Overview of pulmonary arteriovenous tumors
Pulmonary arteriovenous aneurysm, for congenital pulmonary vascular malformation vascular enlargement tortuous or form cavernous hemangioma, the pulmonary artery blood does not pass through the alveoli directly into the pulmonary veins, the pulmonary artery and vein directly connected to the formation of a short circuit. 1897 by the Churton first discovery described as multiple pulmonary arteriovenous aneurysms.
Etiology
This malformation is by a variety of different sizes and an unequal number of pulmonary arteries and veins directly connected to the common arteries 1 branch, veins 2 branches, there is no capillary bed between the two, the lesion of the wall of the blood vessel myocardium dysplasia, the lack of elastic fibers, but also because of the pressure of the pulmonary artery prompted by the lesion of the blood vessel to progressive dilatation, the pulmonary artery and vein aneurysm is a type of pulmonary artery and vein branches of the direct traffic type, the manifestation of the blood vessels are twisted, dilatation, the arterial wall thickness, vein wall thickness, tumor is a sac. Venous wall is thick, the tumor is cystic enlargement, the tumor is separated from the tumor, visible thrombus, the lesion can be located in any part of the lung, the tumor wall is thickened, but the endothelial layer in a certain area is reduced, degeneration or calcification, which leads to rupture of the cause, and there is a direct traffic between the right pulmonary artery and the left atrium, which is a rare and special type.
Symptoms
1. The disease is mostly seen in young people, those with small fractional flow can be asymptomatic, only found in lung X-ray, those with large fractional flow can have shortness of breath and cyanosis after activity, but most of them appear in childhood, occasionally seen in newborns, most of the patients have cyanosis from childhood, and it is gradually aggravated with the growth of age and has respiratory distress.
2.25% of patients have neurological symptoms such as convulsions, ataxia, diplopia.
3.35%～50% of patients have familial hereditary hemorrhagic capillary dilatation symptoms, such as epistaxis, hemoptysis, hematuria, gastrointestinal bleeding.
4. When pulmonary arteriovenous fistula ruptures, patients may have chest pain and hemothorax.
5. If the fistula is large, systolic or continuous murmur can be heard at the site of fistula.
6. X-ray chest radiographs are characterized by one or more rounded shadows of varying sizes in one or both lungs, while the heart shadow is normal in size; CT examination of the lungs shows that the affected pulmonary arteries are dilated, prolonged and distorted.
7. Right heart catheterization shows reduced arterial oxygen saturation, selective pulmonary arteriography can show pulmonary arteriovenous fistula earlier than the normal pulmonary venous system, delayed emptying of pulmonary angiographic agent, left atrial early visualization of pathological changes.
Examination
1. X-ray manifestations
The manifestation of isolated or multiple round-like shadows, the shadow diameter varies in size, uniform density, clear margins, or shallow lobulation; dilated and thickened blood-supplying arteries and draining veins connected to the shadow, blood-supplying arteries are connected to the hilum; the shadow usually does not increase or only slowly increases, according to the above characteristics, combined with clinical data, most of the cystic pulmonary arteriovenous fistula can be clearly diagnosed.
2.Pulmonary arteriography
Pulmonary arteriography is a reliable method to confirm the diagnosis of pulmonary actinic aneurysm. Pulmonary arteriography can clarify the location, morphology, extent and degree of involvement of the lesion, and provide the basis for the choice of clinical treatment. The method of arteriography can be divided into selective or super-selective pulmonary arteriography, and selective main pulmonary arteriography can be carried out first.
3. Cardiac catheterization and cardiovascular angiography
The arterial oxygen saturation is decreased, the cardiac output and cardiac chamber pressure is normal and there is no intracardiac shunt, pigment dilution test can be used to test the shunt flow and site, pay attention to avoid the catheter into the fistula, be alert to the risk of rupture, in the pulmonary artery injection of contrast medium can show the site and size of the arteriovenous fistula, can be seen to be dilated, elongated, twisted blood vessels.
4.Echocardiography and lung perfusion nuclear scanning
Can make correct diagnosis of pulmonary arteriovenous tumors, but the former can not determine the location and scope of the lesion, the latter can determine the location and scope of the lesion, but can not observe the specific anatomical details, in recent years, magnetic resonance and spiral CT is used for the diagnosis of pulmonary arteriovenous tumors, some people think that spiral CT and its three-dimensional reconstruction of pulmonary arteriovenous tumors correct diagnosis and anatomical display is better than that of pulmonary arteriography.
Diagnosis
The diagnosis and treatment of this disease should pay attention to the history and physical examination, whether the child has epistaxis and epistaxis and capillary dilatation of the limbs, face and back, and whether there is a history of cerebral ischemia, some patients with pulmonary arteriovenous fistula can be combined with hereditary hemorrhagic capillary dilatation, and there are also reports of familial congenital pulmonary arteriovenous fistulas, and there are many preoperative methods of examination of the disease: cardiac ultrasonography to monitor the NaHCO3 venography is simple and diagnostic, and the common X-ray chest film is mostly normal, cystic pulmonary arteriovenous fistula cases can be found single or multiple opaque shadows, enhanced CT and MR examination can determine the site of the lesion, pulmonary angiography is the most reliable method of confirming the diagnosis, can confirm that the source of arterial blood flow for the pulmonary artery, a few can also come from the circulation, diffuse intra-pulmonary arteriovenous fistulas do not have the typical X-ray signs, clinically is not uncommon, the pulmonary arteriovenous fistulas than the normal pulmonary venous system Early visualization of pulmonary arteriovenous fistulas compared with the normal pulmonary venous system, delayed emptying of pulmonary angiographic agents, and early visualization of the left atrium are pathological changes.
Treatment
All symptomatic patients with limited lesions require surgical treatment. Even if there are no obvious symptoms, all should be treated surgically because of the progressive lesions, which can have lethal complications such as rupture, hemorrhage, bacterial endocarditis, brain abscess, and embolism. Surgery is contraindicated except for very small fistulas or diffuse involvement of both lungs. Infants and young children who are not severely symptomatic may be operated on in childhood. There are two main options for the treatment of this disease:
1. Embolization
It is a non-surgical treatment that has been pioneered in recent years with the advances in cardiovascular interventional radiology techniques, and the number of reports in the literature is gradually increasing. The most commonly used embolization materials are stainless steel spring coils, followed by balloons, tissue adhesives, absorbable gelatin sponges, and silicone plastic pellets. Since the embolic material cannot be removed once it is placed in the vessel, it should be accurately positioned before placement. The advantage of this method is that it does not open the chest and preserves more lung tissue; the disadvantage is that the embolization needs to be positioned under X-ray, inaccurate embolization or dislodgement of the embolization leads to embolization complications, which can easily lead to pneumonia, and it is more costly and prone to recurrence if the treatment is not complete. Therefore, whether embolization is the first choice is still controversial. However, multiple extensive diffuse pulmonary arteriovenous lesions are contraindicated for surgery, and may be considered for embolization by applying ultra-small stainless steel coils accurately placed in the branches of pulmonary arteriovenous branches leading to the fistula.
2. Surgical treatment
Single pulmonary arteriovenous fistula, can wedge resection of the lesion, or lobectomy / segmental resection, in principle, as far as possible to retain the most normal lung tissue. But still need to pay attention to the blood supply of the lesion lung, pulmonary arteriovenous fistula deformity can have a variety of variants, in the pathology section of the malformation of the blood vessels found in a variety of variants, some lesions of the lung tissue is small, it is difficult to find intraoperative, easy to recur after surgery. It has been reported in the literature that intraoperative ultrasound can accurately find tiny foci of arteriovenous malformations that are invisible to the naked eye and assist in locating and resecting diseased tissue.