Hemodynamic disorders - 2 Flashcards
When can we see the blood clot?
A. extravascularly during life
B. within the cardiovascular system after death (post mortem blood clot)
What is a thrombus?
- mass of clotted blood formed within cardiovscular system during life that appear only in pathological conditions.
What are the main causes of thrombus and what are they called collectively?
Virchow’s Triad
- Interrupted blood flow (stasis)
- Endothelial injury
- Hypercoagulability
What are the causes of Interrupted blood flow?
– Stasis • venous circulation • cardiac chambers • arterial aneurysms – Turbulent flow • arterial circulation • endothelial injury
What diseases may cause stasis and predispose to thrombosis ?
- hyper-viscosity (e.g., polycythemia)
* deformed Erythrocytes (e.g., sickle cell anemia)
What are the causes of endothelial injury?
–Trauma to endothelial cells (e.g., Hypertension, Burns)
– Infections (e.g., endocarditis, ulcerated atherosclerotic plaque)
– Foreign material (e.g., hypercholesterolemia, smoking)
What are the causes of Hypercoagulability ?
• Genetic
–Factor V (Leiden) mutations
-Prothrombin mutation
–Antithrombin III deficiency
• Acquired
–Heparin-induced thrombocytopenia –Cigarette smoking
–Antiphospholipid antibody syndrome –Obesity
–Prolonged immobilization –Malignant neoplasms
–Oral contraceptives
What is the difference between the post mortem clot and thrombus?
- blood clot: moist, smooth lacks attachment to its wall, and It can be red or yellow.
- thrombus: dry, matt mass, closely adhering to its wall, and from gray to red.
- both are similar under microscope: consist of fibrin framework with erythrocytes, leukocytes, and platelets
What are the lines of Zahn ?
Gross laminations in arterial thrombosis represent pale layers of platelets and fibrin overlapping with darker erythrocytes-rich layers
What is a phlebothrombosis ?
It is venous thrombi typically results from stasis and affect the lower extremities veins more often
What is the fate of the thrombus?
- Propagation: The thrombus may accumulate more platelets and fibrin (propagate), eventually leading to vessel obstruction
- Embolization: Thrombi may dislodge and travel to other sites in the vasculature.
- Dissolution: Thrombi may be removed by fibrinolytic activity
- Organization and recanalization.
- Microbial seeding leading to mycotic aneurysm (RARE)
What does the term Organization and recanalization of the thrombus mean?
replacement of thrombus by connective tissue
- It is penetrated by macrophages, fibroblasts,smooth myocytes and capillaries
- It is gradually dissolved, phagocytized by macrophages and replaced by proliferating connective tissue
- The capillaries which are present in the organized thrombus restores to a limited degree the blood flow
What are the consequences of thrombosis?
- Ischemia by occlusion or narrowing of arterial lumen
- Passive congestion due to the impairment of venous blood outflow without an efficient venous collateral circulation
- Thromboembolism after the detachment of an entire thrombus or its fragments
What is the most common site of DVT ?
What are the clinical manifestations ?
- veins above the knee (e.g., Popliteal, femoral, and iliac veins)
- symptoms (pain, edema, and increased risk of Embolization)
- asymptotic in 50% of the cases being recognized only after Embolization
What is the most common cause of arterial thrombosis?
Atherosclerosis due to abnormal blood flow or endothelial injury