[A] 1.21 Thrombosis Flashcards
Define: Thrombosis
- A sold mass formed from blood constituents in a vessel or hear lumen during life
- Inappropriate formation of thrombus
Factors predisposing to thrombosis
Alterations in:
- Vascular endothelium
- Blood flow
- Blood constituents
Alterations in the vascular endothelium leading to thrombosis
- Vascular damage, endothelial injury
- Viral, bacterial, fungal, parasitic
- Immune-mediated vasculitis
- Exposure of collagen, release of inflammatory mediators
Alterations in blood flow leading to thrombosis
- Prestasis, stasis → Reduced flow
- Turbulence (caused by an aneurysm)
- Circulatory disturbances → Hypovolaemia, shock
- Cardiopathy → Cardiomyopathy
Alterations in blood constituents leading to thrombosis
- ↑ Number of platelets
- ↑ Adhesivity of platelets
- Changes in blood constituent proportion
- ↑ Conc. of aggregation promoting substances
- ↓ Conc. of anti thromboplastic substances
The appearance of thrombi depends on
- Underlying cause
- Location
- Composition
The significance of thrombi depends on their
- Location
- Ability to disrupt blood flow, perfusion
- Rate of formation/ size
List the forms of thrombus
- White/pale thrombus
- Red thrombus
- Mixed thrombus
- Hyaline thrombus (Fibrin thrombus in small vessels)
White thrombus
“Conglutination thrombus”
- Vascular damage
- Attachment of the thrombocytes
- Fibrin accumulation
- Grey-white mass attached to the endothelium
- Fibrin only
Red thrombus
“Coagulation thrombus”
- Composed of fibrin, thrombocytes & RBCs
- Seen in stasis
- Coupled with white thrombus
Red thrombus is usually accompanied by…
White thrombus
- In the case of obturation
- Before or after → Stasis of the blood
Red thrombus stasis for any reason can lead to…
- Heart failure
- Right side failure
- Tr. pulmonalis, lung
- Hypoalbuminaemia
- Cachexia, liver/kidney failure
Mechanism of thrombosis
- Stasis
- Plasma
- Higher viscosity
- Higher resistance the lumen
- Slowing down of blood flow
Hyalin thrombi
- Hypercoagulobility of the blood
- ↑ Thrombocytes, fibrinogen & globulins
- Substances causing thrombocyte aggregation
- Shock → Endotoxins
- Plasma or fibrin thrombi
- In the small blood vessels
- Arterioles, venules
- Terminal circulatory bed
Summarise DIC
Disseminated intravascular coagulopathy
- Pathologic activation of the clotting cascade
- Exposure of blood to tissues factor
Can be caused by septicaemic, toxaemia, shock, acidosis, necrosis
Forms of the thrombi
Mural thrombus (parietal with tail)
- White thrombus: Mural → occlusive
Occlusive thrombus
- Red thrombus
Outcomes of thrombosis
- Healing - After vessel injury
- Organ failure, sudden death
- Local/systemic circulatory disturbance
- Stenosis
- Heart
- Stenosis
- Cardiac valvular insufficiency
- Thromboembolism
Fate of the thrombus (generally)
- Complete elimination by fibrinolysis
- 1-2 days
- Colliquation
- By proteolytic enzymes of granulocytes
- By pyogenic bacteria
- Endothelisation
- Afer 1 week
Fate of a thrombus after 1 week
- Organisation, calcification
- Recanalisation (channel formation)
- Embolus formation
Thrombosis in species
- Horse: A. mesenterialis cran., abdominal aorta
- Cattle: Wall of the uterus
- Cat: Abdominal aorta
- Swine, cattle dog: Endocarditis
Mixed thrombi
- Changes in the circumstances
- White-red-white-red
Thrombosis of the lymph vessels
Plasma thrombi
