Vessels of the Lower Limb Flashcards
Why is the femoral artery vulnerable to injury/laceration?
it is positioned superficially in the femoral triangle
What is the clinical importance of the femoral artery?
it can be easily accessed in most people:
- to obtain ABG (arterial blood gas) in emergencies if there is poor peripheral perfusion/pulses
- to undertake minimally invasive procedures
What are the borders of the femoral triangle and the vessels that pass through it?
How is the femoral artery used as an important access point?
a catheter can be placed into the femoral artery which can then be advanced up the arterial tree to the target organ
this provides minimally invasive access to perform procedures including:
- coronary angiography
- coronary angioplasty
- embolisation of berry aneurysms
Why might the femoral vein be used in an emergency?
it is used for emergency IV access temporarily in:
- trauma
- burns
- otherwise very difficult access - (VDU, thrombosed peripheral veins, obesity)
It can also be used for venepuncture and VBG in emergencies
When is the great saphenous vein used clinically?
Where is it positioned?
it lies immediately in front of the medial malleolus
it can be used in emergencies to obtain IV access
What is meant by vascular disease of the lower limb?
it is a disease of the lower limb arteries
What is lower limb ischaemia most commonly caused by?
atherosclerotic disease
What is meant by ischaemia?
when perfusion fails to meet the demands of tissues
tissue hypoxia and anaerobic metabolism result
this leads to tissue damage and death is adequate perfusion is not restored
What is the difference between chronic and acute ischaemia?
chronic ischaemia:
a gradual process caused by atherosclerosis
acute ischaemia:
a sudden loss of perfusion of the the limb
it is usually the result of an occlusive thrombus or embolus in an artery, but can also occur secondary to trauma
What is the disease process behind atherosclerosis?
What happens if the plaque remains stable or ruptures?
lipids are deposited in lesions in the walls of large arteries
plaques may remain stable and partially occlude the artery to cause symptoms
if inflammation continues in a plaque, they become unstable and rupture
What happens when an atherosclerotic plaque ruptures?
the contents of the core are exposed to blood
the core is highly thrombogenic
this leads to platelet aggregation and the activation of the coagulation cascade
After rupture of an atherosclerotic plaque, what 2 types of thrombus may form?
- a thrombus that stays where it is but occludes the vessel lumen
- a thrombus that breaks away from the vessel wall (embolus) and travels downstream to lodge or occlude a smaller vessel
They both lead to an ischaemic event
Where does atherosclerosis tend to happen?
It affects large and medium conduit arteries
It occurs due to turbulence of blood flow at bifurcation points
It commonly affects the coronary, carotid and lower limb arteries as well as the aorta
What are the 4 levels in the Fontaine Classification of limb ischaemia?
- asymptomatic
- intermittent claudication
- ischaemic rest pain
- ulceration/gangrene (= critical ischaemia)
What happens during the early stages of chronic lower limb ischaemia?
it is a gradual process so is asymptomatic for some time
the plaques grow and blood flow is increasingly obstructed, but there is time for collateral circulation to develop
at first occlusion is only noticeable when the patient is active
What happens as chronic lower limb ischaemia develops and the patient becomes more symptomatic?
perfusion cannot meet the oxygen demands of the limb muscle, leading to anaerobic metabolism in muscle cells
this is ischaemia and causes pain - intermittent claudication
initially, the pain is relieved with rest
What are the 2 main signs of critical ischaemia as a result of chronic lower limb ischaemia?
- pain at rest
- ulceration and gangrene
patients may not present until they have ulceration/gangrene
