What is Tetralogy of Fallot?

Tetralogy of Fallot (TOF) is a common congenital heart malformation. Its basic pathology is ventricular septal defect, pulmonary stenosis, aortic striding, and right ventricular hypertrophy. Tetralogy of Fallot ranks first among children with cyanotic heart malformations. The prognosis of children with tetralogy of Fallot mainly determines the degree of pulmonary artery stenosis and collateral circulation. 25% to 35% of severe cases die within 1 year of age, 50% of patients die within 3 years of age and 70% to 75% die By the age of 10, 90% of patients die. Mainly due to chronic hypoxia, erythrocytosis, leading to secondary myocardial hypertrophy and heart failure and death.

Basic Information

nickname

Tetralogy of Fallot, tetrad of cyanosis, tetrad of congenital cyanosis

English name

tetralogy of Fallot

English alias

Fallot tetrad

Visiting department

Cardiology, Pediatrics

Common locations

heart

Common causes

Embryonic abnormalities

Common symptoms

Cyanosis, dyspnea and hypoxic attacks, squatting

Contagious

no

Causes of tetralogy of Fallot

VanPraagh believes that the four abnormalities of tetralogy of Fallot are caused by dysplasia of the right ventricle funnel or cone, that is, the arterial trunk does not rotate in the reverse direction at the fourth week of the embryo, the aorta remains on the right side of the pulmonary artery, and the cone septum moves forward. Position, the sinus ventricular septum of the normal position could not be aligned, thus forming an underdeveloped funnel and subsacral ventricular septal defect, that is, a permembranous ventricular septal defect. If the pulmonary artery cone is underdeveloped, or the cone portion is completely absent, a subpulmonary valve type ventricular septal defect is formed, that is, a dry subventricular type septal defect.

Clinical manifestations of tetralogy of Fallot

The prognosis of children with tetralogy of Fallot disease mainly depends on the degree of pulmonary artery stenosis and collateral circulation. 25% to 35% of patients with severe tetralogy die within 1 year of age, 50% of patients die within 3 years of age, and 70% to 75%. % Died within 10 years of age, 90% of patients died, mainly due to chronic hypoxia, erythrocytosis, leading to secondary myocardial hypertrophy and heart failure and death.

Symptoms

(1) Hair cyanosis occurs mostly 3 to 6 months after birth, and a few do not appear until childhood or adulthood. The cyanosis worsens during exercise and crying, and decreases when calm.

(2) Dyspnea and hypoxic episodes begin to appear 6 months after birth. Due to tissue hypoxia, poor endurance of activity, shortness of breath, and severe cases may occur hypoxic episodes, loss of consciousness or convulsions.

(3) Crouching is a clinically characteristic posture for children with tetralogy of Fallot. Squats can relieve breathing difficulties and cyanosis.

2. Signs

Children with stunted growth and development often have club-like fingers and toes, which usually occur months or years after the onset of cyanosis. Rough jet-like systolic murmurs can be heard in the 2nd to 4th intercostal space of the left margin of the sternum, often accompanied by fine tremor during systole. Very severe right ventricular outflow obstruction or pulmonary arterial atresia may be free of cardiac murmurs. When there is a continuous murmur in the front or back of the chest, it indicates that there are abundant collateral blood vessels, and the second heart sound of the pulmonary valve is significantly weakened or disappeared.

Tetralogy of Fallot

Laboratory inspection

Red blood cell counts, hemoglobin, and hematocrit often increase. Hemoglobin can reach 200 to 250 g / L in severe cases. Arterial blood oxygen saturation decreased significantly, mostly between 65% and 70%. Platelet counts decrease and prothrombin time prolongs. Urine protein can be positive.

2. ECG

Right axis, right atrial hypertrophy, right ventricular hypertrophy. About 20% of patients develop incomplete right bundle branch block.

3. Chest X-ray

The left heart waist is sunken, the apex is round and blunt, and the aortic node protrudes, showing a "boot-shaped heart". The pulmonary field is slender. Pulmonary arterial depression is not obvious in light patients, and the pulmonary field vessels are slightly reduced or normal.

4. Echocardiography

Echocardiography is of great value in the diagnosis of tetrad and the choice of surgical methods. The type and size of ventricular septal defect can be observed from different aspects, the aorta rides above the ventricular septum, the location and degree of pulmonary artery stenosis, and the mitral The fibrous continuity of the aortic valve and the aortic valve. Color Doppler can display the shunt from the right ventricle to the aorta, and measure left ventricular volume and function. Ultrasound can also show the presence of other combined deformities. If peripheral pulmonary stenosis is suspected, cardiovascular angiography should be performed.

5. Cardiac Catheter and Cardioangiography

Examination of the right ventricle catheter can measure the peak systolic pressure of the two ventricles, the pressure gradient curve between the pulmonary artery and the right ventricle, and understand the right ventricular outflow tract and pulmonary stenosis. Right ventricular angiography can show the type and degree of pulmonary artery stenosis, the location and size of ventricular defects, and the development of peripheral pulmonary blood vessels. Left ventricular angiography can show the development of the left ventricle.

Tetralogy of Fallot

According to the medical history, physical examination combined with ECG and chest X-ray changes. Pluripotency prompts the diagnosis of tetralogy of Fallot. Most children with tetralogy of Fallot can be diagnosed by echocardiography and have severe pulmonary dysplasia. Cardiovascular angiography should be performed in patients with pulmonary valve atresia or pulmonary artery absent to understand the development of dilute blood vessels.

Differential diagnosis of tetralogy of Fallot

1. Fallot Triad

The onset of cyanosis is relatively late, squatting is rare, and there is a jet systolic murmur in the second intercostal space of the left margin of the sternum, which is long and loud. The chest radiograph showed that the right ventricle and right atrium were enlarged, and the pulmonary artery segment was prominent. Echocardiography can be identified.

2. Eisenmenger syndrome

The cyanosis appeared later and was lighter. The X-ray showed that the blood vessels around the lung field were small and the hilar vessels were thick and root-shaped. The right heart catheterization and echocardiography showed a significant increase in pulmonary artery pressure.

3. Double outlet of right ventricle

Both the aorta and pulmonary arteries originate from the right ventricle, and in some cases, the clinical manifestations are similar to those of tetralogy. Echocardiography and right ventricular angiography can be distinguished.

4. Aortic dislocation

The heart is larger and the blood vessels in the lungs are more textured. The differential diagnosis depends on cardiovascular angiography. It is worth noting that the distinction between SDtype quadruple disease and SDL type anatomic correction of aortic ectopic: Tetralogy has a normal pulmonary artery cone without subaortic cone, and SDL type anatomical correction of aortic ectopic has subaorta Cone or double cone under the aorta and pulmonary artery. The aortic relationship of the SDI tetrad is normal inversion, while the SDL anatomic correction of aortic ectopic is similar to the complete aortic translocation, and the aorta is in the anterior left or side by side relationship.

Tetralogy of Fallot

There are several methods for clinical surgery:

1. Quadruple Surgery

The supine position, general anesthesia, and mid-thoracic incisions are generally advocated by moderate hypothermia extracorporeal circulation, and neonates are advocated by deep hypothermia and low-flow extracorporeal circulation. Generally, 4 cold-blooded cardioplegia was used to induce cardiac arrest for coronary myocardial perfusion for myocardial protection. Intracardiac corrective surgery includes repair of ventricular septal defect and proper removal of right ventricular outflow tract obstruction.

2. Palliative surgery

Pulmonary vascular development is poor, left ventricular development is small, and infant coronary artery malformations affect the use of right ventricular outflow tract patches, all should undergo palliative surgery, and then undergo secondary correction surgery. Choices of palliative surgery: For older children, subclavian artery-pulmonary anastomosis or right ventricular outflow tract patch widening is more common, which is suitable for cases where the pulmonary arteries on both sides are too narrow. Infants within 3 months were treated with ascending aorta-pulmonary anastomosis or central shunt.