Tetralogy of Fallot

Introduction to tetralogy of Fallot Fallot tetralogy is a common congenital heart vascular malformation, ranking first in purpuric congenital heart disease. The pathological anatomical features of the disease have four points: 1 pulmonary artery stenosis; 2 ventricular septal defect; 3 liter aortic opening offset to the right; 4 right ventricular centripetal hypertrophy. In 1944, BlaloCk and Taussig realized that the main pathophysiological changes in the quadruple syndrome were insufficient blood flow in the pulmonary circulation, decreased arterial oxygen levels, and caused cyanosis and death. basic knowledge The proportion of illness: the probability of illness in infants and young children is 0.36% Susceptible population: The disease is a congenital disease, and 90% of patients will die. Mode of infection: non-infectious Complications: cerebral thrombosis, brain abscess

The cause of tetralogy of Fallot

Cause

VanPraagh believes that the four malformations of tetralogy of Fallot are the consequences of right ventricular funnel or cone dysplasia, that is, when the embryo is not rotated in the fourth week of the embryo, the aorta remains on the right side of the pulmonary artery, and the cone is forward. Displacement, the sinus chamber spacing from the normal position failed to close, thus forming a hypoplastic apical portion and an infraorbital ventricular septal defect, ie, a perimembranous ventricular septal defect. If the pulmonary artery is underdeveloped, or the cone is completely absent, a subvalvular ventricular septal defect, ie, a dry type ventricular septal defect, is formed. At present, the cause of the disease is not clear, and it may be related to fetal intrauterine virus infection, such as rubella virus syndrome, or mother alcoholism, medication during pregnancy, such as amphetamine, estrogen, progesterone, anticonvulsant drugs and other factors.

Fallot tetralogy prevention

1, age-appropriate marriage, do not marry early, early pregnancy, do not be too late marriage, late pregnancy, to avoid the baby's congenital deficiency, planned eugenics.

Complications of tetralogy of Fallot Complications, cerebral thrombosis, brain abscess

The most common complications are cerebral thrombosis (erythrocytosis, increased blood viscosity, stagnation of blood flow), brain abscess (bacterial thrombosis) and subacute bacterial endocarditis, and active surgical treatment. Children will also have some postoperative complications:

1. Pulmonary complications

The main pathological changes of F4 are right ventricular outflow tract stenosis and high ventricular septal defect leading to right to left shunt, pulmonary blood flow reduction, blood viscosity, oxygen transport disorders, the main factor affecting the treatment effect of F4 is pulmonary artery development, especially around Pulmonary artery branches and even distal branches are small, the curative effect is poor, preoperative anemia, pulmonary vascular and pulmonary dysplasia, blood viscous and less pulmonary blood can cause alveolar degeneration and pulmonary capillary microthrombus formation, intraoperative pulmonary vascular side Excessive and overfilling, poor pulmonary venous return, formation of perfused lung, right ventricular outflow tract dredge, pulmonary blood increased significantly, postoperative pulmonary blood perfusion increased significantly, plus infants and lungs and bronchial brittle, lumen Small, more secretions, easy to block the lumen, pulmonary complications often occur after surgery, and become one of the main causes of early death after F4, in order to prevent pulmonary complications, more than the medial branch of the lung The method of deep low temperature and low flow is adopted to ensure the smooth flow of the left heart, to reduce the perfusion of the collateral circulation to the lungs, to strictly control the amount and quality of the infusion (blood), and the red blood cells during the pre-filling of the extracorporeal circulation. The pressure should not be lower than 20%, the colloid osmotic pressure should not be lower than 113kPa, prevent the lung from seeping out, the temperature difference between cooling and rewarming should not exceed 10 °C, continuous static lung expansion and intermittent positive pressure lung expansion in the flow, postoperative Ventilator PEEP015113kPa, pulmonary physical therapy, nebulization, full suction, some children may have asthma or laryngeal edema after extubation, should be given timely inhalation and bronchodilator, aminophylline or asthma The effect is good.

2, complete atrioventricular block

III degree atrioventricular block is a common complication after F4 radical surgery. Due to direct intraoperative trauma, improper traction or suture position, intraoperative hypothermia, hypoxia-ischemia, etc., complete atrioventricular block However, most of them are transient. The sinus rhythm can be restored after rewarming and removal of the vena cava drainage tube. In the case of ineffective, isoproterenol (5g/ml) can be administered intravenously, 5~10g intravenously, and temporary cardiac pacing and hormone can be used. treatment.

3, low cardiac output syndrome

Due to excessive complexity of the deformity, unsatisfactory correction of surgical malformation, residual leakage of the ventricular septal defect or insufficient outflow tract and pulmonary stenosis, excessive ventricular incision injury, right atrial function, aortic occlusion time is too long, poor myocardial protection during surgery Left ventricular hypoplasia, low blood pressure at room temperature and other factors, prevention is to avoid the above-mentioned causes, strict observation after surgery, early treatment, in the case of exclusion of hypovolemia or pericardial tamponade, can be used to expand blood vessels such as sodium nitroprusside Drugs, supplemented with dopamine, isoproterenol, etc., to reduce the load before and after the heart, enhance myocardial contractility, control low cardiac output.

4, bleeding bleeding

F4 patients due to circumflex circulation, coagulation mechanism and long-term extracorporeal circulation time, etc., resulting in increased bleeding opportunities, in addition to blood loss can also cause pericardial tamponade, affecting heart function, and even life-threatening, prevention and treatment methods are as short as possible During the extracorporeal circulation time, ACT monitoring was strictly adopted. The bleeding was carefully stopped before the end of the operation. The drainage tube was kept open after operation, and the amount of drainage fluid was closely observed. If necessary, the chest was opened to stop bleeding.

5, systemic capillary leak syndrome

Newborns and small infants often have leakage after cardiopulmonary bypass, which may be related to the release of inflammatory mediators and capillary endothelial damage. The clinical manifestations are severe edema of the whole body, massive exudation of the thoracic and abdominal cavity, and often require a larger dose of catecholamines. Drugs and the input of a large amount of colloidal fluid to maintain blood pressure, there is no effective prevention method, the application of hormones may increase capillary stability, but can not prevent leakage, such patients need to determine plasma protein at any time, so that total protein is maintained 7 ~ 8mmol / L, hemoglobin 12 ~ 14mg / L.

Symptoms of tetralogy of Fallot Common symptoms Dyspnea purpura heart failure clubbing (toe) systolic tremor cardiogenic dyspnea purpura and blood hypoxia systolic murmur infectious neoplasm

The most common clinical symptoms of tetralogy are purpura and blood hypoxia. The time and severity of clinical symptoms depends on the degree of right ventricular outflow obstruction and the amount of pulmonary circulation blood flow. Because the arterial catheter is not closed shortly after birth, Pulmonary circulation blood flow can come from the patent ductus arteriosus, so it is often not clinically present with purpura. In most cases, purpura begins to appear after several weeks or months after the birth of the arterial catheter, and gradually increases, but the right ventricular outflow tract. Obstructive lesions are severe, such as pulmonary atresia, diffuse dysplasia of the outflow tract, and funnel, pulmonary valve annulus, multiple severe stenosis of the pulmonary valve, then purpura after birth, right ventricular outflow obstruction is light, right to left In cases with low blood flow, the degree of purpura is light. If the blood flow in the ventricle is mainly from left to right, it may not present purpura, eating, crying, purpura is aggravated during activity, and breathing difficulties occur. Children are happy to take a squat position. It can reduce the venous return flow of the lower extremities, increase the circulation resistance, and increase the blood flow of the lungs. Oxygen saturation increased, cyanosis and dyspnea reduced.

When the funnel is stenosis, the stenosis is aggravated, and the sudden decrease of pulmonary blood flow can cause hypoxic episodes, which may cause difficulty in breathing, fainting and convulsions. In severe cases, it can be fatal. When the climate is hot and the body temperature rises, it is more likely to attack. Jet systolic murmur often weakened or disappeared, morphine 0.2mg/kg intramuscular injection, or propranolol 2.5mg/kg daily can alleviate hypoxic attack, a small number of cases due to ventricular septal defect, 1~2 after birth When the monthly pulmonary vascular resistance is reduced, the left-to-right sub-flow increase leads to pulmonary circulatory congestion, which may present symptoms of heart failure clinically. However, after 6 months of birth, purpura is gradually aggravated, the degree of purpura is heavy, and the number of red blood cells is significantly increased, and cerebral blood vessels may form. Thrombosis causes hemiplegia or brain abscess. In the case of body water loss, cerebral thrombosis is more likely to occur. In severe cases of older purpura, the bronchial artery collateral circulation is abundant. Once rupture occurs, a large amount of hemoptysis can be caused.

Examination of tetralogy of Fallot

The following examination methods are helpful for the diagnosis of this disease:

1. Chest X-ray examination: typical cases of quadruple disease show that the heart does not increase, the lung field is abnormally clear, the vascular shadow is scarce, the total pulmonary artery is smaller, the left edge of the heart is flat or concave, such as the third ventricle is larger The left marginal pulmonary artery segment protruded, and the apex of the left ventricular hypertrophy caused the apex to rise upward. On the posterior anterior radiograph, the heart shadow was shoe-shaped, and about 1/4 of the aortic arch was located on the right side.

2, ECG examination: showing right ventricular hypertrophy and strain, the right axis of the motor axis, the right pre-cardiac lead lead R wave significantly increased, T wave inverted, some patients with the first and second leads showed right atrial hypertrophy P wave, the left front chest lead does not show Q wave, and the R wave voltage is low.

3, right heart catheterization: right heart catheterization showed increased right ventricular pressure, can reach the left ventricular pressure level, cardiac catheter can directly enter the aorta from the right ventricle indicating the presence of ventricular septal defect and aortic riding, due to right ventricular outflow tract And / or pulmonary stenosis showed a contraction pressure gradient between the right ventricle and the pulmonary artery, analysis of the shape of the pressure curve can identify the location of the stenosis, type and presence of the third ventricle, arterial oxygen saturation decreased, generally below 89%, exercise After further reduction, the right heart catheter was injected into the right ventricle and the pulmonary artery respectively, and the indicator dilution curve in the peripheral arteries showed that the indicator of right ventricular injection appeared early, and the curve descending showed a bimodal right-to-left shunt. The curve, the indicator injected into the pulmonary artery, was recorded to the normal curve.

4, echocardiography: section echocardiography is very valuable for the diagnosis of tetralogy, can directly show the right ventricular wall thickening, right ventricular outflow tract showing tubular stenosis or the formation of the third ventricle, pulmonary stenosis; pulmonary artery The caliber is smaller than the aorta, the echo of the ventricular septum is interrupted, and the anterior wall of the aorta is moved to the right, riding over the ventricular septum.

5, selective right ventriculography: the four cases of tetralogy of Fallot must be selected for selective right ventricular angiography before surgery, a cardiac catheter injection of contrast agent in the right ventricular cavity, continuous X-ray film examination can show pulmonary artery and At the same time, the aorta develops simultaneously and the aorta rides. At the same time, the contrast agent enters the left ventricle from the right ventricle through the ventricular septal defect. The angiographic examination can still show the location and extent of the right ventricular outflow tract and/or pulmonary stenosis, and understand the pulmonary artery development. And measure the diameter of the total trunk of the pulmonary artery and the ascending aorta, and calculate the ratio between the two.

6, retrograde aortic angiography: can show patent ductus arteriosus, bronchial artery collateral circulation development and aortic valve opening and closing function, McGoon measurement of left and right pulmonary artery and diaphragmatic plane descending aorta diameter, such as left and right pulmonary artery diameter The ratio of the sum to the diameter of the descending aorta is greater than 2.0, indicating that the pulmonary blood flow is not obstructed.

7, blood test: red blood cell count, hemoglobin and hematocrit are significantly increased, severe purpura case red blood cell count up to 10 million, hemoglobin 258%, hematocrit is generally 50 ~ 70%, but can also be as high as 90%.

Diagnosis and diagnosis of tetralogy of Fallot

Physical growth is slower. The face, lips, tongue, and eyelid combined with the membrane are obviously purpura. Children's patients with clubbing (toes) are common. The heart sound zone does not expand, and the left front chest can be raised. The systolic murmur caused by the narrowing of the right ventricular outflow tract can be heard between the 2nd and 3rd ribs of the left sternal border, which may be accompanied by tremor. The degree of stenosis is heavy, the blood flow to the aorta is increased in the right ventricle, and the blood flow in the pulmonary arteries is correspondingly reduced, and the noise is reduced, which is short. The systolic murmur of the pulmonary atresia may disappear and be replaced by a continuous murmur produced by the collateral circulation or patent ductus arteriosus. The second heart sound in the pulmonary valve area is weakened or normal, and sometimes a single loud heart sound from the second heart sound of the aortic valve.

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