Key Facts

Peripheral arterial disease (PAD) is the manifestation of atherosclerosis in the arteries supplying the lower limbs. It ranges from asymptomatic disease to intermittent claudication and critical limb ischaemia.

Epidemiology

• Affects ~13% of people >50 years; prevalence increases with age
• Only ~25% of PAD patients are symptomatic
• Male:female ratio ~2:1
• UK prevalence: ~20% of people >60 years have some evidence of PAD on ABPI

Aetiology

• Atherosclerosis — identical process to coronary and cerebral artery disease
• Risk factors: smoking (OR ~3-5), diabetes, hypertension, hyperlipidaemia, CKD, family history, age, male sex
• Non-atherosclerotic: Buerger disease (thromboangiitis obliterans — young male smokers), popliteal entrapment, fibromuscular dysplasia

Pathophysiology

• Atherosclerotic plaque formation → progressive stenosis of peripheral arteries
• Most commonly affected: superficial femoral artery (most common), iliac, popliteal, tibial arteries
• Stenosis → inadequate blood flow to meet metabolic demands during exercise → claudication
• Critical limb ischaemia: rest perfusion is inadequate → ischaemic rest pain, ulceration, gangrene
• Collateral circulation may develop and partially compensate

Intermittent Claudication

• Cramping pain in calf (most common), thigh, or buttock on walking
• Consistent 'claudication distance'
• Relieved by rest within 2-5 minutes
• Buttock/thigh claudication + erectile dysfunction = Leriche syndrome (aortoiliac disease)

Critical Limb Ischaemia (CLI)

• Rest pain: severe pain in foot/toes, worse at night, relieved by hanging leg over bed
• Ulceration: typically at pressure points (toes, heel), painful
• Gangrene: dry or wet
• Tissue loss

Examination Findings

• Diminished or absent peripheral pulses
• Femoral, popliteal, dorsalis pedis, posterior tibial — compare bilaterally
• Cool, pale, or mottled skin
• Trophic changes: hair loss, shiny skin, thickened nails, muscle wasting
• Buerger test: leg pallor on elevation (Buerger angle <20° = severe ischaemia); rubor on dependency
• Audible bruits (femoral, iliac)

Red Flags

• Rest pain (critical ischaemia — needs urgent revascularisation)
• Non-healing ulcer or gangrene
• Acute limb ischaemia (see separate topic)
• ABPI <0.5

Bedside

• ABPI (ankle-brachial pressure index): key diagnostic test
  • Normal: 1.0-1.3
  • PAD: <0.9
  • Severe: <0.5 (critical ischaemia)

  • 1.3: calcified arteries (falsely high — common in diabetes)

• Pulse palpation: femoral, popliteal, DP, PT
• Buerger test: angle of pallor

Bloods

• HbA1c/fasting glucose: diabetes
• Lipid profile: dyslipidaemia
• FBC: anaemia, polycythaemia
• U&Es: renal function (CKD is a risk factor and comorbidity)
• Coagulation: pre-interventional

Imaging

• Duplex ultrasound: first-line imaging; identifies stenosis location and severity
• CT angiography: detailed arterial anatomy pre-intervention
• MR angiography: alternative (avoids iodinated contrast)
• Digital subtraction angiography: gold standard; usually performed at time of planned intervention

Special Tests

• Toe-brachial pressure index: useful when ABPI falsely elevated (calcified arteries in diabetes)
• Exercise ABPI: post-exercise drop confirms PAD in borderline cases
• Transcutaneous oxygen pressure (TcPO₂): assesses tissue perfusion; <30 mmHg suggests critical ischaemia

Non-pharmacological

• Smoking cessation: most important intervention (refer to NHS Stop Smoking service)
• Supervised exercise programme (SEP): NICE CG147 first-line for claudication
  • ≥2 hours/week for ≥3 months
  • Walk to near-maximal pain, rest, repeat
  • Improves claudication distance by ~50-200%
• Foot care: especially in diabetic patients; daily inspection, appropriate footwear

Pharmacological

• Antiplatelet: clopidogrel 75mg OD (NICE preferred for PAD) or aspirin 75mg OD
• Statin: atorvastatin 80mg OD (high-intensity)
• Antihypertensive: ACEi (ramipril — HOPE trial) preferred if tolerated
• Diabetes optimisation: HbA1c target <48-53 mmol/mol
• Naftidrofuryl oxalate 100-200mg TDS: vasodilator; only peripheral vasodilator recommended by NICE if exercise programme not suitable
• Avoid cilostazol in UK (not routinely recommended by NICE)
• Analgesia: opioids may be needed for rest pain in CLI

Surgical/Interventional

Indications:

• Critical limb ischaemia (rest pain, tissue loss) — urgent
• Lifestyle-limiting claudication despite ≥3 months supervised exercise

Options:

• Percutaneous transluminal angioplasty (PTA) ± stenting: first-line for short-segment disease (especially iliac and femoropopliteal)
• Surgical bypass: for extensive disease; autologous vein graft (long saphenous) preferred over synthetic
• Endarterectomy: for localised disease (especially aortoiliac)
• Amputation: for irreversible tissue loss, uncontrollable infection, or non-reconstructable disease
  • Below-knee amputation preferred (better rehabilitation potential)

Referral Criteria

• Critical limb ischaemia: urgent vascular referral (<2 weeks)
• Lifestyle-limiting claudication not responding to exercise: vascular assessment
• Non-healing ulcers: urgent vascular referral
• Acute limb ischaemia: emergency vascular referral

• Claudication: ~75% remain stable or improve with conservative management; ~5-10% progress to CLI over 5 years
• Critical limb ischaemia: major amputation rate ~25% at 1 year without revascularisation
• PAD patients: 5-year cardiovascular mortality ~20-30% (MI and stroke are leading causes of death)
• Post-bypass surgery: 5-year patency ~60-80% (vein graft) vs ~40-60% (prosthetic graft)
• Post-angioplasty: restenosis rate depends on location and lesion length
• Smoking cessation improves outcomes more than any other intervention
• Supervised exercise: increases walking distance by 50-200%

Fontaine Classification

ABPI Interpretation