L10 Haemostasis, thrombosis and embolism Flashcards
Define thrombosis
Thrombosis is the formation of a solid mass formed from the constituents of blood within the circulatory system
What are the components of Virchow’s triad which describes what thrombosis is dependent on. Give an example of how each could occur
1) Changes in the vascular wall (endothelial damage) - atheroma/direct injury/ inflammation
2) Changes in blood flow - slow or turbulent flow
3) Changes in blood components (hypercoagulability) - smokers/ post-partum/post-op
We can identify arterial from venous thrombi by their apearance. Describe some differences between them/
Arterial - pale, granular, clear lines of Zahn present, lower cell content
Venous - soft, gelatinous, deep red, higher cell content
Give four of the five possible outcomes of thrombosis
lysis (resolution)/propagation/organisation/recanalisation/embolism
Propagation refers to the progressive spread growth of said thrombus. Does it spread distally or proximally in a) arteries b) veins
a) distally
b) proximally
What is organisation?
When the thrombus undergoes fibrous repair and forms a small scar on the vessel wall so lumen is still partially obstructed
What is recanalisation?
think ‘canal’ - Thrombus is partially dissolved - smaller channels run through occluding thrombus so bloodflow is re-established but not to it’s original capacity
What is an embolism?
the blockage of a blood vessel by solid, liquid or gas at a site distant to it’s origin (part of the thrombus breaks off and travels too a new site often causing more major problems)
Give some clinical effects of thrombosis
Ischaemia/infarction/congestion and oedema in venous circulation which can cause pain and ulceration/ miscarriage due to blockages in the uterine vasculature/embolisation to another site
Over 90% of embolisms are thrombo-embolisms, what other types of embolism can occur?
-air/amniotic fluid/nitrogen/medical equipment/tumour cells
Give some common locations of emobli and where they originally come from
Pulmonary emboli - from systemic circulation
Renal/mesenteric etc. emboli - from the heart
Brain - from carotid arteries
Legs - from abdominal aorta
Give three predisposing factors to deep vein thrombosis
immobility/bed rest Post-operative pregnancy and post-partum severe burns cardiac failure
What prophylaxis is given to people identified at high risk of DVT (remember prophylaxis simply means treatment for or to prevent a disease)
Heparin (anticoagulant)
Leg compression during surgery (Flowtron boots)
note - treatment aims to prevent further propagation to bigger arteries where thrombus can become a bigger problem rather than to actually get rid of the thrombus most of the time
A ‘massive’ PE is considered as greater than a 60% reduction lung blood flow this can be rapidly fatal, why can small PE’s be so worrying?
Because they are often asymptomatic and overtime can lead to pulmonary hypertension
What are the general treatments and preventions for thromboembolic disease
anticoagulants such as heparin/patients encouraged to mobilise as soon as possible/ immobilised lower limbs elevated to ensure venous return/aspirin - inactivates an enzyme in the amplification of platelet aggregation/ warfarin/ filters for pulmonary emboli
