| Acute Limb Ischaemia
|
Chronic Critical Limb Ischaemia | Intermittent Claudication
|
|
| Underlying Pathology
|
Gen. due to thromboembolism
Also due to: thrombosis; trauma; other |
Thrombosis superimposed on pre-existing atherosclerosis | Atherosclerotic stenosis |
| Definition
|
Sudden onset of severe ischaemia with assoc. sensory/motor loss and intense pain
|
Persistently recurring rest pain requiring analgesia for ≥ 2 weeks and/or
Ulceration or gangrene of foot/toes and/or Ankle SBP <50mmHg (or toe SBP <30mmHg) |
Pain or fatigue in mm of lower extremity, only brought on by exertion, and always relieved by rest
|
| Symptoms
|
Rest pain, especially with limb elevation
Nocturnal pain Tissue loss: ulceration, gangrene, necrosis |
Reproducible pain, cramping or fatigue in calf, thigh or buttock during exercise
|
|
| Clinical Signs
\ |
Absent peripheral pulses
Tropic changes (hair loss, muscle wasting, clawed toes) Ulceration (punched out, sloughy, necrotic) Gangrene (infection, blistering, abscess, skin breakdown) Necrosis |
Reduced or absent
peripheral pulses
|
|
| DDx
|
Venous ulceration
Malignant skin ulceration Neurogenic related pain
|
Neurogenic claudication (eg nerve root entrapment, spinal canal stenosis)
Venous claudication (history of severe deep vein thrombosis or venous insufficiency) Musculoskeletal causes (eg hip or knee osteoarthritis) |
|
| Ix | Arteriography | Arteriography | Doppler Ultrasonography → Ankle-Brachial Index |
| Rx | SURGICAL EMERGENCY | Need urgent vascular r/v | RF modification = mainstay |
| General/
Medical
|
Anticoagulation – IV heparin
May need anticoagulation RF modification important longer-term |
Analgesia
Management of ulcers – may need antibiotics etc. RF modification |
General measures/RF modification = mainstay of Rx |
| Revascularisation
|
Needed ASAP
Embolectomy Also – catheter directed intra-arterial thrombolysis, endarterectomy, bypass grafting etc.
|
Choice of revascularisation procedure depends on pts, site of obstruction etc.
PCTA Bypass grafting Endarterectomy etc. |
Gen. only indicated only if symptoms are very disabling
Majority of pts never require surgery
|
| Outcomes
|
Post-embolectomy limb salvage rate of 75-85%
30 day mortality – 20-30%
|
60% undergo early vascular reconstruction
20% undergo early 1° amputation Within 12 months, 25% have major amputation, 20% die ∴only 55% alive with both legs intact
|
In 50%, claudication improves/remains unchanged
5% undergo amputation Overall ↓ in LE of 10 years due to co-existing CAD, DM 70% 5-year survival 50% 10-year survival worse prognosis in smokers/diabetics |
- Patients with PAD have a
- 3–4-fold increased risk of acute myocardial infarction (AMI)
- 10–15 times greater risk of cardiovascular mortality
when compared with those without PAD
- At five years, 7% of patients with asymptomatic PAD have clinical deterioration, while 21% of patients with intermittent claudication have a reduction in walking distance or progress to CLTI.
- Long-term amputation rates are highly variable, with a large meta-analysis finding that incidence ranged between 4% and 27%, influenced by other risks such as infection and diabetes-related foot disease
- Classification by clinical presentation
- Asymptomatic (confirmed PAD in an asymptomatic individual)
- Claudication
- Critical limb ischemia
- Acute limb ischemia (ALI)
- The Global Vascular Guidelines recommend the term ‘chronic limb-threatening ischaemia’ (CLTI) replaces the former ‘critical limb ischaemia’.
- This new term seeks to distinguish between acute and chronic ischaemia, and address the increasing contribution of diabetes-related foot disease to limb loss.
- CLTI does not include perfusion parameters as a diagnostic criterion, recognising that amputation risk is often a combination of ischaemia, tissue loss and infection.
Clinical presentation of PAD
- The diagnosis of PAD is often challenging
- Patients may not volunteer symptoms of PAD, and the ‘classical’ presentation of reproducible, exertional leg pain from intermittent claudication is often unrecognised.
- Many patients have their disease ‘masked’ because their walking is already limited as a result of other causes such as
- lumbar degenerative disease
- nerve root compression
- hip and knee osteoarthritis
- frailty syndromes including cognitive impairment.
- Peripheral neuropathy from diabetes may mask painful ulcers or rest pain.
- Mobility limitations due to other causes (sedentary lifestyle, musculoskeletal disease, comorbid illness such as heart failure, COPD)
Screening and diagnosis of PAD
| Sensitivities and specificities of PAD detection methods | ||
| Sensitivity | Specificity | |
| Edinburgh Claudication Questionnaire | 56% | >90% |
| Examination: absence of both pedal pulses | 72% | >90% |
| Examination: femoral bruit | 28% | >90% |
| Ankle-brachial index | 77% | >95% |
| Duplex arterial ultrasound | 96% | >95% |
Ankle Brachial Index Test
- 1.0–1.4 as normal
- 0.9–0.99 as borderline PAD
- <0.9 as diagnostic of PAD
- >1.4 indicates non-compressible arteries
- An abnormal ABI has a high sensitivity/specificity for the presence of PAD.
- ABIs >1.4 indicate incompressibility of the arteries
- arterial calcification
- advanced diabetes, renal insufficiency and in the very elderly
- Measurement of the ABI and arterial waveform analysis using a hand-held Doppler ultrasound device currently attracts a Medicare fee of $63.75 (MBS Item Number 11610) provided a hard copy trace and report are supplied.
- ABI testing can be performed with a hand-held Doppler or automated ABI machine, but most accredited vascular laboratories provide ABI assessment.
Treatment of asymptomatic PAD
- The desired outcome of early detection of PAD is to identify patients at increased risk of cardiovascular events and mortality and to take action to reduce their risk.
- As many PAD patients have involvement of multiple arterial sites and are likely to already be receiving secondary prevention therapies, it has been questioned whether detection of early PAD will significantly alter management.
- However, half of those patients with undiagnosed, asymptomatic PAD have no known cardiovascular disease in other vascular beds
| Secondary prevention of cardiovascular disease | |
| Smoking | Complete cessation |
| Exercise | Moderate level activity (brisk walking) 30 min/day at least 5 days per week |
| Diet | Mediterranean diet: emphasis on fruits, vegetables, healthy oils, nuts/seeds and fish; limit sugar, saturated fats and salt |
| Weight | Target BMI <25 kg/m2; waist measurement <94 cm for men and <80 cm for women; recommend weight loss 5–10% of starting weight or 1–4 kg/month |
| Alcohol | No more than two standard drinks per day for men and women, and no more than four standard drinks on a single occasion |
| Blood pressure | Lifestyle modification ± drug therapy to achieve BP <140/90 mmHg |
| Lipid management | Dietary modification and statin therapy is recommended for all people with clinical evidence of vascular disease. Targets:
LDL-C <2.5 mmol/L HDL-C >1 mmol/L TC <4 mmol/L Triglycerides <1.5 mmol/L |
| Diabetes | HbA1c <7%; fasting blood glucose 4–8 mmol/L |
| Antiplatelet therapy | 75–162 mg/day aspirin is advised for all patients with symptomatic cardiovascular disease |