants of operative intervention include balloon dilatation of the stenotic pulmonary valve, reconstruction of the excretory part of the right ventricle without closure of the defect of the interventricular septum. The goal of these measures is to reduce arterial hypoxemia and stimulate the growth of the pulmonary arterial tree. In the most commonly used technique, the application of subclavian pulmonary anastomosis according to BlalockTaussig, a subclavian artery is connected to a unilateral pulmonary artery by means of a synthetic implant. It is preferable to carry out a radical operation immediately.

Radical surgery is usually performed at the age of 6 months to 3 years. The long-term outcome of the intervention is worse when performed at an older age (especially after 20 years).

The complete correction consists of closing the defect of the interventricular septum with a patch and widening the exit from the right ventricle (stenotic area of the pulmonary artery). The operation is usually performed electrically in the first year of life, but in the presence of symptoms it can be performed at any time after 3-4 months of life.

All patients, regardless of whether a correction of the defect was performed or not, should receive endocarditis prophylaxis before dental or surgical procedures, in which bacteraemia may develop.

Perioperative lethality is less than 3% with uncomplicated Fallot tetrad. If the tetralogy of Fallot is not operated, up to 5 years, 55% survive and up to 10 years - 30%.