3.1. Peripheral Arterial Disease (PAD)

📄 Definition

Peripheral arterial disease (PAD) is a manifestation of systemic atherosclerosis causing stenosis or occlusion of arteries, primarily affecting the lower limbs. It ranges from asymptomatic disease to critical limb ischaemia.

⚠️ Classification

  • Asymptomatic PAD: reduced pulses, ABPI <0.9 but no symptoms

  • Intermittent Claudication: reproducible leg pain with exertion, relieved by rest

  • Critical Limb Ischaemia (CLI): chronic pain at rest, ulceration, or gangrene

🛡️ Risk Factors – Mnemonic: ATHEROSE

  • Age >60

  • Tobacco use (most significant modifiable)

  • Hypertension

  • Elevated cholesterol

  • Renal impairment (CKD)

  • Obesity

  • Sedentary lifestyle

  • Endocrine: Diabetes mellitus

Investigations 

🥇 First-Line

  • ABPI (Ankle-Brachial Pressure Index):

    • <0.9 = diagnostic of PAD

    • <0.5 = severe disease

  • Duplex Doppler Ultrasound – assess blood flow and stenosis

🎯 EXAM ANCHOR 1 – THE ABPI INTERPRETATION

  • The Ankle-Brachial Pressure Index (ABPI) is your first-line diagnostic test.

    • Normal: 1.0 – 1.2

    • PAD: < 0.9

    • Critical Limb Ischaemia: < 0.5 (or ankle pressure < 50 mmHg)

    PARA TRAP – The Calcified Vessel: In patients with Diabetes or CKD, arteries can become calcified and non-compressible. This leads to a falsely high ABPI (> 1.2). If you see a high ABPI in a symptomatic diabetic, the next step is a Toe-Brachial Pressure Index (TBPI) or Duplex Ultrasound.

🥈 Second-Line

  • MR Angiography or CT Angiography – pre-intervention planning

  • Bloods: FBC, U&Es, HbA1c, Lipids, LFTs, ESR/CRP

  • ECG – evaluate cardiovascular risk

📋 Clinical Features – 

Mnemonic: 6 Ps (acute) and CLAUDICATE (chronic)
Acute Limb Ischaemia – 6 Ps:

  • Pain

  • Pallor

  • Pulselessness

  • Paralysis

  • Paraesthesia

  • Perishing cold

Chronic PAD – Mnemonic: CLAUDICATE

  • Cramping calf pain

  • Loss of hair

  • Abnormal pulses

  • Ulcers (arterial)

  • Dry, shiny skin

  • Intermittent claudication

  • Cool peripheries

  • ABPI <0.9

  • Toe pallor

  • Erectile dysfunction (Leriche syndrome)

🎯 EXAM ANCHOR 1 – CHRONIC VS. ACUTE FEATURES

  • Intermittent Claudication: Pain is reproducible (occurs at the same distance every time) and relieved by rest.

  • Critical Limb Ischaemia (CLI): Defined by the “Triad of Trouble”:

  1. Rest Pain: Burning pain at night, relieved by hanging the leg over the edge of the bed (gravity helps perfusion).

  2. Ulceration: Typically “punched out” ulcers on the toes or heels.

  3. Gangrene.

Management – Mnemonic: PAD CARE

  • Prevention – smoking cessation, weight reduction, exercise

  • Antiplatelet – clopidogrel first-line

  • Dual risk factor control – manage BP, lipids, diabetes

  • Cilostazol (for symptom relief in intermittent claudication)

  • Angioplasty or stenting – severe symptoms or CLI

  • Revascularisation – surgical bypass if angioplasty not feasible

  • Education – foot care, PAD risk understanding

🎯 EXAM ANCHOR 1 – MANAGEMENT (NICE CG147)

  • The PARA tests your ability to prioritize medical management before jumping to surgery.

  1. Antiplatelet: Clopidogrel 75mg is the first-line choice (Aspirin is second-line for PAD).
  2. Statin: Atorvastatin 80mg (High-intensity) for all patients.
  3. Supervised Exercise Programme: This is the first-line non-drug treatment for intermittent claudication. Patients should walk until the pain is near-maximal, then rest, then repeat for 30–45 mins, 3x per week.
  4. Naftidrofuryl oxalate: If exercise and risk factor modification fail, this can be offered for symptom relief (NICE alternative to Cilostazol).
  5.  

⚠️ Complications

  • Critical limb ischaemia

  • Amputation

  • Ulceration

  • Cardiovascular morbidity (MI, stroke)

🔎 Key PARA Exam Traps

  • Buerger’s Test: Raising the leg causes it to go pale (pallor), and lowering it causes it to turn a deep red (reactive hyperaemia). This is a classic sign of severe ischaemia.

  • Foot Care: Diabetic patients with PAD need referral to a Podiatrist. Even a small nick during a nail trim can lead to a non-healing ulcer and amputation.

  • Beta-Blockers: There is an old myth that Beta-blockers are contraindicated in PAD. NICE states they are safe to use if needed for other conditions, though they may rarely worsen symptoms in some patients.

🔺 Last updated in line with NICE CG147 – Peripheral arterial disease: diagnosis and management

Published: August 2012 • Last updated: October 2020

  • PARA-aligned, reviewed February 2026


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