Flashcards in Arterial Disease and Aneurysms Deck (42):
List some causes of arterial occlusion
Embolism (cardiac, arterial to arterial)
Low flow state
Ischaemic pain in exercising muscles due to imbalance between workload of muscles and ability to maintain aerobic metabolism (angina of the legs)
Describe the pathophysiology of claudication
Posterior calf muscles dominate with walking
When flow of oxygenated blood is inadequate, muscles switch to anaerobic metabolism to meet energy demands
Lactic acid builds up and produces aching discomfort
Eases with rest
What are the clinical criteria for claudication?
Calf pain on exertion (+/- thigh, +/- buttock)
Onset and severity related to workload
Relieved with rest
Where does ischaemic rest pain occur?
Most distal part of the limb
Describe the pathophysiology of ischaemic rest pain
Inadequate perfusion resulting in anaerobic metabolism in skin and nerves (cf muscles) of the extremity
How is ischaemic rest pain defined clinically?
Burning pain in extremity at rest (often wakes patient in the night)
Usually relieved with gravity
What are the features of critical limb ischaemia (CLI)?
Ischaemic rest pain
At what ankle and toe pressure does rest pain occur?
At what ankle and toe pressure do ulcers/gangrene occur?
What is the trans-cutaneous O2 pressure in CLI?
What are some possible patterns of lower limb occlusive disease?
What are the features of aorto-iliac occlusive disease?
Calf, thigh and buttock claudication
Reduced pulses femoral and below
May be bruits over aorta/iliac
What are the features of femoro-popliteal occlusive disease?
Reasonable femoral pulse but weak or absent popliteal and pedal pulses
Bruit along line of femoral or popliteal arteries
What are the features of tibial/crural occlusive disease?
May be no claudication
Reasonable popliteal pulses but absent pedal pulses
Bruits over popliteal or upper tibial arteries
Describe the epidemiology of peripheral arterial disease
12% of adult population and 20% of population >70 years
Associated with 6-fold increase in CV mortality (patients at high risk need aggressive risk-factor modification and antiplatelet drugs)
Management options for claudication
Angioplasty +/- stenting
When are angioplasty, endarterectomy and bypass indicated?
Angioplasty: best for short segments, better in proximal arteries
Endarterectomy: short segments
Bypass: longer blocks
What are the risks with endovascular interventions?
Chance of access vessel problems
Chance of thrombosis or embolisation
What are the risks with open bypass?
Describe the recovery from endovascular procedures vs open bypass
Endovascular procedures: quick recovery
Open bypass: 2-3 months or longer before back to normal comfort, mobility, etc
What is the typical cause of sudden/severe ischaemia?
What are the clinical features of sudden/severe ischaemia?
Pain (especially on using muscles; later pain in extremities lessens as nerve function decreases)
Paralysis of muscles (especially weakness of anterior compartment muscles)
What is an aneurysm?
Degenerative focal arterial dilatation 1.25-1.5x greater in diameter than adjacent normal artery
Describe the pathogenesis and natural history of aneurysms
Weakness in elastin and collagen in adventia and media results in local inflammation with matric proteins and metallo-proteinases, leading to focal arterial dilatation
Abnormal wall becomes lined with thrombus
Natural history is continued expansion leading to eventual rupture
List common sites for aneurysm
Abdominal aorta (infra-renal)
Describe the risk of aneurysm rupture as related to diameter
Uncommon 6cm annual risk is 9%
>8cm annual risk is 25%
What is the 5-year survival of patients with aneurysm >5cm who are not operated on?
Describe primary prevention for aneurysm
Describe secondary prevention for aneurysm rupture
Screening and treatment of aneurysms >5-5.5cm
What is the average increase in the size of small aneurysms annually?
What is the margin of error for U/S measurement of aneurysms?
Minimum +/- 2mm
Commonly +/- 4mm
How does ruptured AAA present clinically?
Sudden onset abdominal and/or back pain
What is the typical demographic affected by ruptured AAA?
What are the clinical signs of ruptured AAA?
Pulsatile mass in lower abdomen (usually to one side and into iliac fossa)
Features of progressive hypovolaemia
What are the management options for ruptured AAA?
Prompt repair (open or endoluminal)
When should "no intervention" be considered for a ruptured AAA?
Already unconscious/intubated on arrival (especially >80 years)
Already turned down for elective repair in view of co-morbidities
Maximum time of surveillance before EVAR indicated?
3.0-3.9cm: 24 months
4.0-4.6cm: 12 months
4.7-5.0cm: 6 months
5.1-5.5cm: 3 months
What is the 5-year prognosis for patients with local vs systemic claudication?
Local: 5% require intervention, 2% amputation
Systemic: 30% die, 5-10% suffer non-fatal CV events
What is the management philosophy underlying claudication?
Reasonable distance claudication is benign (limb not in jeopardy)
Any intervention on an artery is a "controlled injury"; it may or may not work, there may be complications, and it may not be durable
When is an intervention for claudication reasonable?
If it is a very significant handicap, the risk is acceptable and the proposed intervention has an acceptable chance of working
Patient has to be pushing for an intervention; requires good information and realistic expectations