Primary pulmonary hypertension

Introduction to primary pulmonary hypertension Primary pulmonary hypertension (primary pulmonary hypertension) is a rare disease that is distinguished from secondary pulmonary hypertension because its cause is unknown. basic knowledge Sickness ratio: 0.001%-0.005% Susceptible people: no special people Mode of infection: non-infectious Complications: pulmonary embolism, sudden death, syncope

Cause of primary pulmonary hypertension

(1) Causes of the disease

The basic pathological condition of primary pulmonary hypertension is plexus pulmonary artery disease. The cause of this disease is unknown. There is no single etiological factor that can explain the pathogenesis of the disease. It is probably the end result of long-term interaction of certain etiological factors, and the primary pulmonary artery. The possible causes of high pressure are described below.

1. Pulmonary thromboembolism: Initially, some authors believe that many small clinical subtypes of thromboembolism may be the cause of most primary pulmonary hypertension, because pathological findings, clinically diagnosed primary pulmonary hypertension patients are about half of chronic pulmonary thrombosis Embolism, but later studies found that histological thromboembolic pulmonary hypertension is different from plexus primary pulmonary hypertension, thromboembolic pulmonary hypertension, pulmonary vascular middle layer hypertrophy, intimal fibrosis eccentric, never dilatation Lesions, cellulose-like arteritis and plexiform lesions are formed, which are different from those of plexus pulmonary artery disease.

2. Vasoconstriction: The formation of plexiform lesions is the final vascular morphological change of primary pulmonary hypertension; and the early stage is the arterialization of the small arteriolar hypertrophy and the smooth muscle of the smooth muscle, suggesting that the vasoconstriction may be the primary pulmonary artery. The initial mechanism of high pressure, vasodilator drugs can reduce pulmonary artery pressure and pulmonary vascular resistance in some patients, further support the vasoconstriction mechanism involved in the occurrence of primary pulmonary hypertension, Raynaud's disease often combined with primary pulmonary hypertension, is also beneficial The etiology of vasoconstriction has now recognized the relationship between pulmonary vascular endothelium and adjacent smooth muscle. The relaxation of acetylcholine in rabbit arteries depends on the integrity of the endothelium. Endothelial cell damage can reduce endogenous pulmonary vasodilators (prostaglandins and The formation of nitric oxide and the release of certain growth factors promote smooth muscle hypertrophy, but the mechanism of vascular contraction caused by abnormal endothelial cell function is not fully understood. Recently, it has been found that primary pulmonary hypertension pulmonary arteriolar smooth muscle cells and secondary Pulmonary hypertension is depolarized, and the cytoplasm contains a higher concentration of calcium. The voltage potassium channel blocker 4-aminopyridine does not increase the intracellular calcium content of primary pulmonary hypertension, but it can increase the intracellular calcium level of secondary pulmonary hypertension, indicating that some primary pulmonary hypertension is absent in KV channel of pulmonary vascular smooth muscle cells. Or down-regulation, suggesting that potassium channel abnormalities may play a role in the etiology of primary pulmonary hypertension.

3. Autoimmune diseases: systemic lupus erythematosus, Raynaud's disease, CREST syndrome, scleroderma, rheumatoid arthritis, dermatomyositis, polymyositis and mixed connective tissue disease can be combined with primary Pulmonary hypertension, primary pulmonary hypertension, 29% to 40% of circulating antinuclear antibodies positive, 11% with Raynaud's phenomenon, 8 cases of CREST syndrome [calcium deposition, Raynaud's phenomenon, esophageal dysmotility, finger (toe) hard Pelvic disease and telangiectasia in 7 patients with pulmonary hypertension, suggesting that primary pulmonary hypertension is partly related to autoimmune diseases.

4. Family factors: In 1927, Clarke et al first reported that more than one member of a single family had unexplained pulmonary hypertension. In 1970, Wagenvoort collected 58 patients with primary pulmonary hypertension in 28 families, including a pair of twins, a family. It can also be inherited for several generations. It has been reported that a family has abnormal fibrinolysis, suggesting that pulmonary hypertension may be associated with recurrent microthrombotic dysfunction, but other families have not found this abnormality. In recent years, many primary The family of pulmonary hypertension has been investigated for its full genetic nature. It is believed that familial primary pulmonary hypertension is characterized by autosomal dominant disease, with incomplete penetrance and early genetic inheritance, further identifying that gene defects are located in a special Chromosomes, a genetic interpretation of familial pulmonary hypertension, involve a more extended mutation in trinucleotide replication.

5. Factors related to pregnancy and menstrual cycle: Primary pulmonary hypertension is often first discovered during pregnancy, and hemodynamic changes are aggravated during pregnancy; menstrual cycles can affect the reactivity of blood vessels, and it is unclear whether it also affects pulmonary vessels. As for the reason for the increase of primary pulmonary hypertension in women of childbearing age, it is still unclear. It is obviously not caused by a single cause. Some people have suggested that amniotic fluid embolism may be the cause of primary pulmonary hypertension, but histological examination failed to confirm the residual. Amniotic fluid embolism exists.

6. Drugs and diet: Most patients with primary pulmonary hypertension have no history of irregular medication and abnormal diet. After the application of the dietary drug aminorex in Europe from 1967 to 1970, the incidence of primary pulmonary hypertension suddenly increased 10-fold. After the "popular" soon subsided, about 2% of patients taking aminorex developed pulmonary hypertension, these people may be genetically susceptible or related to commonly used drugs, such as acetaminophen, which can alter liver metabolism, they are associated with primary Patients with pulmonary hypertension have different prognosis. Most of them recover after stopping the drug. The relationship between oral contraceptives and primary pulmonary hypertension is not clear. Some patients may be related to the disease.

7. Liver cirrhosis and portal hypertension: Pulmonary hypertension can occur in patients with cirrhosis, histological changes can not be distinguished from primary ones, and the second disease occurs as 0.016% to 0.26% of cirrhosis autopsy, cirrhosis and primary pulmonary artery High pressure occurs at the same time, which may be part of the autoimmune process. Although portal vein thrombosis is associated with pulmonary embolism, its lung histology is similar to primary pulmonary hypertension, rather than thromboembolic lesions.

8. Human immunodeficiency virus (HIV) infection: In 1987, Kim et al first reported a link between HIV infection and plexus pulmonary artery disease. Several reports have confirmed that the incidence of pulmonary hypertension in HIV-infected patients increases, its clinical, blood flow There is no significant difference between learning and prognosis and primary pulmonary hypertension. Pulmonary hypertension can occur at any stage of HIV infection. The time from diagnosis of HIV infection to pulmonary hypertension is less than 1 year to 9 years. Pathological changes are similar to plexus pulmonary artery disease. Pulmonary vein occlusion or pulmonary arteriolar and arterial thrombosis are rare, consistent with the pathological changes of familial primary pulmonary hypertension. The diagnosis should be based on seropositive HIV infection and pre-capillary pulmonary hypertension associated with HIV infection. To determine and exclude the presence of secondary pulmonary hypertension, the hypothesis that HIV infection directly or indirectly causes pulmonary vascular disease is: 1 direct infection of pulmonary vascular smooth muscle cells; 2 activation of angiogenic factors as a result of HIV infection; 3 HIV-infected T cells cause endothelial damage; 4 blood vessels caused by herpes simplex virus and/or cytomegalovirus infection Injury.

9. Other causes: 13 of the 13 patients with primary pulmonary hypertension have decreased platelet survival time, suggesting that platelets may be involved in the development of primary pulmonary hypertension. The factors released by platelets can stimulate smooth muscle hyperplasia in vitro. In rabbit lung vascular endothelial cell injury, smooth muscle hyperplasia, hyperplasia was significantly inhibited when thrombocytopenia, indicating that platelets play a part in the occurrence of pulmonary hypertension, thromboxane A2 is known to cause platelet aggregation and pulmonary vasoconstriction, pulmonary hypertension patients The thrombin B2, a degradation product in the blood, is significantly increased. It is unclear whether this increase is primary or secondary. The literature reports a decrease in pulmonary artery pressure after indomethacin (prostaglandin-like substance inhibitor). The involvement of platelets and prostaglandins, including leukotrienes, in the pathogenesis of primary pulmonary hypertension remains to be further studied.

(two) pathogenesis

For several decades, pulmonary vasoconstriction has been used as the initial mechanism of primary pulmonary hypertension, which plays a leading role in the pathogenesis, diagnosis and clinical management of the disease, ie, etiological factors smooth muscle cells vasoconstriction fixed pathological changes, This view is directly inferred from arterial hypertension because vasoconstriction plays a key role in arterial hypertension; the thickening of the pulmonary resistance vessels in patients with primary pulmonary hypertension supports the idea of vasoconstriction, however, Recently, although the pulmonary vascular tone is increased in patients with primary pulmonary hypertension, it is more like a participatory factor than an initial mechanism. The theory of endothelial dysfunction is increasingly dominant, ie, etiological factors endothelial cells dysfunction vasoconstriction fixed pathological changes, the general view is that pulmonary arterioles and arteriolar endothelial injury is the initial process of pulmonary hypertension, shunt pulmonary hypertension, dietary (wild lily alkaline) pulmonary hypertension, middle layer smooth muscle hyperplasia support this view, endothelium The direct effect of injury on vascular smooth muscle may cause a cascade reaction, ending Primary pulmonary hypertension.

Clinically diagnosed primary pulmonary hypertension, in addition to true primary pulmonary hypertension, may include recurrent pulmonary thromboembolism, pulmonary venous occlusion, pulmonary vascular endothelial disease and primary pulmonary arteritis, etc., but as a The physical entity of the disease, the true pathological changes of primary pulmonary hypertension should be characterized by plexus pulmonary artery disease, which mainly affects the pulmonary muscle arteries and arterioles, often involving the middle, intima or the entire arterial wall.

Middle layer lesions: the middle layer is the muscular layer, the smooth muscle tissue is abnormally increased, the muscle layer is thickened, and the smooth muscle cells can be extended to some muscle type or no muscle type intravesicular arterioles. The degree of middle layer hypertrophy varies depending on the patient and the blood vessel. For simple muscular layer hypertrophy, intimal hyperplasia may also be associated. With the progression of the lesion, the smooth muscle of the middle layer of hypertrophy may be partially or completely replaced by fibrous tissue, degenerated, atrophied, resulting in thinning of the middle layer and expansion of the vascular lumen.

Endometrial lesions: no matter which stage of the middle lesions can be combined with endometrial changes, there are two main types: 1 endometrial cell hyperplasia, occurs in the early stages of the disease, reversible; 2 centripetal lamellar (onion) Intimal fibrosis, composed of myofibroblasts and elastic fibers, is separated by a rich cell-free connective tissue matrix, and the centripetal lamellar intimal fibrosis reflects the progression of the lesion, which is mostly irreversible.

The entire arterial wall lesion: affecting the full thickness of the arterial wall lesions are arteritis, plexiform lesions and dilated lesions, arteritis is a primary inflammatory process, often involving the intima and the middle layer, less invasion of the adventitia, can occur Necrosis and cellulose exudation (cellulosic necrosis), polymorphonuclear leukocytes and lymphocytes infiltrate, arteritis can be scarred after healing, and there is calcium and iron fibrosis. The plexus-like lesion is the primary pulmonary artery. The characteristic marker of high pressure is characterized by aneurysm-like dilation near the opening of the larger open muscle artery and small artery. The tumor cavity is filled with a thin-walled vascular network, the inner layer is lined with endothelial cells, and the middle layer is partially or completely Destruction, the adventitia is replaced by granular tissue, the proximal end of the lesion, the open artery is narrowed, and the intima is fibrotic; the distal, plexus-like lesion enters the dilated thin-walled vascular network and the cellulose-like necrotic blood vessel, cellulose-like Necrotic vascular lumen contains platelets or thrombi, and it is unclear whether the dilated lesion is an independent change or a partial stage of the development of the plexus lesion.

It should be pointed out that plexus pulmonary artery disease is not the only pulmonary hypertension, but also can be seen in shunt congenital heart disease, connective tissue disease and other pulmonary hypertension. Some authors also describe the pathological changes of primary pulmonary hypertension. Eccentric intimal fibrosis, thrombosis recanalization and pulmonary vein disease, etc., but these changes are not caused by plexus pulmonary artery disease, but the pathological findings of recurrent pulmonary thromboembolism or pulmonary vein occlusion.

The etiology and pathogenesis of primary pulmonary hypertension remain unclear. The extensive pulmonary muscle arterial and arteriolar stenosis and obstruction significantly increase pulmonary circulation resistance, which can exceed 12 to 18 times normal, even up to 350 kPa·s/ L or more; pulmonary systolic blood pressure reached 17.33 kPa (130 mmHg), the average pressure reached 11.33 kPa (85 mmHg); pulmonary arteriolar pressure and left atrial pressure were normal, due to increased right ventricular afterload, right ventricular hypertrophy and dilatation, ventricular generation When the repayment function is low, the right ventricular end-diastolic pressure and right atrial pressure are significantly increased, and the cardiac output is gradually decreased. The severely ill patients are often lower than the normal 50%, the systemic blood pressure drops, and the systolic blood pressure often falls to 12.00 to 13.33 kPa ( 90 to 100 mmHg) or lower, the pulse pressure is narrowed, the tissue is poorly perfused, and peripheral hair is developed.

The normal right heart supply is different from the left heart. Not only in the diastolic phase, but also in the systolic coronary blood vessels, there is blood flow, that is, "dual-stage blood supply", but as the right ventricular pressure increases, the right heart supply gradually becomes diastolic. Myocardial blood supply is reduced; at the same time, due to right ventricular hypertrophy, increased oxygen consumption, myocardial ischemia, in addition to may cause angina, but also promote cardiac function deterioration, the formation of a vicious circle, and finally lead to right heart failure, in addition, due to hardening of the blood vessels, blood vessels Decreased bed, decreased lung compliance, decreased lung capacity, decreased capillary blood flow, imbalance of lung ventilation/perfusion ratio, pulmonary dysfunction, and decreased arterial blood flow, arteriovenous blood caused by poor tissue perfusion Hypoxemia and compensatory hyperventilation, hypoxemia and compensatory hyperventilation, decreased arterial carbon dioxide partial pressure and respiratory alkalosis resulted from increased oxygen partial pressure difference and increased right atrial pressure.

Primary pulmonary hypertension prevention

The etiology of primary pulmonary hypertension is unclear, epidemiological data is limited, and no similar animal models are available for study, so its prevention is difficult and can only be based on the presumed cause.

Primary pulmonary hypertension complications Complications, pulmonary embolism, sudden death

There may be complications such as right heart failure, pulmonary infection, pulmonary embolism, sudden death, and syncope.

Symptoms of primary pulmonary hypertension Common symptoms Fatigue dyspnea cyanosis arrhythmia hemoptysis bradycardia

1. Symptoms Primary pulmonary hypertension is divided into three stages according to pulmonary artery pressure and cardiac output: initial, late and terminal (Fig. 1), initial (stage I): pulmonary artery pressure gradually increases, cardiac output Normal blood volume, patients are usually asymptomatic, only feel uncomfortable during intense activities; late (stage II): pulmonary artery pressure is stable, heart discharge remains normal, all symptoms can appear, clinical condition is still stable; Stage III): pulmonary hypertension was less fixed, cardiac output decreased, symptoms worsened, cardiac decompensation, and 187 cases of primary pulmonary hypertension collected by the US multicenter were analyzed. The common initial symptoms are as follows: Difficulty breathing (60%), fatigue (73%), chest pain (47%), dizziness (41%), edema (37%), syncope (36%), palpitations (33%), we analyzed 41 cases that could not be explained In patients with pulmonary hypertension, the incidence of symptoms was 88% of dyspnea, 48% of chest pain, 35% of dizziness, 15% of syncope, 27.5% of hemoptysis, and 7.5% of Renault.

(1) Dyspnea: It is the most common symptom, characterized by labor, which is related to factors such as decreased cardiac output, imbalance of lung ventilation/blood flow ratio, and decreased ventilation per minute.

(2) Chest pain: It can be a typical angina pectoris, often occurs when labor or mood changes, due to increased right heart load, increased myocardial tissue thickening and oxygen consumption in the right ventricle, and decreased myocardial ischemia caused by decreased blood supply to the right coronary artery.

(3) syncope: including before syncope (vertigo) and syncope, more than after the activity, can also occur at rest, caused by a sudden decrease in oxygen supply to the brain tissue, the following conditions can be induced:

1 pulmonary vascular high resistance limits the increase of exercise heart output;

2 hypoxic venous blood is suddenly diverted to the systemic circulatory system;

3 body circulation resistance suddenly drops;

4 pulmonary arterioles suddenly paralyzed;

5 large emboli suddenly blocked the pulmonary artery;

6 sudden arrhythmia, especially bradycardia.

(4) Fatigue: tissue hypoxia caused by decreased blood output and reduced oxygen exchange and transport.

(5) hemoptysis: different from pulmonary venous hypertension hemoptysis, pulmonary hypertension, hemoptysis mostly from the rupture of pulmonary capillary anterior microangioma, hemoptysis is usually less, but also due to massive hemoptysis.

Symptoms in patients with primary pulmonary hypertension are non-specific and occur after progression of pulmonary hypertension. Therefore, it is speculated that there is a clinical incubation period before abnormal changes in pulmonary circulation, which is important for further examination of people with risk factors for pulmonary hypertension. For early diagnosis and early treatment.

2. Physical examination: The signs of primary pulmonary hypertension are related to elevated pulmonary arterial pressure and right ventricular dysfunction. Usually, pulmonary hypertension is above moderate, and physical examination has a positive finding. Common respiratory frequency increases, pulse rate, Small, early cyanosis is not obvious, due to decreased right ventricular hypertrophy compliance, increased jugular vein pulsation, jugular vein filling in right heart failure, lifting pulsation in the lower left sternal border, reflecting right ventricular enlargement, left intercostal space See or touch the systolic pulsation of the pulmonary artery, and can close the pulmonary valve to close the vibration. The area auscultates audible and systolic jet sounds and jet murmurs, the second sound of the pulmonary artery and the second heart sounds of different distances, pulmonary artery pressure The higher the pulmonary vascular compliance, the narrower the division. When the right heart fails, the division is fixed, the severe pulmonary hypertension, the pulmonary artery is obviously dilated, and the early diastolic reflux murmur of pulmonary valve insufficiency may occur. Also known as Graham Steel. The murmur, in the fourth intercostal space on the left sternal border, can be heard and the tricuspid systolic reflux murmur, enhanced during inhalation, usually from the right heart Expansion, also found in papillary muscles and tendons spontaneous rupture, the right disposition fourth, third heart sound which reflect right ventricular hypertrophy and right ventricular dysfunction.

Physical examination is helpful in determining pulmonary hypertension, but it is not completely different whether pulmonary hypertension is primary or secondary.

Examination of primary pulmonary hypertension

Peripheral red blood cells increased, patients with anemia and thrombocytopenia, blood gas analysis PH value was normal, PaCO2 decreased, PaO2 normal or decreased.

Pulmonary function and arterial blood gas analysis: pulmonary function is characterized by restrictive ventilatory dysfunction and diffuse dysfunction, no airway obstruction, early, arterial oxygen partial pressure can be normal, but most patients have mild to moderate hypoxemia, due to Caused by decreased cardiac output and imbalance of ventilation/blood flow, severe hypoxemia is associated with open foramen ovale, and almost all patients are accompanied by respiratory alkalosis.

1. Chest X-ray examination is helpful for the judgment of pulmonary hypertension, but no sign can accurately reflect the degree of pulmonary hypertension. X-ray signs commonly used to indicate pulmonary hypertension are:

1 The right lower pulmonary artery is widened, and the normal value of the Chinese is less than 15mm;

2 The ratio of the width of the hilum to the transverse diameter of the 1/2 chest is increased, that is, the ratio of the distance from the anterior midline to the edge of the pulmonary artery and the transverse diameter of the 1/2 thoracic, the normal value is (28.1±4.5)%;

3 The thoracic index of the hilum increased, that is, the ratio of the sum of the distance between the main midline of the right pulmonary artery and the main branch of the right pulmonary artery to the transverse diameter of the entire thorax, the normal value was (34±4)%;

4 pulmonary artery segment protruding, the normal value is less than 3 mm;

5 The expansion of the hilar arteries is in sharp contrast with the fineness of the peripheral texture or is residual;

6 right atrium, room enlargement;

7 The ratio of cardiothoracic is increased, normal is less than 0.5. It should be pointed out that the chest X-ray of mild to moderate primary pulmonary hypertension can be seen without abnormalities. The critically ill patients have obvious changes and the sensitivity of diagnosis is higher.

2. ECG can not directly reflect the increase of pulmonary artery pressure, can only suggest the right atrium, room enlargement or hypertrophy, in addition, "pulmonary P", II, III, aVF and right chest lead ST-T changes are also common The ECG is abnormal.

3. Echocardiography and Doppler ultrasonography Ultrasound diagnosis of cardiovascular disease Today's echocardiography can not directly measure the increased pulmonary artery pressure, but some indirect and characteristic ultrasound signs caused by increased pulmonary arterial pressure, pulmonary hypertension Judgment is quite helpful, and common signs are:

(1) Right ventricular hypertrophy and enlargement: Right ventricular hypertrophy is a direct consequence of chronic systolic overload, not only related to the degree and timing of pulmonary hypertension, but also related to the regulation of individual hypertrophic response, right ventricular free wall is light Degree of pulmonary hypertension has been thickened, ventricular septum is also thickened, the amplitude of motion is weakened, or in the same direction, 78% of patients with primary pulmonary hypertension have right ventricular enlargement, normal right ventricular free wall thickness 4mm, right ventricular diameter Less than 20mm.

(2) Pulmonary artery inner diameter widening and dilatation decline: two-dimensional and M-mode echocardiography can clearly show central pulmonary artery dilatation, normal main pulmonary artery inner diameter is less than 25mm, right pulmonary artery inner diameter is less than 18mm, pulmonary artery wall compliance decreases with increasing pressure The systolic expansion also becomes smaller.

(3) tricuspid and pulmonary valve regurgitation: cardiac enlargement and annulus dilatation can cause tricuspid and pulmonary regurgitation, Doppler echocardiography measured tricuspid regurgitation rate and reflux degree and angiography There is a good correlation between the two, but normal people have mild tricuspid regurgitation from 0 to 44%. Therefore, the significance of mild tricuspid regurgitation detected by Doppler echocardiography should be combined with other examinations. Steady, similarly, the incidence of pulmonary regurgitation in normal people is about 13% to 90%. The significance of detecting mild reflux should be comprehensively measured. The peak velocity and time limit of reflux in pulmonary hypertension increase, and change with pressure fluctuations. The reflux velocity is related to the diastolic pulmonary-right ventricular pressure difference.

(4) Pulmonary valve motion abnormality: In the early stage of pulmonary hypertension, M-mode echocardiography has noticed changes in pulmonary valve motion. Under normal circumstances, there is a small negative wave in the posterior segment of the late diastolic pulmonary valve, which is called a tilt and tight. After the P wave of the electrocardiogram occurs, it reflects that the right atrial contraction of the right pulmonary artery causes a small increase in the right ventricular-pulmonary pressure difference. When the pulmonary diastolic pressure is slightly increased, the "a" wave can be prevented from appearing. The normal "a" wave amplitude is averaged. 3 to 5 mm, less than 2 mm may have mild pulmonary hypertension. The disappearance of "a" wave usually indicates that the average pulmonary artery pressure is greater than 5.3 kPa (40 mmHg), but it should be noted that the "a" wave may reappear when the right ventricular end-diastolic pressure increases. The increase of pulmonary valve opening rate is another traditional ultrasound symptom of pulmonary hypertension. It is related to the difference of right ventricular-pulmonary pressure difference in early contraction, but not related to the absolute value of pulmonary artery pressure. The characteristic of M-mode echocardiographic pulmonary hypertension is The systolic notch or the W pattern reflects partial closure of the systolic phase of the pulmonary valve, with an incidence of approximately 60%. This sign is sometimes present in the absence of pulmonary hypertension. It may also appear.

(5) Common indicators for quantitative measurement of pulmonary artery pressure are:

1 Tricuspid regurgitation peak velocity has a good correlation with right ventricular systolic pressure, and the correlation coefficient is above 0.9.

2 The right ventricular outflow tract or main pulmonary artery blood flow acceleration or peak flow rate is advanced, and the correlation coefficient between blood flow acceleration time or peak time and ejection time ratio and pulmonary artery pressure is between 0.7 and 0.8.

3 M-mode echocardiography or Doppler flow signal measurement of right ventricular systolic time interval found in patients with pulmonary hypertension prolonged ejection, short ejection period, the ratio of the two increased, the latter is related to pulmonary artery pressure The coefficient is about 0.7, 80% of normal children's ratio is >0.3, and 90% of >0.4 of the average pulmonary artery pressure is >3.3 kPa (25 mmHg).

4 The right ventricular isovolumic relaxation time (pulmonary valve closure to tricuspid opening time) is prolonged. The relationship between isovolumic relaxation time and pulmonary systolic pressure is mainly determined by the decrease of right ventricular pressure between the closure of the pulmonary valve and the tricuspid opening. However, it is also affected by heart rate, right atrial pressure and diastolic rate, so it is more used for the identification of normal and mild pulmonary hypertension.

Although there are many quantitative pulmonary artery pressure ultrasound detection methods, the correlation coefficient is even higher than 0.9, but the interpretable pulmonary artery pressure variable is only about 0.6, so the "quantitative" examination can only be used as a reference. However, echocardiography and Doppler echocardiography is still a useful non-invasive method for the diagnosis of primary pulmonary hypertension.

4. Commonly used to exclude thromboembolic causes of pulmonary hypertension. Lung scans often show pulmonary or lobular perfusion defects, while pulmonary perfusion scan of primary pulmonary hypertension shows normal or diffuse sparse. It has been reported that lung scan can not explain further identification. True primary pulmonary hypertension (causal pulmonary artery disease) and multiple dumb pulmonary thromboembolism in pulmonary hypertension are of value, and the latter are often scattered irregular defects.

5. Pulmonary function and blood gas acid-base changes: Pulmonary function in patients with primary pulmonary hypertension is generally mildly restrictive ventilation disorder and diffuse dysfunction, no airway obstruction, early blood oxygen partial pressure can be normal, most patients have light, Moderate hypoxemia is the result of a decrease in mixed venous oxygen pressure caused by decreased cardiac output and imbalance of ventilation/perfusion ratio. Severe hypoxemia may be associated with open foramen ovale, almost all patients With respiratory alkalosis, pulmonary function tests are an insensitive test for the diagnosis of primary pulmonary hypertension.

6. Balloon-guided floating catheter examination: Primary pulmonary hypertension hemodynamics is defined as resting pulmonary artery mean pressure >25mmHg, or exercise >30mmHg, pulmonary capillary compression pressure is normal (12-15mmHg at rest), capillaries Pre-pulmonary hypertension grade (resting pulmonary artery mean pressure), mild: 26 ~ 35mmHg; moderate: 36 ~ 45mmHg; severe: > 45mmHg.

Usually the symptomatic primary pulmonary hypertension has a resting pulmonary artery mean pressure >45mmHg. The symptoms of early mild primary pulmonary hypertension are small, and there are few medical practitioners. It is difficult to obtain hemodynamic data in this period. Therefore, most patients have Hemodynamic characteristics are severe pulmonary hypertension, the average pulmonary artery pressure is usually increased by 3 times, about 8 ± 2.4 kPa (60 ± l8) mmHg, the range is 3.7 ~ 16.9kPa (28 ~ 127mmHg); right atrial pressure is light to moderate increase , 1.2±0.8 kPa (9±6) mmHg, range 03.9kPa (029mmHg); pulmonary capillary compression pressure is normal; cardiac index is slightly reduced, (2.27±0.9)L/(min·m) The range was 0.8-7.9L/(min·m). The hemodynamic data of 63 cases of pulmonary hypertension that could not be explained in our hospital were similar to the above. The mean mean pulmonary artery pressure was 8.7±0.3 kPa (65.1±2.4) mmHg, the average pulmonary artery. Systolic blood pressure was 13.6 ± 0.4 kPa (102.1 ± 3.3) mmHg, mean total lung resistance index was (33.2 ± 2.2) U / m; mean cardiac index was 2.29 ± 0.10L / (min · m), mean right atrial pressure was 1.4 ±0.1 kPa (10.4±0.9) mmHg, all data indicate that the patient was treated too late, and most of them had severe pulmonary hypertension and right heart dysfunction. Can not fail to affect the patient's treatment and prognosis.

Hemodynamic analysis found that the severity of the symptoms had little to do with the degree of pulmonary hypertension, which may be related to an increase in right atrial pressure and a decrease in cardiac output, both of which reflect right ventricular dysfunction and less than 1 time for symptoms. The average pulmonary artery pressure between the elderly and those older than 3 years is similar, indicating that the pulmonary arterial pressure has increased to a high level in the early stage of the disease. Only patients with labor dyspnea have severe pulmonary hypertension. The fatigue and edema reflect the right heart failure. In the late stage of the disease.

Diagnosis and diagnosis of primary pulmonary hypertension

Patients with primary pulmonary hypertension have an average survival of 4 years from the symptoms, and the hospital data is (5.9±0.7) years. There should be enough time for diagnosis and treatment, and even early diagnosis and timely treatment. Unfortunately, the rate of misdiagnosis outside the hospital is as high as 94%, the reason may be that the disease is not enough, because it is rare, it is often overlooked in the differential diagnosis; in addition, it may not be familiar enough with the diagnosis method and procedure of the disease, therefore, to improve the primary pulmonary artery The diagnostic level of high pressure, first of all based on improving the understanding of the disease, according to the diagnostic procedures to rule out all possible secondary pulmonary hypertension to determine the diagnosis.

The symptoms and signs of primary pulmonary hypertension are non-specific and can only suggest the possibility of pulmonary hypertension. Combined with chest X-ray, pulmonary function and arterial blood gas examination, it can basically exclude pulmonary arterial pressure secondary to pulmonary disease. Such as chronic obstructive pulmonary disease, pulmonary interstitial fibrosis, radionuclide lung ventilation / perfusion scan and pulmonary angiography can basically exclude large block of pulmonary thromboembolism, echocardiography and right heart catheterization for secondary Pulmonary hypertension of heart disease can be ruled out. Through the above examination, the cause of pulmonary hypertension is still unclear. Clinically, it can be diagnosed as unexplained pulmonary hypertension, mainly including plexus pulmonary artery disease (true primary pulmonary hypertension). Pulmonary thromboembolism and pulmonary venous occlusion, etc., the identification of them, although lung perfusion scan can help, but the only reliable method is open lung biopsy, for pathomorphological diagnosis.

Primary pulmonary hypertension is a plexus-induced pulmonary artery disease. Early lesions may be reversible, and there may be a possibility of improvement after treatment. Advanced progressive development and difficult treatment are important. Therefore, early diagnosis and early treatment are very important for prognosis.

As mentioned above, the misdiagnosis of the disease is quite common. According to the data of our hospital, 35% are misdiagnosed as congenital heart disease, including atrial septal defect, pulmonary stenosis, patent ductus arteriosus, trilogy of Fallot and Abbots malformation. Etc. Misdiagnosed as acquired heart disease accounted for 36%, including rheumatic heart disease, coronary heart disease, myocarditis, cardiomyopathy and pericarditis; misdiagnosed as chest and lung disease accounted for 12%, the above can be seen, can cause right heart enlargement Large cardiopulmonary diseases may be differentiated from primary pulmonary hypertension. As long as the understanding of primary pulmonary hypertension is improved in practice, all secondary pulmonary hypertension is excluded according to certain diagnostic procedures, and clinical diagnosis cannot be explained. The pulmonary hypertension is not very difficult either.

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