Session 5-Haemostasis, Thrombosis And Embolism Flashcards
Define thrombosis
Formation of solid mass of blood within circulatory system
Why does thrombosis occur? (3)
1) abnormalities of vessel wall
2) abnormalities of blood flow
3) abnormalities of blood components
What vessel wall abnormalities can lead to thrombosis?
Atheroma (more important in arterial, not venous, thrombosis)
Direct injury
Inflammation
What blood flow abnormalities can lead to thrombosis?
Stagnation
Turbulence
Describe the appearance of arterial thrombi (4)
1) pale
2) granular
3) lines of Zahn
4) lower cell content
Describe the appearance of venous thrombi (4)
1) soft
2) gelatinous
3) deep red
4) higher cell content
Why are arterial thrombi paler than venous thrombi?
RBC content is lower in arterial thrombi
What are the outcomes of thrombosis? (5)
1) Lysis
2) Propagation
3) Organisation
4) Recanalisation
5) Embolism
What happens in lysis?
1) Complete dissolution of thrombus
2) Fibrinolytic system is active
3) Blood flow is re-established
When is lysis most likely?
When thrombi are small
What happens in propagation?
Progressive spread and enlargement of thrombosis
In which direction do thrombi propagate in:
1) arteries
2) veins?
1) dismally
2) proximally
True or false: turbulence causes more thrombi to form
TRUE
What happens in organisation of thrombosis?
Ingrowth of fibroblasts and capillaries (replace the thrombus)
Lumen remains obstructed
What happens in recanalisation?
Blood flow is re-established but usually incompletely
One or more channels formed through organising thrombus
What happens in embolism?
Part of thrombus breaks off and travels through blood stream and lodges at distant site
What are the effects of arterial thrombus?
Ischaemia
Infarction
What are the effects of venous thrombus?
Congestion
Oedema
Ischaemia
Infarction
Define embolism
Blockage of blood vessel by solid, liquid or gas at site distant from its origin
What are 90% of emboli?
Thrombo-emboli
What are other types of embolism?
Air Amniotic fluid Nitrogen Medical equipment Tumour cells Septic emboli
What is pulmonary emboli?
From systemic veins to lungs
What are the predisposing factors of deep vein thrombosis? (7)
1) immobility/bed rest
2) post-op
3) pregnancy
4) oral contraceptives
5) severe burns
6) cardiac failure
7) disseminated cancer
What are flowtron boots?
Inflate and mimic muscle pump of calf to assist venous return
How can DVT be treated?
1) intravenous heparin type drugs (prevents propagation)
2) oral warfarin (anticoagulant)
What happens in a massive pulmonary embolism?
> 60% reduction in blood flow is rapidly fatal
What happens in a major pulmonary embolism?
Medium sized vessels blocked
Patients are short of breath
Cough and blood stained sputum
What happens in a minor pulmonary embolism?
Small peripheral pulmonary arteries blocked
Asymptomatic or minor shortness of breath
What do recurrent minor pulmonary embolisms lead to?
Pulmonary hypertension
When does fat embolism occur?
When long bone fractures, fracture leads to release of bone and marrow which enters blood stream and can enter brain
