Etiology and pathogenesis of nonspecific aortoarteritis

Etiology and pathogenesis of nonspecific aortoarteritis

The etiology is unknown. The combination with diseases such as rheumatoid arthritis, ankylosing spondylitis, ulcerative colitis, suggests the possibility of an autoimmune nature. It is assumed that the disease is associated with tuberculosis, streptococcal infection.
A partial or generalized lesion of the ascending and (or) descending aorta and its branches, sometimes the pulmonary artery, is observed . The middle and outer shell of the vessel or all of the membranes ( panarteritis ) are affected . Infiltration by lymphocytes, plasma cells, histiocytes, sometimes neutrophils and multinuclear giant cells is characteristic. In the terminal stages, the infiltrates disappear, fibrosis develops. Thickening of the inner membrane and fibrosis of the middle and outer membranes lead to a narrowing or obliteration of the lumen of the vessel. There may be aneurysms, stratification of the vessel wall, sometimes with its rupture. Sometimes the aortic valve and coronary vessels are affected, the aortic opening becomes dilated, which leads to aortic insufficiency.

Clinic of nonspecific aortoarteritis

At an early stage, systemic signs are noted – fatigue, weight loss, low fever, arthralgia, or moderate synovitis . Later, ischemic symptoms appear – a decrease in heart rate and (or) noise. The upper limbs become cold, weakness in the arms develops, rapid fatigue, intermittent claudication, pain along the vessels. Dizziness and fainting are often observed, especially when moving from horizontal to vertical, as a result of occlusion of the carotid arteries. Nausea, headache, blurred vision, or ischemic ulcers; narrowing of the aorta or renal larter can lead to arterial hypertension. II far-reaching cases of arterial insufficiency can cause atrophy and ulceration of the skin on the face, scalp, hair and (or) forehead loss, dementia, abdominal pain, myocardial ischemia. Ruptured aneurysms or stratified arteries can lead to sudden death.
During the examination, the determination of the pulse on the radial, brachial, carotid arteries, aorta, auscultation of large vessels, blood pressure should be measured on both arms and legs is of primary importance. Characteristic asymmetric weakening or disappearance of the pulse on the hands, asymmetry of blood pressure. Over stenotic vessels, a rough systolic murmur can be heard. More than half of patients with increased blood pressure.
Collateral circulation can be detected on the shoulders or elsewhere. Aortic insufficiency may be observed. In the active phase of the disease, ESR is increased, moderate anemia may be noted. The white blood cell count is usually normal or slightly elevated. Serum gamma globulins are often elevated.

Diagnosis and differential diagnosis of nonspecific aortoarteritis

At an early stage of the disease, when there are only general nonspecific symptoms (weight loss, fever, arthralgia), it is difficult to make a diagnosis, but the possibility of aortoarteritis should always be considered when developing such symptoms in a young woman. Recognition of aortoarteritis in such cases is based on the detection of noise or decreased heart rate in large arteries. With an expanded picture of the disease, the diagnosis is based on the detection of cerebral ischemic syndrome, ischemic lesion of the extremities with a decrease in heart rate in large vessels, and vasorenal hypertension.
The diagnosis is confirmed by angiography or dopplerography, rheovasography . On arteriogram reveals narrowing – or patchy throughout the valley – vascular segments, expanding areas. These changes are more often observed in the proximal aorta and its branches. The affected arteries are usually too large to biopsy, but they must be examined with surgical intervention.
Differential diagnosis is carried out with arthritis observed with rheumatism, ankylosing spondylitis, Reiter’s disease, syphilis, vasorenal hypertension with atherosclerosis and fibromuscular dysplasia of the renal vessels.

Etiology of embolism

In 92–95% of patients, the causes of arterial embolism are heart diseases and, first of all, myocardial infarction (especially in the first 2-3 weeks of illness), complicated by severe cardiac arrhythmias, acute or chronic left ventricular aneurysm. Cause emboli may be combined rheumatic mitral heart disease with a prevalence of stenosis complicated intraatrial thrombosis due to atrial arrhythmia. Subacute bacterial endocarditis and congenital heart defects lead less often to arterial embolism. Sources of emboli can be aneurysms of the abdominal part of the aorta and large main arteries (in 3-4% of patients with embolism), ulcerative atheromatosis of the thoracic and abdominal parts of the aorta.

Embolism pathogenesis

As a rule, emboli are localized in the area of ​​branching or narrowing of the arteries. Embolism is accompanied by a pronounced reflex arterial spasm, responsible for the formation of an extended thrombus, which blocks the collateral network. With thrombosis and embolism of the main arteries of the limbs in the corresponding vascular pools, acute tissue hypoxia occurs, the main cause of which is a violation of blood flow in the vessels of the microvasculature. In the affected tissues, an excess of under-oxidized metabolic products is formed, which leads to the development of metabolic acidosis. The latter promotes platelet adhesion and the formation of platelet aggregates in the capillary lumen , exacerbating the severity of ischemia.
The increase in hypoxia adversely affects the course of redox processes in the tissues. They increase the content of membrane – toxins – histamine, serotonin, kinins , prostaglandins , which increase the permeability of cell membranes and intracellular membranes. As a result of impaired cellular permeability, subfascial edema of the muscles appears , in which the blood flow deteriorates even more due to compression by the bone-fascial cases. Changes in bone metabolism and cell death lead to the breakdown of lysosomes with the release of hydrolases that lyse tissues. The consequence of this is the development of soft tissue necrosis. From the ischemic tissues in the bloodstream fed suboxide – lennye metabolic products resulting in metabolic acidosis, toxic products, potassium, myoglobin. Severe disturbances in the activity of the cardiovascular system occur, manifested by a deterioration in cardiac activity, heart rhythm disturbances, and gross changes in central hemodynamics. Circulatory hypoxia increases, and renal filtration decreases.

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