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Peripheral Arterial Disease/Chronic Limb Ischaemia

Peripheral arterial disease (PAD) is when there's significant atherosclerotic narrowing of arteries distal to the aortic arch. Risk factors for it include Old age, Smoking, Alcohol, Hyperlipidaemia, HTN, DM, Diet, Obesity, and Family hx.

Peripheral Arterial Disease - National Heart Lung and Blood Institute

Complications of it include:

  • Acute limb ischaemia

  • Arterial ulcers (small, punched-out, painful ulcers)


Differentials include:

  • Neuropathic ulcers (e.g. in diabetes) - painless, warm foot with sensory loss, and often present on pressure areas or places that have been injured

  • Venous ulcers - irregular, shallow, sloughy area in gaiter area

  • Nerve root compression - sharp, shooting pain, radiating down the leg

  • Spinal stenosis - bilateral pain and weakness in buttocks and posterior leg, worse on extension (standing), and relieved by flexion (bending)


Presentation

Main presenting symptom here is Intermittent Claudication - Crampy calf/thigh/buttock pain on walking, and relieved by rest.


O/E - The things that may be found include:

  • Pale, cold leg

  • Ulcers

  • Poorly healing wounds

  • Weak or absent pulses


Critical Limb ischaemia - Severe PAD, where there’s severely impaired limb perfusion. Main presenting symptom is burning pain at rest, which is relieved by dangling feet over edge of bed. Ulcers and gangrene may also be seen. These patients will be at a high risk of needing an amputation.


Leriche syndrome - Bilateral common iliac stenosis, presenting with a triad of Buttock/thigh/calf pain + Absent femoral pulses + Erectile dysfunction


Investigations

1st line investigation to do is an ABPI (Ankle-Brachial Pressure Index). As the lower limb arteries are stenosed, the BP at the ankles will be lower. This plus a normal BP of the brachial arteries will lead to a decrease in ABPI. This result therefore gives an indication to the degree of PAD:

  • 0.8 - 1.3 = Normal

  • 0.5 - 0.8 = Mild/moderate PAD

  • < 0.5 = Severe PAD


N.B. An ABPI of > 1.3 indicates arterial calcification. This makes it harder to compress the artery, therefore resulting a misleadingly high ABPI e.g. in Diabetics.

Ankle-Brachial Pressure Index Test - National Heart Lung and Blood Institute

Other investigations to do include:

  • Full CVS risk assessment - FBC, BP, HbA1c, Lipids, ECG

  • Buerger’s Test - To do this, lie the patient supine and slowly raise their leg. The angle at which their sole goes pale is called Buerger’s angle (the smaller the angle, the worse the ischaemia). Then dangle the patient’s legs off the bed and observe for reactive hyperaemia in which the limb very red and hot.

  • Duplex USS (for site and severity of stenosis) - quick scan that can be done to assess blood flow

    • Handheld doppler can be done at the bedside

  • CT Angiogram - Very important scan to see occlusions and also for surgeons to plan on how best to manage the patient e.g. angioplasty, bypass


Management

Conservative - Supervised exercise, Smoking cessation, HTN/DM control


N.B. Exercise is very important in these cases of chronic limb ischaemia as it encourages the formation of collateral blood vessels to help with perfusion of the limb.


Medical - The options here are:

  • Antiplatelets, Statins

  • Naftidrofuryl oxalate (vasodilator) as symptomatic relief if supervised exercise not effective and patient doesn’t want surgery


If conservative and medical options are no longer effective, the patient can be offered revascularisation therapy:

  • Angioplasty (+/- stenting)

  • Surgical bypass

    • Amputation may be done if revascularisation isn’t possible



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