Peripheral Arterial Disease (PAD)

Related Subjects: | Ankle-Brachial Pressure Index (ABPI) and Peripheral Vascular Disease | Peripheral Arterial Disease (PAD) | Abdominal Aortic Aneurysm (AAA) | Carotid Endarterectomy | Buerger's disease (Thromboangiitis obliterans) | Leriche syndrome (aortoiliac occlusive disease)

🩸 Peripheral Arterial Disease (PAD) (often loosely called “PVD”) is systemic atherosclerosis affecting limb arteries, most commonly the legs. It is a powerful marker of coronary and cerebrovascular disease—many patients with PAD are more likely to die from MI or stroke than from limb loss. Clinically important red flags are rest pain, tissue loss (ulcer/gangrene), and features of acute limb ischaemia (the “6 Ps”).

ℹ️ About

• 🦵 Legs are most commonly affected; PAD frequently co-exists with carotid and coronary disease.
• 📈 Often under-recognised: patients may be asymptomatic yet still have high cardiovascular risk.
• ⚠️ Rest pain or ulcer/gangrene = urgent vascular assessment (critical limb ischaemia / chronic limb-threatening ischaemia).

🧬 Pathophysiology

• 🧱 Atherosclerosis dominates: lipid deposition + inflammation → fibrous plaque in medium/large arteries, especially at bifurcations where flow is turbulent.
• 🩸 Progressive luminal narrowing reduces perfusion; symptoms appear when demand rises (exercise) → intermittent claudication.
• 💥 Plaque rupture can trigger thrombosis and sudden deterioration → acute limb ischaemia.
• 🔁 Collaterals may develop, but often fail to meet demand in advanced disease.
• 🩺 In diabetes/CKD, medial arterial calcification can make vessels incompressible → ABPI can be falsely high (consider toe pressures/duplex).

🚬 Risk Factors

• 🚬 Smoking (most important modifiable risk).
• 🍩 Diabetes mellitus (accelerates atherosclerosis; increases distal disease and ulcer risk).
• 🍔 Dyslipidaemia, 💓 hypertension, ⚖️ obesity/inactivity, metabolic syndrome.
• 👴 Increasing age, male sex, family history of premature vascular disease.
• 🧑‍⚕️ CKD, sedentary lifestyle, poor diet.
• 🩸 Buerger’s disease (younger smokers; inflammatory thrombotic disease rather than classic atherosclerosis).

🧑‍⚕️ Clinical Features

• 🚶 Intermittent claudication: reproducible exertional pain (calf/thigh/buttock) relieved by rest.
• 🌙 Rest pain: severe foot/toe pain (often at night), relieved by dependency (hanging foot over bed) → suggests severe ischaemia.
• 🩹 Tissue loss: “punched-out” ulcers, poor healing, gangrene.
• 🦵 Signs: cool limb, hair loss, shiny/atrophic skin, thickened nails, slow cap refill, bruits, reduced/absent pulses.
• 👨‍🦽 Leriche syndrome (aorto-iliac): buttock/thigh claudication ± impotence.
• 🧠 Carotid disease association: history of TIA/stroke should heighten systemic risk management urgency.

📍 Localising Claudication to Vessels

• 🍑 Buttock/hip → aorto-iliac.
• 🦵 Thigh → common femoral or aorto-iliac.
• 👟 Upper 2/3 calf → superficial femoral.
• 🧦 Lower 1/3 calf → popliteal.
• 🦶 Foot → tibial/peroneal (often diabetic distal disease).

❓ Key History Points

• ⏱️ Onset, progression, and whether symptoms are stable vs worsening.
• 🚶 Claudication distance (how far before pain; what speed/gradient).
• 📍 Pain location (helps localisation) and relieving factors (rest vs dependency).
• 🩸 Cardiovascular history: angina/MI, TIA/stroke, AF, heart failure.
• 💊 Current meds and adherence (statin/antiplatelet/diabetes control), smoking/alcohol, infection symptoms (ulcer).

🔍 Examination

• 👀 Inspect: colour (pallor/dependent rubor), trophic changes, ulcers, infection, gangrene.
• ✋ Palpate pulses: femoral → popliteal → posterior tibial → dorsalis pedis; compare sides.
• 👂 Auscultate for bruits over femoral/iliac regions where relevant.
• 🦵 Buerger’s test: elevation pallor, dependency rubor (suggests poor arterial inflow).

📈 Severity (how bad is the ischaemia?)

🧠 Think of limb ischaemia as a supply–demand mismatch. As arterial flow falls, the limb can cope at rest (until it can’t). Symptoms move from exertional pain → rest pain/tissue loss → sudden threatened limb when there’s an abrupt occlusion.

• 🚶‍♂️ Intermittent claudication (IC): arterial supply is adequate at rest but cannot meet oxygen demand on exertion → cramp-like calf/thigh/buttock pain brought on by walking and relieved by rest.
  Exam pearl: distance-limited, reproducible, and improves with stopping (not usually with posture change).
• 🦶🔥 Critical limb ischaemia / CLTI (formerly “CLI”): arterial supply is insufficient even at rest → rest pain (often worse at night, relieved by hanging the leg down) and/or tissue loss (ulceration/gangrene).
  Why it matters: this is a limb-threatening emergency requiring urgent vascular assessment for revascularisation planning.
• ⚡ Acute limb ischaemia (ALI): sudden reduction in limb perfusion (embolus, thrombosis, graft/stent occlusion, trauma/dissection) causing rapidly evolving ischaemia.
  Exam pearl: the “6 Ps” — Pain, Pallor, Pulselessness, Paraesthesia, Paralysis, Poikilothermia (cold) — with paraesthesia/paralysis suggesting a threatened limb and needing immediate senior/vascular escalation.

🚨 Critical Limb Ischaemia / Chronic Limb-Threatening Ischaemia (CLTI)

• 🔥 Severe, constant pain at rest (often burning in forefoot/toes), especially nocturnal.
• 🩹 Non-healing ulcers, infection, tissue loss; smooth shiny pallid skin.
• ⚫ Gangrene (black toes/foot) → urgent same-day vascular input.
• 💉 Goal is revascularisation where possible (endovascular or bypass); amputation if non-salvageable.

⚡ Acute Limb Ischaemia (don’t miss)

• 🚑 Sudden onset limb symptoms with the 6 Ps: pain, pallor, pulselessness, perishingly cold, paraesthesia, paralysis.
• ⛔ Treat as time-critical: limb (and sometimes life) at risk → urgent vascular/ED pathway.

🔬 Investigations

• 🧪 Baseline bloods: FBC, U&E, LFTs, lipids, HbA1c/glucose, CRP if ulcer/infection suspected.
• 📈 ECG (AF/IHD/LVH); echo if cardiac source or heart failure suspected.
• 🩺 ABPI (ankle-brachial pressure index):
  • Normal: 1.0–1.4
  • PAD likely: <0.9
  • Severe disease: <0.5
  • ⚠️ If >1.4 (incompressible; common in diabetes/CKD) → consider toe pressures or duplex.
• 📊 Duplex Doppler ultrasound: first-line imaging to map disease and flow.
• 🖼️ CT angiography / MR angiography: if considering intervention.
• 🩻 Catheter angiography: detailed anatomy/run-off, usually as part of endovascular planning.

💊 Management (symptoms + cardiovascular risk reduction)

• 🚭 Smoking cessation (biggest single intervention for outcomes).
• 🏃 Supervised exercise therapy (improves claudication distance; supports collateralisation and conditioning).
• 🦶 Foot care (especially in diabetes): daily inspection, footwear, podiatry for callus/ulcer prevention.
• 💊 Antiplatelet (e.g. clopidogrel or aspirin per local/NICE approach) to reduce CV events.
• 💊 High-intensity statin (e.g. atorvastatin 80 mg if tolerated) and aggressive risk-factor control (BP, diabetes, weight).
• 💊 ACE inhibitor/ARB where indicated; manage AF and other embolic sources appropriately.
• 🔧 Endovascular: angioplasty ± stent for suitable lesions (often first-line for focal disease).
• 🔨 Surgery: bypass grafting (e.g. fem-pop) / endarterectomy for extensive or unsuitable anatomy.
• 🦿 Amputation: last resort for irreversible gangrene, uncontrolled infection, or failed revascularisation; preserve knee joint if feasible for prosthetic function.

🚩 Red Flags (urgent escalation)

• 🌙 Rest pain (especially nocturnal) needing dependency to relieve.
• 🩹 Non-healing ulcer, spreading infection, or gangrene.
• ⚡ Sudden severe pain + cold/pale limb + neuro deficit (acute limb ischaemia).
• 📉 Rapid deterioration in walking distance or new tissue loss.

📚 Teaching Pearls

• ❤️ Treat PAD as a cardiovascular disease equivalent: the limb symptoms are only one part—the systemic risk is the main killer.
• 🩺 ABPI can be misleading in diabetes/CKD (calcified arteries) → don’t be falsely reassured by “normal/high” ABPI if the story fits.
• 🦶 In diabetics, distal disease + neuropathy → ulcers may present late; inspect carefully and involve podiatry early.
• 🧑‍⚕️ Best outcomes come from a multidisciplinary approach: vascular, diabetes, podiatry, tissue viability, rehab.

🧪 Cases

• Case 1 — Intermittent Claudication: 66-year-old smoker with calf pain after 200 m, relieved by rest; cool legs, weak DP pulses. Plan: ABPI/duplex, supervised exercise, smoking cessation, antiplatelet + statin, optimise BP/DM.
• Case 2 — CLTI: 74-year-old with nocturnal foot rest pain relieved by dangling; dusky toes + non-healing ulcer. Plan: urgent vascular referral, analgesia, antibiotics if infected, imaging for revascularisation (angioplasty/bypass).
• Case 3 — Acute Limb Ischaemia: 62-year-old with AF and sudden painful cold pale leg with sensory/motor loss. Plan: emergency pathway, IV heparin (if not contraindicated), urgent vascular intervention (embolectomy/thrombectomy).

📖 References

• NICE CG147 – Peripheral arterial disease: diagnosis and management
• NICE CKS – Peripheral arterial disease
• NICE CKS – Intermittent claudication