Peripheral Arterial Disease

Peripheral Arterial Disease (PAD) is a common manifestation of systemic atherosclerosis. The most frequent symptom is Intermittent Claudication (IC), which is cramp-like muscle pain on exertion that is relieved by rest (usually in the calves). PAD is a marker of high cardiovascular risk; these patients are more likely to die from MI or stroke than to lose a limb. At the severe end of the spectrum is Chronic Limb-Threatening Ischaemia (CLTI), characterized by rest pain, ulceration, or gangrene. Diagnosis is primarily clinical and supported by the Ankle-Brachial Pressure Index (ABPI), where a value of <0.9 is diagnostic. Management revolves around 'best medical therapy' (high-dose statins and antiplatelets) and supervised exercise programmes. Revascularisation (angioplasty or bypass) is reserved for CLTI or claudicants whose lifestyle is severely limited despite conservative measures.

PAD is primarily caused by atherosclerosis (90%). The process involves sub-endothelial lipid deposition, macrophage recruitment (foam cells), and the formation of a fibrous plaque in the muscular arteries (e.g., femoral, popliteal, iliac). These plaques narrows the arterial lumen, creating a flow-limiting stenosis. During exercise, the increased metabolic demand of the distal muscles exceeds the oxygen delivery (ischaemia), leading to anaerobic metabolism and the production of lactic acid/adenosine, which triggers pain (claudication). In CLTI, the stenosis or occlusion is so severe that perfusion is insufficient to meet the basic metabolic needs of the tissue at rest. Other causes of PAD include Buerger's disease (thromboangiitis obliterans, related to heavy smoking) and vasculitis.

Intermittent Claudication: Pain location depends on the site of arterial disease (Aorto-iliac = buttock/thigh pain, Femoro-popliteal = calf pain). Rest pain in CLTI is often worse at night (gravity-dependent) and relieved by hanging the foot over the edge of the bed. Examination: 1. Inspection: Muscle wasting, hair loss, thickened nails, 'punched-out' ulcers (usually on toes or pressure points), gangrene. 2. Palpation: Weak or absent distal pulses (dorsalis pedis, posterior tibial); cool skin. 3. Special tests: Buerger's angle <20° indicates ischaemia. Acute Limb Ischaemia (the 6 Ps) is a surgical emergency, unlike the chronic presentation of PAD.

1. Bedside: Ankle-Brachial Pressure Index (ABPI) using a Doppler probe. (Normal 1.0-1.2; Claudication 0.6-0.9; CLTI <0.5). Beware: ABPI may be falsely high (>1.4) in diabetics with calcified, incompressible vessels.
2. Bloods: Glucose/HbA1c (Diabetes), Lipid profile, U&Es, FBC (anaemia/polycythaemia).
3. Imaging (for revascularisation planning): Duplex Ultrasound (first-line); CT or MR Angiography (Gold standard for anatomy). Digital Subtraction Angiography (DSA) usually done during intervention.

1. Secondary Prevention (All patients): Smoking cessation (essential), Atorvastatin 80mg, Clopidogrel 75mg (first-line antiplatelet), tight Blood Pressure and Diabetes control.
2. Intermittent Claudication: Supervised exercise programme (2 hours a week for 3 months). If no improvement, consider Naftidrofuryl oxalate. Angioplasty/Bypass only if lifestyle is severely affected.
3. CLTI/Severe disease: Urgent referral to vascular surgeons. Surgical revascularisation (Bypass) or endovascular (Angioplasty/Stenting). Pain management.
4. Foot care: Diabetic foot team involvement, appropriate footwear, and regular podiatry.