Key Facts

PAD is a marker of systemic atherosclerosis. Management focuses on cardiovascular risk reduction and limb-specific treatment.

Epidemiology

Prevalence ~5-10% of adults >50 years; increases to ~15-20% in >70 years. Only ~25% of PAD patients are symptomatic. ~100,000 people have CLI in the UK.

Aetiology

• Atherosclerosis is the cause in >95% of cases
• Risk factors: Smoking (strongest — 4× risk), diabetes, hypertension, hyperlipidaemia, age, male sex, CKD, family history
• Other causes: Buerger's disease (thromboangiitis obliterans — young male smokers), popliteal entrapment, fibromuscular dysplasia

Pathophysiology

• Atherosclerotic plaque narrows arterial lumen → reduced blood flow → ischaemia
• Claudication: Supply-demand mismatch during exercise → muscle ischaemia → pain
• CLI: Insufficient perfusion at rest → rest pain (worse at night, improved by hanging leg down — gravity-dependent), tissue loss
• Common sites: Superficial femoral artery (most common), iliac arteries, tibial arteries (especially in diabetics)

Intermittent Claudication (Fontaine II)

• Cramping pain in calf (SFA disease), thigh (iliac disease), or buttock (aortoiliac) on walking
• Consistent claudication distance
• Relieved within minutes of rest
• No pain at rest

Leriche Syndrome (Aortoiliac Occlusion)

• Buttock/thigh claudication + absent femoral pulses + erectile dysfunction

Critical Limb Ischaemia (Fontaine III-IV)

• Rest pain: Severe, usually forefoot; worse at night; relieved by dependency (hanging foot over bed)
• Tissue loss: Ulceration (typically painful, punched-out, distal) or gangrene
• 6 Ps: Pain, Pallor, Pulselessness, Perishing cold, Paraesthesia, Paralysis (acute ischaemia)

Acute Limb Ischaemia

• Sudden onset of the 6 Ps
• Causes: Embolism (AF, mural thrombus), thrombosis in situ, graft occlusion
• Surgical/interventional EMERGENCY — limb has ~6 hours before irreversible damage

Red Flags

• Rest pain — CLI, urgent referral
• Tissue loss (ulceration/gangrene) — limb-threatening
• Acute onset 6 Ps — emergency, consider embolectomy

Bedside

• ABPI: <0.9 = PAD; 0.5-0.9 = moderate; <0.5 = severe/CLI; >1.3 = calcified (unreliable)
• Pulse examination: Femoral, popliteal, dorsalis pedis, posterior tibial
• Buerger's test: Limb elevation → pallor; dependency → reactive hyperaemia (rubor)
• Handheld Doppler: Assess arterial signals

Bloods

• FBC, U&Es, HbA1c, lipids: Cardiovascular risk assessment
• Coagulation: If revascularisation planned

Imaging

• Duplex ultrasound: First-line — non-invasive, identifies stenosis/occlusion
• CT angiography: Pre-operative planning for revascularisation
• MR angiography: Alternative to CTA (avoids contrast nephropathy risk)
• Digital subtraction angiography (DSA): Gold standard (but invasive); used during endovascular intervention

Conservative (First-Line for Claudication)

• Supervised exercise programme: 2 hours/week for ≥3 months (NICE CG147) — improves walking distance by ~100-200%
• Smoking cessation: Most important modifiable intervention
• Statin: Atorvastatin 80mg OD (regardless of lipid levels)
• Antiplatelet: Clopidogrel 75mg OD (preferred over aspirin — CAPRIE trial)
• Antihypertensive: Target <140/90 (or <130/80 if diabetic)
• Diabetes optimisation: HbA1c target
• Foot care: Chiropody, appropriate footwear (especially diabetics)

Revascularisation (CLI or Lifestyle-Limiting Claudication Failing Conservative)

Endovascular (angioplasty ± stenting):

• First-line for short-segment stenosis/occlusion
• Iliac angioplasty has best long-term patency (~70-80% at 5 years)

Surgical bypass:

• Autologous vein graft (long saphenous) preferred — better patency than synthetic
• Femoral-popliteal bypass; femoral-tibial bypass for distal disease
• Consider for long-segment occlusion or failed endovascular

Amputation:

• If revascularisation not possible and CLI/unreconstructable — below-knee (BKA) preferred over above-knee (AKA)
• Rehabilitation with prosthesis

Referral Criteria

• CLI (rest pain, tissue loss) — urgent vascular referral (within 24 hours for tissue loss)
• Acute limb ischaemia — emergency vascular surgery
• Lifestyle-limiting claudication despite 3 months supervised exercise — vascular referral

• Claudication: ~75% remain stable or improve with exercise; ~25% worsen; ~5% proceed to CLI over 5 years
• CLI: 1-year mortality ~25%; 1-year amputation rate ~30%
• Cardiovascular mortality: PAD patients have ~3× increased risk of MI, stroke, CV death
• 5-year mortality: ~20% for claudicants; ~50% for CLI patients (from cardiovascular events)
• Post-bypass patency: Vein graft ~70-80% at 5 years; synthetic ~50-60% at 5 years
• Post-amputation: 30-day mortality ~10-15% (major amputation); 50% mortality at 2 years

Fontaine Classification

ABPI Interpretation