Simple pulmonary stenosis in children

Introduction to simple pulmonary stenosis in children Simple pulmonary stenosis refers to a congenital malformation in which the pulmonary valve or funnel is narrow and the septum is intact. Pulmonary artery stenosis is the main lesion of right ventricular outflow obstruction. The stenosis can be in the lower part of the pulmonary valve, the valve, the total trunk of the pulmonary artery and the branches. Among them, simple pulmonary valve stenosis is the most common, accounting for 80% to 90%. basic knowledge The proportion of illness: 0.002% Susceptible people: children Mode of infection: non-infectious Complications: arrhythmia heart failure brain abscess infective endocarditis

Causes of simple pulmonary stenosis in children

(1) Causes of the disease

During the first 3 months of embryogenesis, the fetus can cause pulmonary artery stenosis for a variety of reasons. Two important reasons worth pointing out are the environmental factors, namely rubella syndrome, and the other is family genetic factors. If the mother suffers from rubella during the first 3 months of pregnancy, the fetus can develop rubella syndrome, which is manifested as cataract, deafness and cardiovascular malformation. The most common cardiovascular malformation is pulmonary stenosis or pulmonary valve stenosis. Familial pulmonary stenosis has recently been found, with a prevalence of 2.9% among brothers; in other syndromes such as Noonan syndrome, pulmonary stenosis may also be present, but the etiology of most patients has not been confirmed. The aorta semilunar valve is developed from the bulge of the arterial trunk and the intervening bulge. The anterior lobe of the pulmonary valve originates from the left interstitial uplift, and the posterior left and right lobe are from the left lower and upper right arterial trunk ridges, respectively. The leaflet joint is formed by the separation of these embryonic tissues. The mechanism of formation of pulmonary stenosis is unclear. If there are no traces of leaflet joints on the leaflets, it is presumed that there is no separation between the arterial trunks or interstitial bulges in the early stages of embryonic development. If there are connective tissue bundles or stitches on the leaflets, it may be caused by fusion between the leaflets in the late embryonic development. It is also believed that fetal endocarditis is associated with the occurrence of valvular stenosis.

(two) pathogenesis

Pulmonary artery stenosis includes pulmonary valve, pulmonary funnel and pulmonary trunk and its branch stenosis, the clinical incidence rate accounts for 4% to 10% of congenital heart disease, and the ratio of male to female is roughly equal. "Single pulmonary stenosis" refers to intact ventricular septum. Case, but may be associated with patent foramen ovale or atrial septal defect. According to Abbott statistics, pulmonary stenosis with open foramen ovale accounted for about 2.5%.

Pathological anatomy

When the normal fetus is born, the pulmonary artery mouth is about 0.5cm2, which gradually increases with the growth and development, up to 2.0cm2/m2 at the time of maturity, and the effective pulmonary artery mouth must be reduced by about 60% before the obvious hemodynamic changes occur. Clinically, the most common valvular stenosis is stenosis, accounting for about 75%. It is often caused by the fusion of the valve in the embryo and the late valve. The trifoliate valve of the pulmonary valve fuses into a cone shape, bulging into the pulmonary artery, leaving a small hole in the center. The diameter varies from 2 to 10 mm. The smallest one is 1-3 mm. The valve is soft and thin. The valve is often in the center. As the age increases, the valve becomes thicker and thicker. The valve is not in the center. In some cases, the valve has only two leaves. The funnel is about 15% narrow. It can be located in the upper, middle and lower parts of the right ventricular outflow tract. It can be muscle type, that is, the whole funnel muscle is thickened to form a narrow and long passage. It can also be a diaphragm type, that is, A partial fibrous septum is formed in the funnel portion, which is annularly narrowed, and a part of the funnel portion or the funnel portion is separated from the right ventricle to form a two-chamber right ventricle. The funnel portion is narrowed together with a valve-type stenosis, which is called mixing. Narrow type, About 10%, the cause of pulmonary stenosis is mainly due to intrauterine infection of the embryo, especially caused by rubella virus infection. Pulmonary artery stenosis may involve part or all of the common pulmonary artery, and may also extend to the left and right pulmonary artery branches, or multiple The involvement of the peripheral pulmonary artery branches, or the involvement of the total trunk and peripheral secondary artery or small artery branch, the wall of the pulmonary artery after stenosis is often thin and dilated, called stenosis and expansion, more common in valve-type stenosis, and in the funnel-shaped stenosis Less common, the cause of post-stenosis expansion may be caused by defects in the development of the pulmonary artery itself or blood flow impinging on the pulmonary artery. The right ventricular hypertrophy and the right atrium are also large in this disease.

2. Pathophysiology

Due to stenosis of the pulmonary artery, excessive contraction of the right ventricle, increased right ventricular systolic pressure, part of the pressure is consumed to overcome the resistance of the stenosis, causing the pulmonary artery pressure to be lower than the right ventricular pressure, resulting in a pressure gradient between the right ventricle and the pulmonary artery, however, This disease is different from the tetralogy of Fallot, and it can maintain a certain amount of cardiac output. The patient also has a certain ability to move. This compensation is achieved by increasing the right ventricular pressure. Generally, the maximum systolic transvalvular pressure difference is 50 to 80 mmHg (6.7 to 10.6 kPa), or right ventricular maximum systolic pressure between 75 and 100 mmHg (10.0 to 13.3 kPa) suggesting moderate stenosis; below or above this range, respectively, mild or severe stenosis, Severe cases of right ventricular systolic blood pressure up to 150mmHg (33.3kPa), children with moderate or higher stenosis with age, the degree of stenosis is more obvious, valve fiber thickening, right ventricular outflow tract progressive thickening, resulting in funnel Stenosis, such as right ventricular decompensation, diastolic blood pressure is also increased, right atrial pressure is also increased, even in the atrial level, right to left shunt and cyanosis, it is called Fallot triad, advanced case Heart failure.

Prevention of simple pulmonary stenosis in children

Ask family history to understand the genetic situation, investigate the impact of environmental factors to explore the cause of congenital heart disease, Shaw through the investigation of the address to understand the environmental teratogenic factors that the pregnant mother may be exposed, the address of the mother's production is sometimes used to represent The address of the early pregnancy was estimated by environmental factors. The authors investigated the address of the mother at the time of pregnancy and birth. About 24.8% of the mothers moved between the beginning of pregnancy and production, so observing the production address may reduce congenital malformation and the mother's exposure to the environment. The positive result of the association should be investigated in the environment of the address at the time of pregnancy. Schwanitz advocated that the detection of cardiac malformation before birth can be used as an indication for chromosomal examination. The authors mentioned that 588 fetuses were diagnosed with growth retardation and/or congenital malformation before birth. A chromosome examination was performed, and 116 (19.7%) of these cases were confirmed to have chromosomal abnormalities. Among these malformed fetuses diagnosed before birth, 102 (17.3%) of the fetuses with cardiac malformations, therefore, cardiac malformations For the most common malformations, 41 fetuses (40.2%) have chromosomes in the fetus that was diagnosed with a cardiac malformation before birth. Chang (trisomy 21 to 18 and is most common) syndrome.

In addition to monitoring the fetus, the mother's disease should also be monitored. Breton reported that the mother had phenylketonuria, and the plasma of phenylalanine continued to increase during pregnancy, and the child born had a cardiac malformation, Breton reported. A child's coronary artery abnormality originates from the right pulmonary artery, ventricular septal defect, fetal growth retardation and facial deformity. The phenylalanine in the mother's plasma continues to increase during pregnancy. The cardiac malformation is diagnosed 8 months after birth, and its developmental delay It is caused by maternal phenylketonuria, which can also cause ventricular septal defect and coronary artery malformation. The authors suggest that if the mother begins a dietary treatment before pregnancy, it may prevent fetal damage, so if there is a cause In-depth understanding, before pregnancy, pregnancy can be used to monitor maternal disease and fetal malformation of pregnant mothers and fetuses. If possible, try to prevent fetal congenital malformation, but from genetics and environment From the point of view of harm, the cause of congenital heart disease is not fully understood, and most of them are powerless in prevention. Explain the cause and it is not completely clear, most of them can't do anything about prevention. Therefore, explaining the cause and fundamentally preventing the occurrence of congenital heart disease is still an extremely difficult task. It is still necessary for scientists and basic scholars to work together to explore.

Complications of simple pulmonary stenosis in children Complications arrhythmia heart failure brain abscess infective endocarditis

Can be complicated by heart failure or arrhythmia, can cause brain abscess, easy to suffer from lung infection, and infective endocarditis.

Symptoms of simple pulmonary stenosis in children Common symptoms Edema systolic murmur labor dyspnea clubbing (toe) palpitations ascites heart failure right heart failure ventricular hypertrophy pulmonary valve area audible...

General symptoms

The severity of symptoms is related to the degree of stenosis of the pulmonary artery. The mild stenosis is mostly asymptomatic and has good growth and development. It is often diagnosed by heart murmur due to physical examination. The moderate stenosis may have palpitations. After tiring, the dyspnea is difficult. There are patent foramen ovale, in addition to breathing difficulties, there may be symptoms such as bruising, clubbing (toe) and heart failure.

2. Cardiac examination

The heart size is usually normal in mild stenosis, and the right ventricle is enlarged in moderate and severe stenosis, which can form anterior ventricular bulging. Pulmonary stenosis has systolic tremor in the second intercostal space on the left sternal border, and can hear rough The longer the systolic murmur, the murmur of the funnel is the loudest in the 3rd and 4th ribs, and the murmur is rhombic in the heart sound map. The loudness of the murmur gradually increases with the stenosis, and the maximum amplitude of the rhombic noise As the degree of stenosis increases, the gradual self-contraction moves to the middle and later stages. The second heart sound of the pulmonary artery is reduced and the degree of division is also gradually changed with mild, moderate, and severe stenosis. In addition, the light, medium, and severe stenosis are often found on the left sternal border. In the 2nd and 3rd intercostals, the early jetting sound is heard. If the right heart is exhausted, the liver, ascites and edema can be seen. However, due to the decrease of blood flow in the lung, pulmonary congestion is not found.

Examination of simple pulmonary stenosis in children

Concurrent infections include increased white blood cells and neutrophils, anemia, and decreased hemoglobin (Hb).

X-ray inspection

The size of the heart gradually increases with the increase of stenosis. Generally, the heart does not increase when the stenosis is mild. If it increases, the right ventricle increases. The right atrium can also be slightly larger, but the left ventricle is not large. In addition, the pulmonary artery The trunk and left pulmonary artery are accompanied by more obvious pulsation due to the expansion of the stenosis, and the lung texture in the lung field is reduced. The contrast between the two should be in sharp contrast. This is a characteristic of the disease, but in the case of stenosis of the funnel, The trunk of the pulmonary artery is concave.

2. ECG

The judgment of the degree of stenosis is very meaningful. Except for the mild stenosis ECG, normal right ventricular hypertrophy, right axis or right incomplete right bundle branch block, right ventricular hypertrophy and stenosis are often In contrast, in patients with severe stenosis, if the right ventricular pressure exceeds 100 mmHg, the ECG has at least one of the following three points:

(1) RVl>20mv.

(2) P wave high tip, showing right atrial hypertrophy.

(3) ST-segment shift in each lead, II, avF and V1 to V4 lead T-wave inversion, showing myocardial strain.

3. Echocardiography: In patients with mild stenosis, pulmonary valve activity is normal. When the stenosis is moderate or severe, two-dimensional echocardiography combined with continuous wave Doppler can accurately assess the stenosis and its severity, right atrium and right ventricle. The inner diameter of the right ventricle is widened, the free wall of the right ventricle and the interventricular septum are thickened, the pulmonary valve is thickened, and the opening is restricted to a round shape. The severe stenosis can be seen that the pulmonary valve is open early in the systolic phase, and the right ventricular outflow tract is narrow in the narrow funnel. The diameter of the main pulmonary artery and its left and right branches can also be measured. In addition, continuous Doppler exploration can be used to estimate the transvalvular pressure difference based on the modified Bernoulli equation.

4. Cardiac catheterization is helpful for diagnosis. The distal pressure of the pulmonary artery stenosis is reduced, but the right ventricular pressure at the proximal end of the stenosis is significantly increased. When the cardiac catheter is withdrawn from the pulmonary artery to the right ventricle, the systolic pressure in the pressure curve suddenly increases. The diastolic pressure is unchanged, showing a narrowing of the pulmonary valve (Fig. 5); if there is a third pressure wave between the pulmonary artery and the right ventricle, the systolic pressure is the same as the pulmonary artery and the diastolic pressure is equal to the right ventricle, which means the funnel Stenosis (Fig. 6), the right atrial pressure can also be increased in severe stenosis, the blood oxygen content of each compartment and large blood vessels in the heart is within the normal range. If the foramen ovale is not closed, the catheter can pass the patent foramen from the right atrium. Hole into the left atrium.

5. CT and MRI: simple pulmonary stenosis usually does not require CT and MRI, but if accompanied by peripheral pulmonary stenosis or right ventricular dysfunction, CT and MRI are helpful, MRI spin echo T1W image is better The pulmonary valve is thickened, the pulmonary artery trunk and the left pulmonary artery are proximally dilated, and the right ventricle is hypertrophic. The gradient echo film sequence shows a low-signal abnormal blood flow to the pulmonary artery trunk. The gradient echo movie sequence can also be very accurate. Right ventricular end-diastolic volume and right ventricular ejection fraction were measured, and contrast-enhanced magnetic resonance angiography and multi-slice spiral CT showed better peripheral pulmonary stenosis.

6. Cardioangiography: Cardiac angiography of pulmonary stenosis is mainly for right ventricular angiography, which can show the location and severity of pulmonary stenosis. If the stenosis is stenosis, the stenotic valve mouth is fish-like and has pulmonary stenosis. The expansion of the right pulmonary artery is sometimes seen, and severe pulmonary stenosis is often accompanied by secondary right ventricular systolic stenosis.

The catheter is selected from the NIH right heart angiography catheter and placed at the tip of the right ventricle. The left or right anterior oblique position is selected. When the tricuspid valve has obvious reflux, the common catheter is difficult to place in the right ventricle. The venous route was inserted for right ventricular angiography, and the contrast agent was adjusted with Omega Parker 350, 1 to 1.5 ml/kg, according to the severity of pulmonary stenosis and tricuspid regurgitation.

The position of the projection is usually on the left side. This angle is used to observe the thickening of the pulmonary valve. The expansion of the pulmonary artery and the left stenosis of the left pulmonary artery is clear. However, when the tricuspid valve has obvious reflux, it flows back into the right atrium at the lateral position. The contrast agent can overlap with the development of the pulmonary valve site, and in the right anterior oblique position, even if the contrast agent flows back to the right atrium, the two parts can be separated, which is convenient for displaying the pulmonary valve structure and measuring the diameter of the annulus.

Cardiovascular angiography should determine the type of pulmonary stenosis, observe the thickness of the pulmonary valve, the activity of the valve leaflets, whether there is a jet, the presence or absence of pulmonary trunk expansion, typical pulmonary stenosis, limited opening of the valve opening during right ventricular angiography, valve Appeared in the shape of a apex or a fish mouth, the diameter of the annulus is normal, the jet of the valve is obvious, the trunk of the pulmonary artery is dilated, the valvular stenosis is stenosis, the valve is thickened, the nodular filling defect, the valve is not active, and the valve is not present. The shape of the apex is small, the diameter of the annulus is smaller than normal, and there is no obvious jet sign at the valve orifice. The trunk of the pulmonary artery has no obvious stenosis and then expands.

Cardiac angiography of pulmonary stenosis should also pay attention to the observation of pulmonary artery branches, right ventricle and tricuspid valve, to understand the presence or absence of right ventricular volume reduction, right ventricular dysfunction, secondary right ventricular stenosis and pulmonary artery stenosis (Figure 9 ), and should pay attention to the presence or absence of tricuspid regurgitation, atrial level with or without shunt.

Diagnosis and differentiation of simple pulmonary stenosis in children

diagnosis

Rough systolic murmur in the pulmonary valve area, P2 weakened or disappeared, X-ray or ECG changes in right ventricular hypertrophy may indicate diagnostic clues, but need to be differentiated from atrial septal defect, ventricular septal defect, primary pulmonary artery dilation, etc. In addition to pulmonary artery expansion, primary pulmonary artery dilatation, systolic murmur, more tremor, P2 normal, cardiac catheter pressure and blood gas analysis are normal.

Differential diagnosis

Simple mild pulmonary stenosis needs to be distinguished from ventricular septal defect. The former has reduced pulmonary blood volume, the latter increases, and the location and nature of the noise are different. The former murmur is jet-shaped on the heart sound map, and the latter murmur is full contraction. Period, in the heart sound map is consistent, cardiac catheterization can help identify, severe pulmonary stenosis with cyanosis should be differentiated from tetralogy of Fallot, the former cyanosis appears later, the pulmonary artery systolic murmur is stronger, the second Heart sounds have divisions, but they are weak, and there are often pulmonary artery segments on the X-ray.

1. Identification of pulmonary stenosis and other cardiovascular malformations

(1) differentiation from primary pulmonary dilatation: primary pulmonary artery dilatation, and mild pulmonary stenosis is extremely difficult to identify, the former may have a mild early jet systolic murmur, but not as rough as the latter, and very Less accompanied by tremor, ECG and vector ECG are normal, if there is a right ventricular hypertrophy suggesting pulmonary stenosis, echocardiography can be identified, if necessary, right heart catheterization and cardiovascular angiography should be performed to confirm the diagnosis.

(2) Differentiation from atrial septal defect: The systolic murmur of the left sternal border of patients with atrial septal defect is not as loud and rough as that of patients with pulmonary stenosis, and usually without tremor; the second sound of pulmonary artery is fixed and split, but the division is not as good as pulmonary stenosis. Obviously, the left sternal border often has a middle diastolic murmur.

(3) differentiation from ventricular septal defect: patients with ventricular septal defect have a very loud full systolic murmur accompanied by tremor, no systolic jet sound, X-ray film shows left atrial left ventricular large, pulmonary blood increased, ECG shows double-chamber hypertrophy or only right ventricular hypertrophy; echocardiography can be identified.

(4) Identification of pulmonary atresia with complete septal septum: attention should be paid to patients with neonatal or small infants, both of which may have cyanosis and heart failure and pulmonary blood loss, the most common type of pulmonary atresia, right ventricle Often dysplasia, and no obvious heart enlargement, ECG showed left ventricular hypertrophy, two-dimensional echocardiography can be initially identified, only selective film angiography can definitely identify atresia and severe stenosis.

(5) Identification with tricuspid valvular deformity: typical physical signs and ECG findings can be identified.

2. Identification of simple pulmonary stenosis and pulmonary artery stenosis combined with other malformations

(1) differentiation with pulmonary stenosis with small ventricular septal defect: this type of stenosis is more common in the funnel, because the ventricular septal defect is smaller, the right ventricular pressure can be higher than the left ventricular pressure, the exact identification depends on cardiovascular angiography .

(2) differentiation with pulmonary artery stenosis and patent ductus arteriosus: the clinical manifestations of these patients are patent ductus arteriosus, but there is a loud systolic murmur with a tremor and a jet sound above the left sternal border. Electrocardiogram of ventricular hypertrophy suggests pulmonary valve stenosis, which can be identified by echocardiography.

(3) Identification with Noonan syndrome: 50% of patients with this disease can be associated with congenital heart disease, and the most common malformation is pulmonary stenosis, often pulmonary dysplasia, in addition, can still be combined with atrial septal defect and left Cardiomyopathy, this patient has a special face, short stature, wing neck, drooping eyelids, etc., and hypogonadism can be identified.

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