Peripheral vascular disease (acute and chronic limb ischaemia) Flashcards
What are the three patterns of presentation of PAD?
Three main patterns of presentation may be seen in patients with peripheral arterial disease:
- intermittent claudication
- critical limb ischaemia
- acute limb-threatening ischaemia
What is the classification for PAD?
Fontaine classification:
- Asymptomatic
- Intermittent claudication
- Ischaemic rest pain
- Ulceration/gangrene (critical ischaemia)
What is the definition of claudication?
Inadequate blood flow during exercise, causing fatigue, discomfort, or pain.
What is the definition of critical limb ischaemia?
Compromise of blood flow to an extremity, causing limb pain at rest. Patients can develop ulcers or gangrene.
What is the definition of acute limb ischaemia?
A sudden decrease in limb perfusion that threatens limb viability. Associated with the “6 Ps”: pain, paralysis, paraesthesias, pulselessness, pallor, and poikilothermia.
How common is PAD?
Increases with age
40-49yrs - 1%
50-59yrs - ~4%
60-69yrs- 5%
What are the most common causes of acute limb ischaemia?
- Thrombosis - 40%
- Emboli - 38%
- Graft/angioplasty occlusion - 15%
- Trauma
- Arterial tumour
- Arterial dissection
- Vasospasm
- Takayasu’s
- Temporal arteritis
- Thoracic outlet obstruction
- Buerger’s disease
What are the 6 features of acute limb ischaemia?
Features - 1 or more of the 6 P’s
- pale
- pulseless
- painful
- paralysed
- paraesthetic
- ‘perishing with cold’
Pain and numbness occur first because nerves are most sensitive to ischaemia. Lower limb can survive for up tp 6-8 hours before injury becomes irreversible.
What are the feaures of claudication?
- aching or burning in the leg muscles following walking
- patients can typically walk for a predictable distance before the symptoms start
- usually relieved within minutes of stopping
- not present at rest
Name some features of Leriche’s syndrome.
Buttock claudication and impotence
What vascular disease are young heavy smokers at risk of?
Buerger’s disease - thromboangiitis obliterans (non atherosclerotic smoking related inflammation and thrombosis of veins and medium sized arteries causing thrombophlebitis and ischaemia (–>ulcers, gangrene)
What does buttock claudication as opposed to calf claudication suggest?
Buttock - iliac disease
Calf - femoral disease
What are the differentials for peripheral arterial disease?
- Spinal claudication (but all pulses are present)
- Osteoarthritis of the hip/knee (knee pain often at rest)
- Peripheral neuropathy (associated with numbness and tingling)
- Popliteal artery entrapment (young with normal pulses)
- Venous claudication (bursting pain on walking with previous DVT)
- Fibromuscular dysplasia
- Buerger’s disease (young males, heavy smokers)
What tests should you do if you suspect PAD?
- ABPI & exercise treadmill testing - see if ABPI falls by >0.2 after the exercise (i.e.worse). Exercise component improves the sensitivity of the test.
- Duplex ultrasound + doppler - decreased pulsatility between proximal and distal sites, peak systolic velocity >2.0
- Catheter angiogram/CTA/MRA - anatomical detail of stenosis or occlusions
- Bloods - FBC (plt), PT/PTT, creatinine, lipids, thrombophilia screen, homocysteine levels
What is the ABPI in critical limb ischaemia?
An ankle-brachial pressure index (ABPI) of < 0.5 is suggestive of critical limb ischaemia.
How do you interpret ABPI?
- Normal = 1.0-1.2
- PAD = 0.5-0.9
- Critical limb ischaemia = <0.5 or ankle systolic pressure <50mmHg
What are the 3 L’s to consider when assessing severity of PAD?
Life - does it threaten life or will the intervention do so?
Limb - will the patient lose the limb?
Lifestyle - is the lifestyle of pt severely handicapped? Does it require intervention?
What is the management of claudication?
- Risk factor modification - quit smoking, treat HTN, statin + antiplatelet for all (aspirin or clopidogrel)
- Supervised exercise programme - 3 times a week for 45mins for 3 months; improves collateral blood flow. Encourage patients to exercise to the point of maximal pain.
- Symptom relief -e.g. naftidrofuryl (or cilostazol) but only when patient does not want revascularisation and when exercise offers little benefit.
Name 2 drugs which can be used to treat PAD.
Naftidrofuryl - vasodilator that inhibits vascular and platelet 5-hydroxytryptamine2 (5-HT2) receptors to reduce lactic acid levels. At dose of 1-200mg TDS it may increase walking distance and improve QoL.
Cilostazol - phosphodiesterase III inhibitor with both antiplatelet and vasodilator effects - not as effective as the above.
What is the management of critical limb ischaemia?
Urgent referral to vascular surgeon for revascularisation - risk stratification is done according to the WiFi score
Surgery
If not suitable for surgical revascularisation:
- Amputation
- Spinal cord stimulation
How do you manage acute limb ischaemia?
Urgent referral to vascular surgeons for assessment
Ankle brachial index or duplex ultrasound
Anticoagulation
Paracetamol +/- opioid
Non-viable limb: amputation
Viable limb: revascularisation by:
- percutaneous catheter-directed thrombolytic therapy
- percutaneous mechanical thrombus extraction (Fogarty catheter)
- surgical thrombectomy
- bypass +/- arterial repair
What are the surgical options for PAD?
Percutaneous endovascular revascularization - angioplasty +/- stent or balloon placement, used only for short segment stenosis (<10cm), aortic iliac disease
Surgical revascularization- bypass graft in extensive disease. Can be femoral-popliteal, femoral-femoral crossover, and aorto-bifemoral bypass grafts. Autologous vein > prosthetic (Dacron or PTFE) when knee joint is crossed.
Amputation - <3% with claudication require this within 5 years. Can relieve pain and death from sepsis/gangrene.
Why should the knee be preserved in amputation? What drug is used to prevent phantom limb syndrome?
Improves mobility and rehabilitation potential (must be balanced with the need to ensure wound healing)
Rehabilitation should be started early with a view to limb fitting
Gabapentin is used to treat gruelling complication of phantom limb.
What are the complications of PAD?
Leg/foot ulcers
Gangrene
Permanent limb weakness/numbness
Permanent limb pain - occurs in non-viable limb
What is the prognosis in PAD?
ABI is a marker for cardiovascular events beyond the diagnosis of PAD
Claudication - remains stable and does not worsen quickly
Critical limb ischaemia - at 1yr 1in4 will die and 30% will have amputation
Acute limb ischaemia - depends on completeness of revascularisation
Summarise compartment syndrome.
After acute limb ischaemia, revascularisation can cause reperfusion injury and release of toxic metabolites into the bloodstream. In muscle compartments, consequent oedema may lead to compartment syndrome.
This requires fasciotomies - release of fascia to prevent muscle damage.
Name a cause of acute upper limb ischaemia.
Usually emboli secondary to compression with a cervical rib/band
Where is it more common for an embolus to lodge in the upper limb?
50% lodge in BRACHIAL artery
30% in AXILLARY artery
Sources: left atrium with cardiac arrhythmia (which may also present with impaired consciousness), mural thrombus
What is the pattern of colour change in Raynaud’s? How is it treated?
White –> blue –> red
Calcium antagonists - e.g. nifedipine
Lecture:
What are the three main diagnostic features of critical limb ischaemia?
- Rest pain or tissue loss
- >2 weeks duration (otherwise acute ischaemia)
- Ankle pressure <40mmHg
What is the new name for critical limb ischaemia?
Chronic limb threatening ischaemia
