Thrombosis, Embolism and Atheroma Flashcards
what are the complications of atheroma
Stenosis Thrombosis Aneurysm Dissection Embolism Ischaemia
what is arterial stenosis
narrowing of the artery
reduced elasticity
reduced flow in system
tissue ischaemia
what does cardiac ischaemia cause
reduced exercise tolerance angina unstable angina infarct cardiac failure
what is cardiac fibrosis - pathology
loss of cardiac myocytes
replacement by fibrous tissue
loss of contractility
reduced elasticity and filling
what would stenosis of carotid arteries cause
TIA
Stroke
Vascular dementia
what would stenosis of renal arteries cause
hypertension
renal failure
what would stenosis of peripheral arteries cause
claudication
foot/leg ischaemia
what often triggers thrombosis
rupture of atheromatous plaque
when is a AAA ruptured
6cm
what is an arterial dissection
splitting within the media by flowing blood
false lumen filled with blood within the media
what does infarction refer to
ischaemic necrosis (death) of a tissue or organ secondary to occlusion/reduction of the arterial supply or venous drainage
what are the two functions of haemostats and what can disrupt it
1 - maintain blood in a fluid, clot free state
2 - induce rapid, localised haemostatic plug at site of vascular injury
Thrombosis
what is the role of platelets
close small breached in vessel walls
what are the contents of platelets
Alpha granules (adhesion components, e.g. fibrinogen, fibronection, PDGF, anti-heparin, etc. Dense granules (aggregation, ADP)
what happens when turbulence disrupts laminar blood flow
Platelets come into contact with the endothelium
Activated clotting factors are not diluted by the normal rapid flow of blood
Inflow of anticoagulant factors is slowed, allowing thrombi to persist
Activation of endothelial cells is promoted
what does hyper coagulability refer to
alteration in the coagulation pathway which predisposes to thrombosis
what are genetic reasons for a hyper coagulable state
Factor V mutation
Defects in anticoagulant pathways
Defects in fibrinolysis
what are signs of pulmonary infarcts
Wedge-shaped on x-ray
Dyspnoea
Chest pain
Haemoptysis
what do fat embolisms follow
major soft tissue trauma, major bone fractures
what type of embolism is often seen in divers and what is it mechanism
barotrauma
frothy bubbles occlude major vessels
what are the three disease patterns for arteriosclerosis
Atherosclerosis
Monckeberg Medial Calcific Sclerosis
Arteriolosclerosis
what is the most common underlying cause for thrombotic events
atherosclerosis
what are the main targets for atherosclerosis
aorta, coronary arteries, cerebral arteries
what can atherosclerosis cause
PVD - gangrene
Mesenteric artery occlusion - GI ischaemia
Ischaemic encephalopathy - dementia
what is the pathology of atherosclerosis
- Basic lesion is a Plaque
- Raised Focal Lesion of Intima
- Lipid core of cholesterol & esters, lipoproteins
- Fibrous Cap
what happens as plaque size increases
Luminal diameter decreases
Blood flow reduces
Ischaemia results once significant reduction
what happens as the medial structure degrades
weakening of arterial wall
aneurysm development
what are the key stages of atherosclerosis
1 - Chronic endothelial injury 2 - Endothelial dysfunction 3 - Macrophage activation 4 - Lipoprotein oxidation 5 - Foam cell formation, fatty streak 6 - Plaque formation and growth
what is endothelial dysfunction
Increased permeability
Monocyte adhesion
Monocyte emigration
Platelet adhesion
what is the role of lipoprotein oxidation
more easily ingested by macrophages
act as chemotactic factors for monocytes
increase monocyte adhesion
what does lipoprotein oxidation induce/stimulate
stimulate cytokine and growth factor release
induce an antibody response
what are the stages of foam cell formation
Macrophages and smooth muscle cells engulf lipid to become foam cells and form a fatty streak
