Thrombosis And Embolism Flashcards
What is thrombosis?
The formation of a solid mass of blood within the circulatory system
(Not a clot)
Why does thrombosis occur?
-abnormalities of the blood vessels due to
Atheroma/direct injury(not a cut)/inflammation
- abnormalities in blood components due to smokers(hyper-coagualable blood)/post-partum (natural thickens/makes blood sticker)/ post-op (physiological change and lying in a bed-stagnation)
- abnormalities of blood flow due to stagnation/turbulence
What does an arterial thrombus look like?
- pale (paler than venous due to less cellular content)
- granular
- lines of Zahn (layered look- different amounts of RBC- paler and darker lines)
- lower cell content
What does a venous thrombus look like?
- softer
- gelatinous
- deep red (more RBCs)
- higher cell content
What are the outcomes of thrombosis?
- lysis (best outcome)
- propagation (enlargement)
- organisation
- recanalisation
- embolism
What is lysis?
Outcome of thrombosis
- complete dissolution of thrombus
- fibrinolytic system active
- blood flow re-established
- most likely when thrombin are small
What is propagation?
Outcome of thrombosis
- progressive spread of thrombosis
- distally in arteries (away from the heart)
- proximal in veins (towards the heart) - thrombus gets larger and thicker because it is forming in larger vessels
What is organisation (in terms of an outcome of thrombosis)?
- reparative process
- ingrowth of fibroblast and capillaries growing in and replacing the thrombus itself (similar to granulation tissue)
- lumen remains obstructed (no flow restored)
What is recanalisation?
Outcome of thrombosis
- blood flow re-established but usually incompletely
- one or more channels formed through organising thrombus (smaller and likely to get turbulent flow within the new channels- further thrombosis?)
What is embolism?
Outcome of thrombosis
- part of thrombus breaks off
- travels through bloodstream
- lodges at distant site
What are the effects of an arterial thrombosis?
- ischemia (block arteries)
- infarction (if there is an end artery), depend on site and collateral circulation (not always)
What are the effects of venous thrombosis?
- congestion
- oedema (hydrostatic pressure)
- ischaemia (occasionally) pressure in vessels increases until it equals that of the hydrostatic pressure within vessels and there is no movement in nor out of the vessels and in this way no oxygen is transported to tissues
- infraction (occasionally)
What is an embolism?
The blockages of a blood vessel by solid, liquid or gas at a site distant from its origin
> 90% of emboli are thrombo-emboli
Name some types of embolisms?
Thrombo
Air- makes blood frothy
Amniotic fluid
Nitrogen- N2 formed in the blood, decompression (divers resurfacing too quickly)
Medical equipment- broken off
Tumour cells- larger lumps break off and can cause ischaemia
Septic emboli- infection on heart valves ie can break off
Discuss thrombo-embolis:
1) Where do they end up if the thrombosis was in the vein?
2) What happens to an embolism if you have thrombus in the heart?
3) What happens if you have an atheromatous carotid artery?
4) What happens if you have atheromatous in the abdominal aorta?
1) Pass into lungs= pulmonary embolism (nearly always)
2) Pass via the aorta to absolutely anywhere in the body ie renal, mesenteric arteries
3) Emboli can pass to brain
4) Emboli can pass to arteries of the legs
