Pulmonary artery stenosis

Introduction to pulmonary stenosis Pulmonary stenosis refers to the narrowing of the right ventricular funnel, the pulmonary valve or the total trunk of the pulmonary artery and its branches. It can exist alone or as part of other cardiac and visceral malformations such as tetralogy of Fallot, etc. About 10% of congenital heart disease, pulmonary stenosis is the most common pulmonary stenosis, accounting for about 90%, followed by funnel stenosis, vascular stenosis and its branch stenosis is rare. basic knowledge The proportion of illness: 0.08% of the specific population Susceptible people: no special people Mode of infection: non-infectious complication:

Cause of pulmonary stenosis

This disease is a common type of congenital heart disease caused by abnormal development of the embryonic stage, but there may also be secondary pulmonary stenosis, which is caused by other diseases, such as intrauterine infection. The disease, the pathophysiological changes of the disease are as follows:

First, the cause

Various types of pulmonary stenosis have different embryonic developmental disorders. At the 6th week of embryonic development, the arterial trunk begins to separate into the aorta and pulmonary artery. The original nodules of the three valves begin to form in the endometrium of the pulmonary artery and grow into the lumen. Then, the absorption and thinning form three pulmonary valves, such as the valve is in the process of growth, the three valve leaf junctions merge into a dome-shaped mouth of the mouth, that is, the formation of pulmonary stenosis, while the pulmonary valve develops, the heart The conical portion of the ball is absorbed into the right ventricular outflow tract (ie, the funnel). For example, the developmental disorder forms the outflow tract, the annular muscle hypertrophy or the hypertrophic muscle bundle crosses the wall and the compartment to form the right ventricular outflow tract funnel-type stenosis. During development, the sixth pair of arterial arches develop into left and right pulmonary arteries. The distal end is connected to the pulmonary arterioles, and the proximal end is connected to the pulmonary artery trunk. If the developmental disorder is formed, the venous artery branch or the pulmonary trunk stenosis is formed.

Second, pathological changes

Pulmonary stenosis: the three valve leaflet junctions merge into a dome-shaped thickened diaphragm, protruding into the cavity, the petal hole is fish-shaped, can be located at the center or on one side, the small petal hole is only 2 ~ 3mm, the general valve The hole is about 5~12mm, and there is a slightly ridged ridge in the junction of the leaf and leaf junction. In most cases, the three leaflets are fused to each other, and a few are double-leaflet fusion. The flap is often thickened and has a small shape. Nodules can form calcified plaques. Pulmonary valve rings generally have different degrees of stenosis. The right ventricle is hypertrophied due to blood flow obstruction, which can produce secondary right ventricular outflow tract fat hypertrophic stenosis and right ventricular enlargement. The cusp is incomplete.

The total trunk of the venous artery can show a stenosis and a fusiform enlargement, which often extends to the left pulmonary artery, and the total trunk of the pulmonary artery is significantly larger than the aorta.

There are two types of stenosis in the funnel: the first type is a diaphragm type stenosis, below the conical part, the right ventricular outflow tract forms a fibromuscular septum between the rupture of the egg wall, separating the right ventricle into two different sizes. In the heart chamber, the upper part of the upper wall is slightly enlarged, called the third ventricle, and the lower part is the right ventricle of the muscle hypertrophy. The center of the septum has a narrow channel with a size of about 3 to 15 mm. Stenosis often coexists with arterial stenosis, called mixed stenosis, and the second type is ductal stenosis, which is mainly characterized by diffuse muscle hypertrophy of the right ventricular outflow tract wall layer, forming a long narrow ventricular channel, this type of stenosis Often accompanied by pulmonary valve annulus and pulmonary trunk dysplasia, so no enlargement after pulmonary stenosis.

Third, physiological changes

Regardless of the type of pulmonary stenosis, the right ventricle is blocked, the right ventricular pressure is increased, and the increase is proportional to the degree of pulmonary stenosis. The intrapulmonary pressure remains normal or slightly decreased, so the right ventricle is There is a transvalvular pressure gradient in the pulmonary artery, and the pressure gradient increases with the degree of pulmonary stenosis. If the transvalvular pressure step is below 5.3 kPa (40 mmHg), it is a mild pulmonary stenosis, which affects right heart bleeding. Not large, when the cross-valve pressure step is between 5.34 ~ 13.33kPa (40 ~ 100mmHg) is moderate pulmonary stenosis, right ventricular bleeding begins to be affected, especially when the right heart discharge is reduced during exercise, when the cross-valve When the pressure difference is greater than 13.33 kPa (100 mmHg), the right ventricular discharge is obviously blocked. Even at rest, the right ventricle discharge is also reduced, and the right ventricular load is significantly increased. Over time, it will promote right ventricular hypertrophy. Right ventricular myocardial strain, right ventricular enlargement leads to tricuspid annulus enlargement, resulting in tricuspid valve insufficiency, followed by increased right atrial pressure, right atrial hypertrophy, when right atrial pressure is higher than left atrial pressure In the case of atrial septal fossa ovalis, it can cause blood to flow from the right atrium into the left atrium, clinically appear central purpura, long-term right ventricular load increases, eventually leading to right heart failure, jugular vein engorgement , hepatomegaly, ascites and lower extremity edema.

Pulmonary artery stenosis prevention

The incidence rate is about 10% of congenital heart disease, pulmonary stenosis is the most common pulmonary stenosis, accounting for about 90%, followed by funnel stenosis, vascular stenosis and its branch stenosis are rare, various types of pulmonary artery The stenosis of the mouth is different for embryonic developmental disorders. At the 6th week of embryonic development, the arterial trunk begins to separate into the aorta and pulmonary artery. The original nodules of the three valves begin to form in the endometrium of the pulmonary artery, and grow into the cavity, which is then absorbed. Thinning forms three pulmonary valves, such as the valve is in the process of growth, the three valve leaf junctions merge into a dome-shaped mouth of the mouth, that is, the formation of pulmonary stenosis, while the development of the pulmonary valve, the cone of the heart The part is absorbed into the right ventricular outflow tract (ie, the funnel part), such as the developmental disorder forming the outflow tract ring muscle hypertrophy or the hypertrophic muscle bundle across the wall and the compartment to form the right ventricular outflow tract funnel-type stenosis, and during embryonic development The 6th pair of arterial arches develop into left and right pulmonary arteries, the distal end of which is connected with the pulmonary arterioles, and the proximal end is connected with the pulmonary artery trunk. Pulmonary trunk or branch vein stenosis.

Pulmonary stenosis complications Complication

Generally, patients with severe stenosis may die of right heart failure. There are still some risks of postoperative complications in this disease. In addition to the complications that may be caused by open heart surgery in extracorporeal circulation, there are two main points: After the pulmonary stenosis is relieved, the blood volume of the pulmonary circulation is significantly increased. Therefore, the blood volume should be appropriately supplemented according to the arterial pressure and the central venous pressure to avoid postoperative hypocardiac excretion. If necessary, intravenous infusion of dopamine and cedilan. Cardiac pressurization drugs to enhance myocardial contractility, transition to hemodynamic stability, and second, such as outflow stenosis is not completely relieved, right ventricular pressure is still high, postoperative easy to cause right ventricular incision bleeding, and easy to produce right heart Depletion.

Symptoms of pulmonary stenosis Common symptoms Systolic murmurs, dizziness, tiredness, palpitations, cyanosis, cardiac dysfunction, obstruction, jugular venous anger, shortness of breath

First, clinical manifestations

The ratio of male to female is about 3:2, and the age of onset is mostly between 10 and 20 years old. The symptoms are closely related to pulmonary stenosis. Patients with mild pulmonary stenosis are generally asymptomatic, but gradually appear with age. It is characterized by poor labor endurance, nausea and shortness of breath after fatigue and fatigue. Severe stenosis may have dizziness or fainting episodes. In advanced cases, symptoms of right ventricular dysfunction, hepatomegaly and lower extremity edema may occur, such as coexisting room septum. Defects or patent fossa are not closed, showing cyanosis and clubbing (toe) at the mouth or toe.

Second, physical signs

Most of the patients are well-developed. The main sign is that the third to fourth ribs on the left sternal border can hear the III-IV loud and rough jet-like systolic murmur, which is transmitted to the left neck or the left subclavian region. The most loud noise can be heard. Exposure to systolic tremor, the intensity of the murmur varies with the degree of stenosis, blood flow velocity, blood flow and chest wall thickness, the second heart sound in the pulmonary valve area is often weakened, the patient with stenosis of the funnel is narrow, and the murmur and tremor are generally in the left third or At the fourth intercostal space, the intensity is lighter, and the second heart sound of the pulmonary valve area may not be alleviated, and sometimes even split.

In patients with severe pulmonary stenosis, the right ventricular hypertrophy can be seen to bulge forward in the left sternal border. In the anterior region of the anterior region, the pulsation of interest can be seen and the tricuspid valve is closed due to the relative closure of the tricuspid valve. A systolic murmur, when a right-to-left shunt occurs in the blood flow in the atrium, a purpura-like finger (toe) may appear on the patient's lips and the toes of the extremities.

Examination of pulmonary stenosis

X-ray inspection:

Mild pulmonary stenosis may have no abnormalities in the chest X-ray. Patients with moderate or severe stenosis showed mild or moderate enlargement of the heart, with right ventricular and right atrial hypertrophy, and the apex was raised upward due to right ventricular hypertrophy. In the case of pulmonary stenosis, the enlarged pulmonary artery segment protrudes outwardly, while the patient with stenosis of the funnel is flat or even depressed. The shadow of the hilar is reduced, and the blood vessels in the lung are small, especially in the outer third of the lung field. Therefore, the lung field is clear.

Pulmonary stenosis X-ray showed a mild to moderate enlargement of the heart, a blunt apex of the apex, a pulmonary artery segment, and a clear lung field.

ECG check:

The electrocardiogram changes the degree of stenosis, and the electrocardiogram of patients with mild pulmonary stenosis is in the normal range. Above the moderate stenosis, the right axis of the stenosis, the right ventricular hypertrophy, the strain and the inverted T are changed. The severe stenosis may have a high atrial hypertrophy. In the case of sharp P waves, some cases showed incomplete right bundle branch block.

Echocardiography:

Echocardiography in patients with pulmonary stenosis can indicate that the opening of the leaflets is limited, the leaflets are narrowly shaped with a dome-shaped protuberance, and the right ventricular outflow tract muscle hypertrophy and the extent of right ventricular and right atrial enlargement can be ascertained.

According to clinical signs, X-ray and echocardiography, general pulmonary stenosis is not difficult to make a preliminary diagnosis, but in some cases, in order to further confirm the diagnosis or differential diagnosis, to understand the degree of stenosis and accompanying cardiac malformation, help For correct surgical options, right heart catheterization or right ventricular angiography is necessary.

Right heart catheterization and selective right ventricular angiography:

Normal right ventricular systolic pressure is 2.0-4.0 kPa (15-30 mmHg), diastolic blood pressure is 0-0.7 kPa (0-5 mmHg), pulmonary systolic pressure is consistent with right ventricular systolic pressure, such as right ventricular systolic pressure higher than 4.0 kPa (30 mmHg) ), and the difference between the right ventricular and pulmonary systolic pressure step exceeds 1.3 kPa (10 mmHg), suggesting that there can be pulmonary stenosis, the magnitude of the transvalvular pressure step can reflect the degree of pulmonary stenosis, such as the transvalvular pressure step at 5.3 kPa (40mmHg) is mild stenosis, pulmonary valve orifice is about 1.5 ~ 2.0cm; if the pressure gradient is 5.3 ~ 13.3kPa (40 ~ 100mmHg) is moderate stenosis, the valve hole is about 1.0 ~ 1.5cm; The difference is 13.3 kPa (100 mmHg) or more for severe stenosis. The estimated valve hole is 0.5-1.0 cm. The right heart catheter is pulled out from the pulmonary artery to the right ventricle. The pressure is continuously recorded. According to the pressure curve pattern and the presence or absence of the third The type curve can be used to determine the pulmonary stenosis as a simple pulmonary stenosis or a funnel stenosis or a mixed stenosis.

1 valve type.

2 funnel type.

3 mixed type: continuous pressure measurement curve between pulmonary artery and right ventricle showed the location of pulmonary stenosis, 1mmHg=0.133kPa.

Selective right ventriculography does not have to be routinely examined, but for some difficult cases, the need for definite diagnosis and differential diagnosis, to understand the location and extent of stenosis, right ventricular angiography combined with right ventricular angiography, contrast agent injection into the right ventricle, In the pulmonary valve site, the contrast agent is blocked, and the valve fusion is dome-shaped into the pulmonary artery. The contrast agent is fan-shaped after being injected into the pulmonary artery through a narrow valve. The narrow funnel can present a narrow angiography in the right ventricular outflow tract. Agent image.

Diagnosis and differentiation of pulmonary stenosis

diagnosis

Ask family history to understand the genetic situation, investigate the impact of environmental factors, to explore the cause of congenital heart disease. 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 early pregnancy was estimated by environmental factors. The address of the mother and the mother at the time of production was investigated. About 24.8% of the mothers moved between starting pregnancy and production, so observing the production address may reduce congenital malformation and mother contact environment. The correlation is positive. The result should be investigated in the environment of the address at the time of pregnancy, and the prenatal examination is recommended.

Patients with mild pulmonary stenosis are clinically asymptomatic, can grow normally and adapt to normal living ability without surgery. Patients with moderate pulmonary stenosis usually have palpitations and shortness of breath after activity in the age of 20, if no surgical treatment is taken, The increase of age will inevitably lead to the right ventricular overload and the symptoms of right heart failure, thus losing the ability to live and work. Patients with very severe pulmonary stenosis often have obvious symptoms in early childhood. If they are not treated in time, they can often die in early childhood.

Differential diagnosis

(A) atrial septal defect: signs of mild pulmonary stenosis, ECG performance and atrial septal defect are quite similar.

(B) ventricular septal defect: the sign of the stenosis of the funnel is very similar to the ventricular septal defect, should pay attention to the identification (see the third section of this chapter "ventricular septal defect").

(C) congenital primary pulmonary artery dilatation: the clinical manifestations and ECG changes of this disease are similar to the light pulmonary stenosis, the differential diagnosis is difficult, right heart catheterization failed to find the right ventricular and pulmonary systolic pressure gradient Poor or other abnormal pressure, and no shunt, and X-ray shows the total dry arc expansion of the pulmonary artery, which is conducive to the diagnosis of this disease.

(D) tetralogy of Fallot: severe pulmonary stenosis, accompanied by atrial septal defect, and patients with right-to-left shunt cyanosis (Faler triad), need to be differentiated from tetralogy of Fallot.

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