Pulmonary arteriovenous aneurysm

Introduction to pulmonary arteriovenous tumor Pulmonary arteriovenous stenosis is a congenital pulmonary vascular malformation. The blood vessels are enlarged or distorted or form a cavernous hemangioma. The pulmonary blood flows directly into the pulmonary vein without passing through the alveoli. The pulmonary artery and the vein directly communicate with each other to form a short circuit. In 1897, it was first discovered by Churton. Pulmonary aneurysm. In 1939, Smith applied cardiovascular angiography to confirm the disease. The literature was named more, such as pulmonary arteriovenous tumor, pulmonary vasodilatation (haemagiectasisoft helung), telangiectasia with pulmonary aneurysm (haemonreactelangiectasia with pulmonaryarteryaneurysm). In addition, the disease is familial and is associated with genetic factors such as hereditary hemorrhagic telangiectasia (Rendu-Osler-Weber disease). basic knowledge The proportion of illness: 0.035% Susceptible people: no special people Mode of infection: non-infectious Complications: atelectasis, hemothorax, acute myocardial infarction

Causes of pulmonary arteriovenous tumor

Types of:

This malformation is directly connected by a variety of different sizes and unequal numbers of pulmonary arteries and veins. Common arteries are 1 branch and 2 veins. There is no capillary bed between them. The muscular wall of the diseased vessel wall is poorly developed and lacks elasticity. Fiber, and pulmonary artery pressure promotes the progressive expansion of the diseased blood vessels. Pulmonary arteriovenous tumor is a direct type of pulmonary arteriovenous branch, which is characterized by vascular distortion, expansion, thin arterial wall, thick vein wall, and cystic enlargement. Tumors are separated, visible thrombosis, lesions can be located in any part of the lungs, thickening of the tumor wall, but a certain area of the endothelial layer is reduced, degeneration or calcification, causing rupture, and direct right pulmonary artery and left atrium direct traffic, for rare special Types of.

distributed:

The lesions are distributed in one or two lungs, single or multiple, the size can be 1mm or involve the whole lung, the common sub-pleural area of the right and the second lower lobe and the right middle lobe. About 6% of the disease is accompanied by Rendu- Osler-Weber syndrome (multiple arteriovenous fistula, bronchiectasis or other malformations, lack of right lower lobe and congenital heart disease).

Pathophysiology:

The main pathophysiology is that venous blood flows from the pulmonary artery into the pulmonary artery, and its partial flow can reach 1889%, so that the arterial oxygen saturation decreases, generally no ventilation disorder, PCO2 is normal, and most cases cause erythrocytosis due to hypoxemia. Because of the lungs, body circulation direct traffic, prone to bacterial infections, brain abscess and other complications.

Pulmonary arteriovenous prevention

The disease is a group of congenital pre-diseases, so the prevention of this disease is mainly the prevention of its complications, the main complications after pulmonary arteriovenous fistula resection can occur before, during and after surgery, as long as Take positive measures that can be prevented or reduced.

Pulmonary arteriovenous complications Complications of atelectasis and acute myocardial infarction

1. The complications of pulmonary surgery after pulmonary arteriovenous fistula are as follows:

(1) atelectasis

Mainly due to postoperative cough and weakness, bronchial endocrine secretions and small clots are not well discharged, causing bronchial obstruction, patients feel shortness of breath or hernia, auscultation of local lungs weak or disappeared, the trachea can be biased to the affected side, bedside chest X-ray The fluoroscopy can be confirmed. After the operation, the patient should be encouraged and assisted to make effective cough, coughing up the bloody sputum that blocks the bronchus, and the sputum is not easy to cough up. The mucosolvan 15mg plus distilled water 30ml can be inhaled twice a day. If unsuccessful, insert a rubber catheter through the nostrils, pass the glottis to the trachea, gently move back and forth to stimulate the tracheal mucosa, cause the patient to have a reflex cough, and cough up. If unsuccessful, bedside fiberoptic bronchoscopy is required. And attraction, generally can make the lungs re-expand.

(2) empyema

Causes: (1) Inadvertent operation during operation makes cancer, abscess or tuberculosis cavity collapse, contaminating the chest cavity, such as not completely flushing the chest before closing the chest or the patient's body is very weak, low resistance, the pleural cavity can be infected into pus chest. (2) After the pneumonectomy, the bronchospasm on the surface of the residual lung, such as the rough surface after the lung segment resection and the lung suture edge after the wedge resection, does not close the healing for a long time, it is easy to infect the pleural cavity to form empyema, especially postoperative respiratory insufficiency. When a ventilator is needed for continuous assisted breathing, the fistula is more difficult to heal due to a certain pressure in the lungs. It is easy to form an empyema for a long time. Once the hyperthermia forms an empyema, it should be closed early or thoracic puncture. Re-expand the lungs and close the abscess.

(3) Blood chest

Causes: (1) Hemorrhage or hemorrhage at the pleural adhesion. (2) Hemorrhage after vascular injury of the chest wall is difficult to stop bleeding due to high pressure from the systemic circulation. (3) Large blood vessel damage in the lungs, mostly due to ligature detachment, rapid bleeding, often no time to rescue, re-opening the chest to stop bleeding; (1) postoperative thoracic closed drainage tube blood volume > 300ml / h, or 5h The internal average > 200ml / h; (2) The blood drawn out quickly solidified, indicating a large active bleeding in the chest. (3) There is a large density increase on the affected side of the chest X-ray. The lungs are compressed and the mediastinum is displaced to the healthy side. The patient feels difficulty breathing, indicating that there are more clots in the chest and need to be removed. (4) The patient has hemorrhagic shock. Although he has lost blood and taken anti-shock measures, the symptoms of blood loss have not improved. In any of the above situations, he should immediately cooperate with the doctor for treatment, and quickly establish an intravenous channel to infuse hemostasis drugs. Closely observe blood pressure, pulse, breathing, prepare for rescue, and prepare enough whole blood at the same time, strive for early chest exploration and stop bleeding.

(4) Bronchial pleural fistula

It usually occurs 7 to 10 days after surgery. The patient's irritating cough is obvious. The sputum often has old blood, and the patient's liquid pneumothorax appears. The pleural puncture results in infectious content similar to that of coughing. After puncture, 2ml of blue is injected into the thoracic cavity. Liquid, if coughing out blue-stained sputum, it is further confirmed as sputum. Once bronchospasm occurs, it will soon infect the thoracic cavity to form empyema. It is necessary to perform closed thoracic drainage and systemic antibiotic treatment to control infection. .

(5) Respiratory insufficiency

It mainly occurs in patients with poor preoperative lung function. Because the cancer needs to be pneumonectomy, there should be sufficient estimation and preparation before the operation. After the thoracotomy is completed, the tracheotomy is performed on the operating table, and the return to the ward is Start breathing with a ventilator, usually 5 to 7 days after the ventilator can be removed, if the preoperative lung function is better, postoperative due to more lung secretions, poor cough, or inflammation of the lungs caused by respiratory insufficiency, The tracheotomy should be performed at the bedside as soon as possible, and the ventilator should be connected for auxiliary breathing.

(6) Circulatory system accident

After the pneumonectomy, the death of the circulatory system accounted for about 015% of the total number of resections, mostly due to acute myocardial infarction or pulmonary embolism. This accident is not proportional to the extent of lung resection, and occurs mostly in the lobe or segment. After resection, some patients had no history of heart disease before surgery. The family members and doctors were unprepared in their minds. They suddenly occurred without any warning at 3 to 5 days after surgery. There were few people who could be rescued and resurrected.

2, other common serious complications are pulmonary arteriovenous rupture, thoracic hemorrhage, bacterial endocarditis, brain abscess, embolism and so on.

Pulmonary arteriovenous fistula sometimes causes hemoptysis, other symptoms of chest pain, hemoptysis is caused by rupture of telangiectasia lesions in the bronchial mucosa or rupture of pulmonary arteriovenous fistula. Chest pain may be located in the lung submucosa or blood due to rupture of the lesion. Caused by chest, about 25% of cases have neurological symptoms, such as convulsions, language disorders, diplopia, temporary numbness, etc., which can be due to erythrocytosis, hypoxemia, vascular embolism, brain abscess and cerebral telangiectasia Caused by familial hereditary hemorrhagic telangiectasia often have bleeding symptoms, such as nasal discharge, hemoptysis, hematuria, vaginal and gastrointestinal bleeding, due to the presence of sputum can also be complicated by bacterial endocarditis, Careful auscultation in the lesion area, about 50% of cases can hear systolic murmur or two-stage continuous murmur, which is characterized by murmur with inhalation enhancement, weakened exhalation, and other clubbing toes, red blood cells, increased hematocrit , arterial oxygen saturation decreased.

Pulmonary arteriovenous symptoms common symptoms telangiectasia dizziness pulmonary arteriovenous fistula chest pain fatigue

Main pathological changes and clinical features of pulmonary arteriovenous fistula

(1) pathological changes

The main pathological changes of pulmonary arteriovenous fistula are direct communication between the arteriovenous vessels in the lungs, incomplete development of the vascular septum separating the arteries and venous plexus or capillary defects in the peripheral nerves of the lungs, forming a short circuit between the arteries and veins, and short-circuiting the blood vessels to the arterial pressure load. The role of the gradual expansion, the formation of cystic sputum, pulmonary hypoxemia through the fistula without oxygenation directly reflux left heart into the systemic circulation, there are reports in the literature, when the flow rate is greater than 25%, the child appears fatigue, shortness of breath after activity, dizziness, hypoxia, etc. Symptoms, if the flow rate is large and the elderly history may appear purpura, clubbing / toe and secondary erythrocytosis, increased hematocrit, increased Hb, increased blood viscosity, easy to form small thrombus in the pulmonary blood vessels can be produced Cerebral thrombosis or brain abscess, PAVF rupture or embolus involving the bronchial wall may cause hemoptysis and hemothorax after erosion. The disease is more common, and the multiple lesions account for 5% to 10%, which can occur in any part of the lung tissue, but half of them The above occurs in the right lower lobe, and more cystic bulges or cystic changes in the visceral pleural sac can be seen during the operation.

(2) Main clinical manifestations

1 The disease is more common in young people, and the small flow rate can be asymptomatic. It is only found in the X-ray examination of the lungs. The large flow rate can cause shortness of breath after activity, purpura, but more often in childhood, occasionally in newborns. Most patients have purpura from childhood, which gradually increases with age and has difficulty breathing.

225% of patients had neurological symptoms such as convulsions, ataxia, and diplopia.

335% to 50% of patients have familial hereditary hemorrhagic telangiectasia symptoms such as epistaxis, hemoptysis, hematuria, and gastrointestinal bleeding.

4 When the pulmonary arteriovenous fistula ruptures, the patient may have chest pain and hemothorax.

5 If the sputum is large, the systolic or continuous murmur can be heard at the location of the sputum.

6 X-ray chest radiographs are characterized by one or more circular shadows in one or both lung fields, and the size of the heart shadow is normal. CT scan of the lungs can be seen to affect the expansion of the pulmonary arteries and veins. ,distortion.

7 right heart catheter showed decreased arterial oxygen saturation. Selective pulmonary angiography showed that pulmonary arteriovenous fistula was developed earlier than normal pulmonary vein system, pulmonary angiography agent was delayed, and pathological changes in early left atrial development were observed.

Pulmonary arteriovenous examination

(1) X-ray performance

It is characterized by isolated or multiple rounded shadows, varying diameters of shadows, uniform density, clear edges, or shallow lobes; dilated and thickened feeding arteries and drainage veins connected to the shadow, and the blood supply artery is connected to the hilar; The shadows generally do not increase or only slowly increase. According to the above characteristics, most of the cystic PAVMs can be combined with clinical data to make a definite diagnosis. The diagnosis of atypical flat films is difficult, such as complicated multi-blood cystic pulmonary arteriovenous fistula. The flat film is characterized by a large dense shadow. It is difficult to make a correct diagnosis based on the X-ray film. The diffuse pulmonary arteriovenous fistula is often lacking the typical X-ray film sign, which can be expressed as a spotted shadow in the lung or lung segment. It can be expressed as enhanced lung texture and distortion. In some cases, there is no positive radiograph. Therefore, diffuse pulmonary arteriovenous fistula and X-ray plain film are difficult to diagnose.

(2) pulmonary angiography

Pulmonary angiography is a reliable method for the diagnosis of PAVMs. Pulmonary angiography can identify the location, extent, extent and extent of the lesion, and provide a basis for the choice of clinical treatment. The angiographic method is divided into selective or superselective pulmonary angiography. Sexual pulmonary angiography, orthotopic projection, including the entire lung field of the lungs in order to avoid missing lesions. After selective main pulmonary angiography, superselective pulmonary angiography is determined depending on the situation. The author usually places the catheter in the blood supply artery. Superselective angiography, select the appropriate angle when investing, such as right lung lesion selection right anterior oblique position (15 ° ~ 20 °) projection, left lung lesion selection left anterior oblique position (15 ° ~ 20 °) projection, mainly Performance: simple cystic PAVMs can be seen with the filling of the pulmonary sac with pulmonary artery development, drainage pulmonary vein development is earlier than normal pulmonary veins, blood supply artery and drainage vein are both, and see different degrees of tortuous expansion, larger tumor capsule visible contrast agent Delayed emptying, complex cystic PAVMs can be seen in 2 or more blood supply arteries and drainage veins, visible separation in the tumor capsule, contrast agent emptying is obviously delayed, Mi Diffuse pulmonary arteriovenous fistula showed multiple "grape bunch"-like small blood pool filling, and the pulmonary veins in the lesion site were developed in advance.

(3) Cardiac catheterization and cardiovascular angiography

Arterial oxygen saturation decreases, cardiac output and cardiac chamber pressure are normal and there is no intracardiac shunt. Pigment dilution test can be used to test the flow rate and location, pay attention to avoid catheter into the sputum, alert to the risk of rupture, and inject contrast agent in the pulmonary artery. Shows the location and size of the arteriovenous fistula, showing dilated, elongated, distorted blood vessels.

(4) Echocardiographic contrast echocardiography and pulmonary perfusion radionuclide scanning can correctly diagnose PAVMs, but the former cannot determine the location and extent of the lesion. Although the latter can determine the location and extent of the lesion, it cannot observe the specific anatomical details. Magnetic resonance and spiral CT are used for the diagnosis of PAVMs. It is considered that spiral CT and its three-dimensional reconstruction are superior to pulmonary angiography in the correct diagnosis and anatomy of PAVMs.

Diagnosis and diagnosis of pulmonary arteriovenous tumor

diagnosis

The diagnosis and treatment of this disease should pay attention to medical history and physical examination. Children with or without nasal discharge and limbs, facial and back telangiectasia, and history of cerebral ischemia. More than 50% of patients with pulmonary arteriovenous fistula can be combined with hereditary hemorrhage. For telangiectasia, it has been reported that congenital pulmonary arteriovenous fistula is familial. There are many preoperative methods for this disease: NaHCO3 venography is simple and reliable, and most common chest X-rays are normal. In patients with PAVF, single or multiple opaque shadows can be found. Enhanced CT and MR examination can determine the lesion. Pulmonary angiography is the most reliable method of diagnosis. It can confirm that the source of arterial blood supply is pulmonary artery, and a few can also be from the systemic circulation. There is no typical X-ray sign of arteriovenous fistula in the lung. It is not uncommon in clinical practice. The pulmonary arteriovenous fistula is developed earlier than the normal pulmonary vein system, the pulmonary angiography agent is delayed in emptying, and the pathological changes in the early development of the left atrium.

Differential diagnosis

In clinical terms, the disease can be divided into three types, namely:

Type I multiple telangiectasia: diffuse, multiple, formed by capillary terminal anastomosis, and its short-circuit flow is large.

Type II pulmonary aneurysm: formed by an anastomosis of a larger vascular in the proximal center. The tumor is dilated due to pressure factors, and the short-circuit flow is larger.

Type III pulmonary artery and left atrial communication: The pulmonary artery is significantly enlarged, and the short-circuit flow is extremely large. The right-to-left flow can account for 80% of the pulmonary blood flow, often accompanied by abnormalities of the lung and bronchus.

Clinically, the disease needs to be differentially diagnosed with the following diseases:

(1) intrapulmonary metastases

Pulmonary arteriovenous fistula, especially multiple pulmonary arteriovenous fistula, its chest CT shows multiple lesions in the lungs, which are easily misdiagnosed as intrapulmonary metastases. It should be identified according to its medical history and blood gas analysis. In particular, we must distinguish the difference between the two on CT.

(2) Tuberculosis

The main distinguishing points of PAVF and other types of tuberculosis are:

(1) Tuberculosis often has symptoms of fever, anorexia, fatigue, night sweats, etc., while PAVF is rare.

(2) The rate of red blood cell sedimentation and white blood cells in patients with active tuberculosis are mild to moderately elevated, while PAVF generally has no significant changes.

(3) PPD test in tuberculosis patients is more positive, while PAVF is generally negative.

(4) The lesions on the chest X-ray of patients with pulmonary tuberculosis are mostly located in the upper lobe of the lung, the posterior segment or the dorsal segment of the inferior lobe, and the PAVF is often located in the anterior pleural visceral layer of the lower and middle lobe.

(5) Pulmonary tuberculosis patients were more positive for anti-antacid bacteria, while PAVF patients were negative. In addition, after anti-tuberculosis treatment, the symptoms of tuberculosis patients improved quickly. Re-examination of X-ray films (or chest CT) showed that there were lesions. Absorption, but there were no significant changes in the symptoms and lung lesions of PAVF patients.

(3) Bronchiectasis

Bronchiectasis and pulmonary arteriovenous fistula have many similarities in clinical symptoms, such as repeated coughing and hemoptysis. Therefore, the two should be identified in clinical diagnosis. Generally speaking, if there are the following characteristics, the lung should be considered. Arteriovenous fistula:

1 One or more round or oval-shaped masses with uniform density can be seen on the chest radiograph. The boundary is clear and there are signs of lobulation. Sometimes, two cord-like shadows are visible at the proximal end of the mass to connect with the hilum. This is the lung. The flow of arteriovenous fistula into and out of the blood vessels.

2 Pulmonary vascular pulsation can be seen under fluoroscopy, and the Valsalva operation method (continuous and forced exhalation of the closed glottis) is increased by the intrathoracic pressure, and the blood flowing into the chest cavity is reduced, and the circular shadow is significantly reduced.

3 patients may have purpura, clubbing (toe) and erythrocytosis, confirmed pulmonary angiography, can see the size, location and number of blood vessels.

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