Thrombosis and Embolism Flashcards
(28 cards)
What is thrombosis?
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
Abnormalities of flow
- stagnation
- turbulence
Abnormalities of blood components
- smokers
- post-partum
- post-op
What is the appearance of an arterial thrombus?
- Pale
- Granular
- lines of Zahn
- platelets mixed with fibrin
- lower cell content
What is the appearance of venous thrombus?
- Soft
- Gelatinous
- Deep red
- Higher cell content
What are the outcomes of thrombosis?
- Lysis
- Propagation
- Organisation
- Recanalisation
- Embolism
What occurs in lysis of thrombosis?
- complete dissolution of thrombus
- fibrinolytic system active
- blood flow is re-established
- normally occurs when thrombi are small
What occurs in the propagation of a thrombus?
- progressive spread of thrombosis
- occurs distally in arteries
- occurs proximally in veins
What occurs in the organisation of a thrombus?
The thrombus undergoes fibrous repair and forms a fibrous scar on the wall of the vessel.
- ingrowth of fibroblasts and capillaries (similar to granulation tissue)
- lumen remains obstructed
What occurs in the recanalisation of a thrombus?
- blood flow is re-established through reforming channels through the organised thrombus/ occlusion)
- new channels may have smaller capacity than the original vessel
What occurs in the embolism of a thrombus?
- part of the thrombus breaks off
- travels through the bloodstream
- lodges at distant site
What are the effects of arterial thrombosis?
Dependant on the sire and collateral circulation
- ischaemia
- infarction
What are the effects of a venous thrombus?
- congestion
- oedema
- ischaemia
- infarction
What are the most clinical effects of a thrombus?
- Coronary artery thrombosis/ myocardial infarction
- Embolisation resulting in occlusion of an artery distant to the thrombus site
- pulmonary embolism
- cerebral vascular event
- Congestion & oedema in capillary beds
- pain
- skin ulceration
- Thrombosis of uteroplacental vasculature seen in inherited thrombophilias
- repeated miscarriages
What is Virchow’s triad?
Rudolf Virchow was the first to call the process thrombosis and depended on these three things (Virchow’s triad):
- Endothelial damage
- Slow or turbulent flow
- Hypercoagulability
What is an embolism?
A blockage of a blood vessel by a solid, liquid or gas at a site distant from its origin.
- >90% of emboli are thrombo-emboli
What are the types of embolism?
- air
- IV. 100ml of air required for a significant embolus
- cutthroat - froth of air
- amniotic fluid
- common in improper termination of pregnancy
- from rupture of veins in the uterus
- nitrogen
- in joints of divers (the Benz)
- medical equipment
- breakage into fragments
- tumour cells
Where do pulmonary emboli come from?
When a thrombus in the systemic veins passes to small capillaries in the lungs
Where can thrombo-emboli from the left side of the heart travel to?
Through the aorta to renal, mesenteric and other arteries, effectively pass to any part of the body.
Where do thrombo-emboli from the atheromatous carotid arteries travel to?
The brain. Can cause a stroke or a transient ischaemic attack.
Where do atheromatous abdominal aorta thrombus travel to?
Arteries of the legs
What are the predisposing factors to deep vein thrombosis?
- immobility/bed rest
- postoperative
- pregnancy and postpartum
- oral contraceptives
- severe burns
- from dehydration and immobility
- cardiac failure
- disseminated cancer
How can DVT be prevented?
Cannot be ‘prevented’ risk just needs to be reduced
Compression stockings
Flowtron boots
How is DVT treated?
- IV heparin type drugs
- To prevent more thrombus formation, oral warfarin
What are the effects of a massive pulmonary embolism?
- defined as over 60% reduction in blood flow
- rapidly fatal
