Thrombosis And Embolism Flashcards
Define thrombosis
Thrombosis is the formation of a solid mass of blood within the circulatory system
Why does thrombosis occur?
Abnormalities of the vessel wall: atheroma, direct injury, inflammation (e.g. vasculitis)
Abnormalities of blood flow: stagnation, turbulence
Abnormalities of blood components: smokers post-partum (after baby), post-op.
What do arterial thrombi look like?
pale, granular, lines of Zahn, lower cell content
What do venous thrombi look like?
Soft, Gelatinous, Deep red as higher cell content
What are the outcomes of thrombosis?
Lysis
Propagation
Organisation
Recanalisation
Embolism
Lysis of thrombus?
Complete dissolution of thrombus
Fibrinolytic system active
Bloodflow re-established
Most likely when thrombi are small
Propagation of thrombosis?
Progressive spread (enlargement) of thrombosis
Distally in arteries (away from heart) and proximally in vein (towardsthe heart) because of direction of blood flow.
Organisation of thrombosis?
Reparative process
Ingrowth of fibroblasts ad capillaries (similar to granulation tissue)
Lumen remains obstructed
Recanalisation of thrombosis?
Bloodflow is partially reestablished.
One or more channels formed through organising thrombus.
Embolism of thrombosis?
Part of thrombus breaks off
Travels through the bloodstream
Lodges at distant site
What are the effects fo arterial thrombosis?
Ischaemia
Infarction (if end arteries but not if collateral circulation)
Depends on site and collateral circulation
What are the effects of venous thrombosis?
Congestion (usually more than one way for blood to get back to heart but it slowed down).
Oedema
Ischaemia - when tissue pressure = venous pressure
Infarction
But, most not cause ischemia / infaction because of collateral circulation.
Define embolism
Embolism is the blockage of a blood vessel by solid, liquid or gas at a site distant from its origin.
>90% of emboli are thrombo-emboli
What are other types of emboli?
Air - from IV injections/ infusions (need 100ml to cause air embolus)
Amniotic fluid
Nitrogen - divers if not decompression appropriately
Medical Equipment - go into arteries instead of veins
Tumour Cells
Where could the thrombus occur in thrombo-emboli?
From systemic veins to the lungs = pulmonary emboli
From the heart pass via the aorta to renal, mesenteric and other arteries
From atheromatous carotid arteries pass to the brain Fro atheromatous carotid arteries pass to the brain - can cause mini stroke.
From atheromatous abdominal aorta pass to arteries of the leg
What are the predisposing factors for DVT?
Immobility / bed rest
Postoperative
Pregnancy and post-partum
Oral contraceptives
Cardiac failure
Severe burns
Disseminated cancer
Can DVT be prevented?
Can reduce risk fo DVT rather than prevention.
- Heparrin to interfere with coagulation
- Compressing leg veins using TED stockings
- Flowtron boots during surgery
- Movement - bending legs
Can DVT be treated?
Intravenous heparin type drugs
Oral warfarin
- not dissolve thrombus but prevent significant propagation.
What are the effects of pulmonary embolism?
Massive PE >60% reduction in blood flow - rapidly fatal
Major PE - medium sized vessels blocked Patient short of breath +/- cough and blood stained sputum
Minor PE - small peripheral arteries blocked. Asymptomatic or minor shortness of breath
Recurrent minor PEs lead to pulmonary hypertension.
Where else can embolisms occur?
Cerebral embolism
Iatrogenic embolism (caused by air during medical examination)
Fat embolism
