53. Thrombosis: definition of the concept, general and local factors of thrombus formation, stages of thrombus development. Types and structure of blood clots, their outcomes.

blood in the lumen of the vessel or in the cavities of the heart. Unlike a blood clot, postmortem clots are smooth, shiny, elastic, and lie freely in the lumen of the veins (they do not form at death from asphyxia). Stages of thrombosis:

1. Platelet agglutination: loss of platelets from the blood stream and adhesion to the site of endothelial damage → release of the agglutinating hyalomer of platelets (peripheral zone) → degranulation of platelets → release of thromboplastic factor and formation of active thromboplastin

2. Coagulation of fibrinogen and fibrin formation (the matrix for fibrin is the bare central zone of platelets - a granulomer containing a retractozyme of plates): pro-thrombin + active thromboplastin + Ca2+ ions → thrombin + fibrinogen → fibrin monomer + fibrin-stimulating factor → fibrin polymer → retraction ("compression") of a clot with the participation of a retractozyme

3. Erythrocyte agglutination: attachment to a fibrin clot and gluing of erythrocytes

4. Plasma protein precipitation: deposition of plasma proteins on an existing convolution. Factors of thrombosis:

a) Local factors:

1. vascular wall changes (endothelial damage, vasculitis in infections, atherosclerosis and plaque ulceration, vascular spasms in hypertension)

2. slowing down and disruption (turbulence) of blood flow (more often blood clots in the veins of the legs, with decompensation of HF - congestive blood clots; formation of blood clots in the bifurcation sites)

b) common factors:

1. violation of the regulation of the coagulation and anticoagulation systems of the blood (activation of the coagulation system after surgery in response to injury)

2. changes in blood composition (increased fibrinogen content, platelets, changes in blood viscosity and rheology in hemoblastosis, autoimmune diseases)

3. The thrombus is usually attached to the vessel wall, the surface is corrugated, dense, dry, consists of branching beams of glued platelets and bundles of fibrin with erythrocytes and leukocytes located between them.

Classification of blood clots by morphology:

a) a white blood clot - platelets + fibrin + leukocytes - forms slowly with fast blood flow (arteries)

b) red thrombus - trobocytes + fibrin +erythrocytes - forms quickly with slow blood flow (veins)

c) mixed (layered) thrombus - has a layered mottled structure, consists of a head (the structure of a white thrombus attached to the endothelium), a body (actually a mixed thrombus) and a tail (the structure of a red thrombus) - more often in the veins, in the cavities of the aortic aneurysm and heart

d) hyaline thrombus - platelets+erythrocytes+precipitating plasma proteins - in ICR cells

Blood clots:

1. parietal - most of the lumen is free - often on the endocardium, in the ears, in large arteries with atherosclerosis and

2) occluding (obstructing) - more often in veins and small arteries

Depending on the height:

1. progressive thrombus - grows along the blood flow

2. spherical thrombus - a "polished" thrombus in the heart cavity

3) dilated thrombus - a thrombus in aneurysms

Outcomes of thrombosis:

1. favorable:

1. aseptic autolysis of a thrombus

2. organization of a thrombus

3. channeling of a thrombus - the appearance of cracks or channels lined with endothelium in a thrombus

4. coagulation of a thrombus - the transformation of channels lined with endothelium into vessels

5. formation and petrification of a thrombus (the appearance of phlebolites)

b) unfavorable:

1. separation of the thrombus and its parts → thromboembolism

2. septic melting of the thrombus and thrombobacterial vascular embolism in sepsis.