Pulmonary hypertension

Introduction to pulmonary hypertension Pulmonary hypertension is an extremely serious disease. 75% of patients are concentrated in the 20-40 age group, and 15% of patients are under 20 years old. Symptoms of pulmonary hypertension include shortness of breath, fatigue, syncope, chest pain, and edema of the legs and ankles. In addition, cardiac auscultation can be heard P2 hyperthyroidism. If left untreated, the patient's pulmonary hypertension will gradually increase, and even shorten the life. Most of the symptoms associated with pulmonary hypertension are due to right heart failure. basic knowledge The proportion of illness: 0.0025% Susceptible people: no special people Mode of infection: non-infectious Complications: emphysema Chronic pulmonary heart disease

Cause of pulmonary hypertension

Increased pulmonary blood flow (35%):

(1) Congenital cardiovascular abnormalities of left-to-right shunt: atrial septal defect, ventricular septal defect, patent ductus arteriosus, permanent arterial trunk.

(2) acquired intracardiac shunt: aortic aneurysm rupture or aortic Valsalva aneurysm broke into the right ventricle or right atrium, ventricular septal perforation (defect) after myocardial infarction.

Increased vascular resistance around the lungs (20%):

(1) Pulmonary vascular bed reduction: pulmonary embolism caused by various causes.

(2) pulmonary artery wall lesions: 1 pulmonary arteritis: Raynaud's syndrome, scleroderma, localized intradermal calcium deposition, Raynaud's phenomenon, finger (toe) scleroderma and telangiectasis syndrome (CREST syndrome), class Rheumatoid arthritis, systemic lupus erythematosus, polyneuritis, dermatomyositis, granulomatous arteritis, eosinophilia, arteritis. 2 primary pulmonary hypertension: plexus pulmonary vascular disease, microthrombus formation, pulmonary vein occlusion disease. 3 pulmonary artery congenital stenosis.

(3) pulmonary fibrosis or interstitial granuloma: diffuse pulmonary interstitial fibrosis, radiation pulmonary fibrosis, miliary tuberculosis, pneumoconiosis, lung cancer, cystic fibrosis, idiopathic hemosiderosis, etc. .

(4) hypoxemia-induced pulmonary vasospasm: 1 chronic obstructive pulmonary disease: chronic bronchitis, emphysema, bronchial asthma. 2 respiratory dyskinesia: pleural disease, thoracic deformity, multiple polio, muscle atrophy, obesity. 3 plateau lack of oxygen. (5) Changes in blood viscosity: increased plasma viscosity, polycythemia, increased red blood cell accumulation, and increased red blood cell hardness.

Increased pulmonary venous pressure (25%):

(1) pulmonary vein occlusion: mediastinal tumor or granulomatosis, mediastinal disorder, congenital pulmonary vein stenosis.

(2) Heart disease: left ventricular dysfunction, mitral stenosis or insufficiency, mitral annular calcification, left atrial myxoma, three-room heart.

Pathogenesis

1. Pathogenesis :

The pulmonary circulation includes the right ventricle, pulmonary artery, capillaries and pulmonary veins. Its main function is to exchange gas. Hemodynamics has the following four characteristics: 1 low pressure: normal resting pulmonary artery pressure is 19/16mmHg, average pressure is (12 ±2)mmHg, systolic blood pressure does not exceed 25mmHg, 1/6 of the aorta, pulmonary vascular perfusion pressure is also low, the pulmonary artery and left atrial pressure difference is only 6mmHg, which is l/71/10 of normal aortic pressure. 2 small resistance: due to short pulmonary vessels, thin wall, large expansion, so blood flow resistance is small, normal human pulmonary vascular resistance is 1 / 5 ~ l/10 of systemic resistance. 3 fast flow rate: the lungs receive all the blood from the heart, but the process is much shorter than the systemic circulation, so the flow rate is fast. 4 large capacity: large area of pulmonary vascular bed, can accommodate 900mL of blood, accounting for 9% of the total blood.

Pulmonary artery pressure = pulmonary vascular resistance × pulmonary blood flow + left atrial pressure

Therefore, the pulmonary artery pressure is determined by pulmonary vascular resistance, pulmonary blood flow and left atrial pressure. The pulmonary artery roughly includes three kinds of caliber and structural blood vessels, that is, elastic arteries with an outer diameter of >1000 m, and muscle arteries with a diameter of 100 to 1,000 m. And small arteries with outer diameter <100pm, muscle arteries and small arteries are important parts of pulmonary artery pressure. The formation mechanism of pulmonary arterial pressure is very complicated and can be divided into the following cases:

(1) High-dynamic pulmonary hypertension (increased pulmonary blood flow): Due to the low resistance, low pressure and high volume of the pulmonary circulation, the pulmonary blood vessels can adapt to the increase of pulmonary blood volume without causing significant fluctuations in pulmonary arterial pressure, but there are certain limits. When the blood output is increased by 2 to 3 times, the average pulmonary artery pressure is only increased by 20% to 50%. When the blood pressure is increased by 4 to 5 times, the pulmonary artery pressure can be increased by 1 time. If the long-term continuous blood flow increases, the blood vessels will expand, and for a long time, Can cause changes in the structure of the pulmonary artery and become irreversible, pulmonary hypertension caused by increased pulmonary blood flow, more common in left-to-right shunt congenital heart disease or systemic circulation of large arteriovenous fistula (Eisenmenger syndrome), most of the pulmonary circulation at rest Normally, cardiac output increases significantly during exercise, such as a decrease in vasospasm or vascular bed, and a limited increase in vascular volume compensatory expansion.

(2) High-resistance pulmonary hypertension (increased vascular resistance around the lungs):

1 pulmonary vascular bed reduction: pulmonary vascular reserve capacity, large expansion, when the vascular bed is reduced by more than 70%, significant pulmonary hypertension will occur.

A. Extravascular compression: various diffuse pulmonary interstitial lesions such as pulmonary fibrosis, pulmonary granuloma and pulmonary infiltration, caused by bronchial tension changes, increased alveolar pressure, scar tissue contraction, lung tissue swelling or Tumor compression, etc., narrow and occlude small blood vessels in the lungs.

B. Causes of blood vessels itself: severe emphysema, alveolar septum rupture, many alveoli fuse into large bubbles, the capillaries are stretched and slender, or by the vascular wall itself inflammation or invasive lesions, small arterial intimal hyperplasia and middle layer hypertrophy.

C. Endovascular embolization: occlusion of pulmonary arterioles after arteritis, as well as pulmonary artery trunk and small vessel embolization or thrombosis.

2 pulmonary vasoconstriction: pulmonary vasoconstriction is the most important cause of increased pulmonary hypertension. Hypoxemia is a strong stimulating factor that causes pulmonary capillary contraction, which causes an increase in vascular resistance, leading to pulmonary hypertension, through chronic obstructive pulmonary disease ( COPD) Patients observed that pulmonary hypertension was closely related to pulmonary oxygen saturation (SaO2). When SaO2<80%, 2/3 patients had elevated pulmonary artery pressure, and SaO2<75% had 95.4% increased pulmonary artery pressure. High altitude pulmonary hypertension is also caused by hypoxia. The oxygen content in the air is related to the altitude. At an altitude of 3400m, the partial pressure of oxygen in the air is 100mmHg, and the altitude is 5000m. The partial pressure of oxygen in the air is 80mmHg. Acute pulmonary edema can occur due to acute hypoxia. For a long time, irreversible pulmonary hypertension is caused. Hypoxia-induced pulmonary vasoconstriction may be related to the following factors:

A. Autonomic nervous mechanism: pulmonary vasculature is governed by adrenergic sympathetic and cholinergic parasympathetic nerves. Adrenergic alpha and beta receptors are present around the pulmonary arterioles. When the oxygen partial pressure in the blood decreases, the partial pressure of carbon dioxide rises. When the ion concentration is increased, by stimulating the aorta body, the carotid sinus will impulse into the sympathetic center of the hypothalamus, and the reflex will cause the pulmonary artery to contract. In the case of acidosis, the vascular response to hypoxia contraction is significantly increased.

B. Humoral factors: In the absence of oxygen, the proliferation of mast cells in the lungs increases, the ability to produce histamine is enhanced, degranulation occurs, and histamine and serotonin are released, which directly affects the cell membrane, causing the loss of intracellular potassium ions. Increased calcium ions lead to increased muscle excitability. Prostaglandins increase in the lungs during hypoxia. Prostaglandin F2a (PGF2a) and thromboxane (TXA2) are potent pulmonary vasoconstrictors, which can directly affect calcium ion pairs. The stimulation and contraction of smooth muscle can cause platelet aggregation, promote thrombosis, increase vascular resistance, increase the activity of angiotensin I converting enzyme in the lung during hypoxia, increase angiotensin II, cause pulmonary vasoconstriction, and increase systemic pressure. It is also an important cause of increased pulmonary artery pressure.

C. Cellular factors: ATP production is reduced in hypoxia, cell membrane ATPase activity is decreased, potassium-sodium sulphate is lost in pulmonary artery smooth muscle, negative membrane potential is decreased, muscle excitability is increased, and free calcium in blood is also poisoned during hypoxia acidosis. The increase of ions promotes the entry of calcium ions into smooth muscle cells and initiates a contraction device, which can cause blood vessels to contract, increase resistance, and lead to pulmonary hypertension.

3 pulmonary vascular elasticity reduction: long-term hypoxia causes persistent pulmonary contraction or bronchial inflammation to affect the pulmonary arterioles, which can cause organic vascular damage, especially small arteries with an inner diameter of 300 m or less, causing smooth muscle edema, degeneration, necrosis, and elasticity. Plate rupture and endothelial cell and elastic tissue hyperplasia, fibrosis, and even luminal occlusion, thickening of the vessel wall, stiffness, and the formation of the mesenteric muscle layer in the pulmonary arterioles less than 80 m in diameter can reduce the compliance of the wall and increase Vascular resistance.

4 increased blood viscosity: can be seen in primary polycythemia or long-term hypoxia caused by secondary polycythemia to increase blood viscosity, when the hematocrit >50% can increase pulmonary vascular resistance.

(3) pulmonary venous hypertension (post-capillary pulmonary hypertension): due to the characteristics of pulmonary circulation, the pressure difference between pulmonary arteries and veins is very small, only 2 ~ 10mmHg, so some diseases cause pulmonary hypertension to increase when pulmonary venous pressure is increased. Common in mitral valve disease, three-atrial heart, left atrial myxoma, can also occur in long-term left ventricular dysfunction, left ventricular responsiveness, etc., pulmonary arteriolar responsive contraction or occurs in the lung when pulmonary venous pressure is elevated The interstitial fibrosis at the base causes the pulmonary vascular bed to be squeezed, which is also the cause of pulmonary hypertension. A slight increase in left atrial pressure has little effect on pulmonary artery pressure. If it is doubled, it will affect pulmonary artery pressure.

2. Pathological changes :

Pulmonary hypertension caused by any cause can cause anatomical and structural changes of pulmonary arterioles and muscular small arteries, thickening of the wall and stenosis of the lumen, late local atrophy and lumen expansion, as long as there is sufficient severity and time. In terms of pathological morphology, there are four main categories:

(1) plexus pulmonary artery disease: this type is most common in left-to-right shunt congenital heart disease, also seen in pulmonary artery blood from the aortic branch of pulmonary isolation and typical primary pulmonary hypertension, occasionally in the liver Hardened portal hypertension, portal vein thrombosis and schistosomiasis, AIDS, etc., histological features are muscular hypertrophy of the pulmonary artery, intimal hyperplasia, formation of concentric lamellar arrangement of intimal fibrosis, luminal obstruction, arterialization, vasodilatation Lesions, cellulose-like necrosis and plexus-like lesions are formed. The blood vessels are locally dilated. The wall is composed of a thin elastic membrane to form a dilated blood vessel. It is prone to thrombosis. The thrombotic endothelial cells enter the thrombus to form a sponge. Hemangioma.

(2) embolic and thrombotic pulmonary vascular disease: the muscle layer of the pulmonary artery is often not obvious, there are new and old thrombosis, thrombosis after the formation of eccentric plaque-like intimal fibrosis, and then the formation of fiber spacing.

(3) pulmonary venous hypertension pulmonary vascular disease: any disease that can block venous blood flow can cause similar pulmonary vascular disease, such as mitral valve disease, left atrial myxoma, left heart failure and mediastinal fibrosis, etc. Involved pulmonary arteries, muscle arteries, arterioles, lymphatic vessels, lung tissue are also involved, muscle type pulmonary artery middle layer hypertrophy, fine arterialization, severe intimal fibrosis, pulmonary vein thickening arterialization and intimal fibrosis.

(4) Hypoxic pulmonary hypertension pulmonary vascular disease: pulmonary vascular disease is mainly limited to smaller blood vessels, the arterioles are mechanized, the intima has longitudinal smooth muscle cell bundles or layers, similar lesions can also be seen in venules, larger muscles. The type of pulmonary artery may be normal or slightly moderately thick.

Pulmonary hypertension prevention

Secondary pulmonary hypertension is related to congenital heart disease. The current cause of primary pulmonary hypertension is still unclear. The occurrence of congenital heart disease is a comprehensive result of various factors. To prevent the occurrence of congenital heart disease, publicity and education of popular science knowledge should be carried out. Focus on monitoring the age-appropriate population and give full play to the role of medical staff and pregnant women and their families.

1. Get rid of bad habits, including pregnant women and their spouses, such as smoking, alcohol and so on.

2, active treatment of diseases affecting fetal development before pregnancy, such as diabetes, lupus erythematosus, anemia and so on.

Pulmonary hypertension complications Complications emphysema chronic pulmonary heart disease

Chronic obstructive emphysema, chronic pulmonary heart disease, right heart failure and other complications may occur.

Pulmonary hypertension symptoms Common symptoms Labor dyspnea chest pain fatigue angina angina hemoptysis hoarseness fatigue liver enlargement arrhythmia

1, symptoms :

Including the symptoms of the primary disease and the symptoms caused by pulmonary hypertension, the symptoms of pulmonary hypertension itself are non-specific, mild pulmonary hypertension can be asymptomatic, with the development of the disease can have the following performance:

(1) Labor dyspnea: due to decreased pulmonary vascular compliance, cardiac output cannot increase with exercise, and dyspnea after physical activity is often the earliest symptom of pulmonary hypertension.

(2) fatigue: the result of hypoxia due to decreased cardiac output.

(3) syncope: caused by a sudden decrease in blood supply to the brain tissue, usually after exercise or sudden rise, but also due to occlusion of the pulmonary artery by a large embolism, sudden arrhythmia or arrhythmia.

(4) angina pectoris or chest pain: due to reduced right coronary artery perfusion, myocardial relative blood supply, chest pain may also be due to pulmonary artery trunk or main branch hemangioma-like expansion.

(5) hemoptysis: pulmonary hypertension can cause microvascular aneurysm rupture and hemoptysis at the beginning of pulmonary capillaries.

(6) hoarseness: pulmonary artery expansion caused by recurrent laryngeal nerve.

2, signs :

When the pulmonary artery pressure is significantly increased, the right atrium is enlarged, and the following signs may appear in right heart failure: obvious a-wave of the jugular vein, enhanced pulsation of the pulmonary valve area, right ventricular lift pulsation, systolic murmur of the pulmonary valve area, tricuspid valve Regional systolic reflux murmur, right ventricular third, 4 heart sounds, right heart failure can occur after jugular vein engorgement, liver enlargement, positive hepatic jugular venous return, lower extremity edema, severe pulmonary hypertension, decreased cardiac output The pulse is weak and the blood pressure is low.

The early clinical symptoms of pulmonary hypertension are atypical, often misdiagnosed or missed. For early diagnosis, it is necessary to closely combine clinical manifestations, signs and laboratory tests. According to different conditions, non-invasive or traumatic examination methods are used. First, there is no pulmonary hypertension. Then determine its severity and finally determine whether it is primary or secondary.

1. Be alert to early symptoms

Fatigue, exertional dyspnea and syncope cannot be considered as non-specific manifestations of chronic disease, which may be the earliest manifestation of patients with pulmonary hypertension.

2, special signs can indicate the cause

Such as sitting breathing, paroxysmal nocturnal dyspnea, lung squeaky sound and pleural effusion, suggesting that pulmonary hypertension is caused by post-capillary lesions, heart murmur can be judged by rheumatic valvular disease or congenital heart disease; Arterial murmur may be aortitis, pulmonary vascular murmur suggests pulmonary stenosis through which blood flows, and there may be thrombosis or pulmonary arteriovenous fistula at this site.

3, full use of non-invasive examination

Electrocardiogram with left atrium or left ventricular hypertrophy suggests that pulmonary hypertension may be cardiogenic, X-ray chest radiograph shows large pulmonary venous flow redistribution or Kerley's B line reflects pulmonary venous hypertension, pulmonary hypertension mainly occurs in left-to-right shunt heart Echocardiography can accurately diagnose pulmonary hypertension caused by certain heart disease. Pulmonary function test can help identify obstructive or restrictive lung disease. Blood gas analysis can distinguish whether there is hypoxic pulmonary hypertension. Radionuclide can show lung segment. And above thromboembolic pulmonary hypertension.

4, right heart catheterization is the most reliable means of examination, can determine the severity of pulmonary hypertension, with or without reversibility, and contribute to the diagnosis of the cause, such as elevated pulmonary capillary wedge pressure, indicating post-capillary pulmonary hypertension, measured differently The blood oxygen content of the site can be found to be left to right, and thrombus, vascular malformation, hypoplasia or stenosis can also be detected by selective pulmonary angiography.

5, lung tissue biopsy

Pulmonary hypertension with the cause may not be clarified by the above exclusion diagnosis method, which may be chronic recurrent pulmonary thromboembolism, pulmonary vein occlusion disease and primary pulmonary hypertension, and lung biopsy can be identified.

Pulmonary hypertension test

1, blood test :

Such as concurrent infection of peripheral blood leukocytes and neutrophils significantly increased, often hemoglobin decreased and other performance.

2, lung biopsy:

Intraoperative lung biopsy in patients with congenital heart disease can help to judge its prognosis. Patients with severe pulmonary hypertension not only increase the complications and mortality of surgical treatment, but also are the main factors determining the long-term efficacy of surgery.

3, ECG:

Increased pulmonary arterial pressure makes the right ventricle overload, long-term right ventricle, right atrial hypertrophy, ECG changes can reflect the degree of pulmonary hypertension, showing right ventricular and right atrial enlargement, including right axis of the electrocardiogram, pulmonary P wave, V1 ~ V3 large R wave, T wave inversion and ST segment reduction, when the ECG shows right ventricular hypertrophy, the average pulmonary artery pressure has exceeded 30mmHg, but different causes may be inconsistent, such as atrial septal defect when the pulmonary artery pressure reaches 25mmHg, it shows right ventricular hypertrophy, For ventricular septal defect, the patent ductus arteriosus usually exceeds 35mmHg, and the right pulmonary hypertension exceeds 40mmHg to show right ventricular hypertrophy.

4, X-ray inspection

(1) Cardiac changes: right atrium, right ventricle enlargement, "conical" expansion of the pulmonary artery segment, chest coning height 7 mm in right anterior oblique position, aortic junction shrinking.

(2) Right lower pulmonary artery dilatation: the normal right lower pulmonary artery trunk width is (12.1±1.2) mm, >15mm is abnormal, the degree of expansion is related to pulmonary hypertension, and the ratio of right lower pulmonary artery transverse diameter to tracheal transverse diameter is 1.07.

(3) Hilar shadow widening: The hilar and thoracic cage were (34±4)% normal, and the increase in value was associated with an increase in pulmonary arterial pressure (correlation coefficient 0.74).

(4) Increased ratio of heart to chest: normal cardiothoracic ratio <0.5, heart-thorax ratio >0.5 in pulmonary hypertension.

(5) Central pulmonary artery dilatation: the peripheral branches are small, and the two form a sharp contrast.

(6) Differences in X-ray changes of different causes:

1 pulmonary blood flow increased pulmonary artery pulmonary artery segment straightening or prominent: the vertical distance between the base of the pulmonary artery segment and the most prominent 3mm, the basal line of the pulmonary artery segment is extended by >60 ~ 70mm, the branch vasodilation is distorted, the pulmonary blood is increased, and the pulmonary vein is normal. .

2 Pulmonary capillary resistance increased X-ray characteristics: pulmonary artery segmentation, large pulmonary vein blood redistribution, lower pulmonary vein vascular thinning, upper lung field normal or thickening, right lower pulmonary artery transverse diameter widened, gap line appeared ( Kerley's B) and hemosiderin are shadows.

3 Capillary anterior resistance increased X-ray characteristics: the pulmonary artery segment was prominent, the hilar vasculature was enlarged, the peripheral blood vessels were slender or residual, and the pulmonary vein shadow was normal.

5, echocardiogram:

Echocardiography is more sensitive to pulmonary hypertension than X-ray. Its sensitivity is 52% and correctness is 85%. Therefore, right ventricular wall hypertrophy and right heart chamber can be found at an early stage. Cardiovascular enlargement, main indicators:

1 The pulmonary artery echo curve "a" wave disappeared, and its sensitivity was 82.35%.

2 The right ventricular diastolic diameter increased (>20mm).

The thickness of the 3-chamber compartment increased and moved in the same direction as the posterior wall of the left ventricle.

4 The initial opening slope of the mitral valve decreased.

5 Pulmonary valve echo curve systolic mid-term notch, its sensitivity was 94.12%.

6 Right ventricular ejection (RVPEP) prolonged, right ventricular ejection period (RVET) shortened, so the RVPEP/PVET ratio increased.

In recent years, the use of ultrasound Doppler to estimate pulmonary arterial pressure has gained a lot of gratifying experience as an important means of diagnosing pulmonary hypertension. The Doppler effect is used to show the direction and velocity of blood flow, providing time and spatial information of blood flow in the heart and large blood vessels. The use of echocardiographic parameters to assess pulmonary arterial pressure is currently the most ideal non-invasive method for the quantitative diagnosis of pulmonary hypertension:

1 Pulmonary artery blood flow acceleration time (AT) was associated with pulmonary systolic pressure (SPAP) and mean pulmonary artery pressure (MPAP) (r = 0.80).

2 Right ventricular outflow tract blood flow acceleration time (ACT) was associated with mean pulmonary arterial pressure (r = 0.63 to 0.88).

3 Tricuspid blood flow velocity (TR) and tricuspid pressure difference (TG) were associated with pulmonary systolic pressure (SPAP) (r=0.77-0.94) and pulmonary diastolic blood pressure (DPAP) (r=0.80).

Diagnosis and diagnosis of pulmonary hypertension

Attention should be paid to the identification of primary and secondary pulmonary hypertension:

1. Secondary pulmonary hypertension:

Has caused right heart hypertrophy, strain or right heart failure is easier to diagnose PH, but the patient's condition is often critical, has reached the late stage of the disease, treatment is difficult, the prognosis is not good, therefore, early diagnosis of pulmonary hypertension should be done to find pulmonary hypertension The cause.

Congenital heart disease and chronic lung disease are common causes of pulmonary hypertension. Heart murmur can help to determine congenital heart disease or rheumatic valvular disease, but the original heart murmur may be reduced or disappeared during pulmonary hypertension, and pulmonary hypertension is shown. For right ventricular systolic overload, if there is left atrial or left ventricular hypertrophy, the cause of pulmonary hypertension may be cardiogenic, X-ray examination is also characteristic, and it is helpful to find the cause of pulmonary hypertension, X-ray The diagnosis of lung parenchymal disease is obvious. Large pulmonary venous blood redistribution and Kerleys B line reflect pulmonary venous hypertension. Pulmonary blood increase is mainly seen in left-to-right shunt congenital heart disease, mitral stenosis, left atrial enlargement and Valvular calcification was found. Echocardiography can accurately determine the degree of pulmonary hypertension and changes in cardiac structure. Right heart catheterization can measure the degree of pulmonary hypertension, estimate whether it is reversible, and select pulmonary angiography (including DSA) to find thrombus. , vascular malformation, hypoplasia or stenosis, lung biopsy is also feasible for unexplained pulmonary hypertension to further Make a diagnosis.

2, primary pulmonary hypertension:

Any patient with unexplained exercise dyspnea, fainting during exercise, should be suspected of this disease, if P2 is reluctant, combined with X-ray, ECG, echocardiography and cardiac catheterization, after congenital heart disease can be ruled out Confirmed diagnosis.

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