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
What is an embolism?
Any intravascular solid, liquid or gaseous masses carried by blood from its origin to a distant site and 99% arise from thrombus
What is the main cause of pulmonary embolism?
95% caused by DVT
What area the characteristics and consequences of pulmonary embolism (PE) ?
- 60% to 80% are small and clinically silent
- sudden death or right-sided heart failure may occur if 60% or more of pulmonary circulation is obstructed with an emboli
- multiple emboli may cause pulmonary hypertension and right-sided heart failure over time
- PE in medium-size arteries may cause pulmonary hemorrhage or infarction
What is the most common cause of systemic thromboembolism? And what are other causes?
80% arise from Intracardiac mural thrombi
- two thirds or at least 55% associated with MI
- 25% associated with atrial fibrillation
- around 15% associated with aneurysms and atherosclerosis
What is the major site of arteriolar Embolization?
- 75% lower extremities
- 10% brain
What is fat pulmonary bone marrow embolism ?
- Pulmonary embolization of Microscopic fat globules as a result of fractures of long bones(which have fatty marrow) and rarely from soft tissue trauma and burns.
- fewer than 10% have any clinical findings
What are the clinical manifestations of fat embolism syndrome?
pulmonary insufficiency, diffuse rash, neurologic symptoms, anemia, and thrombocytopenia.
What is an infarction?
Necrosis of a particular tissue caused by occlusion of either arterial supply or venous drainage.
What are the subdivisions of the infarction?
- ischaemic (white)
• in solid organs (e.g., heart, kidneys, and spleen) - hemorrhagic (red)
• in venous occlusion (e.g., ovaries and testes)
• in loose tissues (e.g., lungs)
• in tissues with dual circulations (e.g., small intestines)
• in previously congested tissues
What is the characteristic sign in Histological examination of an infarction?
- coagulative necrosis followed by inflammatory response
What is the fate of an infarction?
- Infarcts ultimately replaced by scar tissue
- depending on the tissue, parenchymal regeneration may occur
What are the phases representing nuclear damage in infarction?
- pyknosis – nuclei are shrunken and more intensively stained with hematoxylin
- karyorhexis – nuclei undergo fragmentation
- karyolysis – nuclei lose ability to stain with hematoxilin and eventually disappear
What does the term „haemorrhagic infarct of lung” designate?
local necrosis of lung tissue (interalveolar septa) accompanied by massive haemorrhage within pulmonary parenchyma
What is the most common cause of hemorrhagic infarct of lung?
embolic occlusion of a peripheral branch of pulmonary artery in case of left-sided heart failure “left ventricle insufficiency” as a result of bronchial circulation failure to sustain the pulmonary parenchyma
What does the term post-embolic focus mean?
extravasations into alveolar spaces identical grossly with haemorrhagic infarct caused by an embolism In normal cardiovascular condition
