Peripheral Vascular Disease

 

• Definition and pathophysiology

  • Aka peripheral arterial (occlusive) disease.
  • Chronic PVD is due to atherosclerosis of peripheral arteries. Usually affects legs but can affect arms.
  • Acute limb ischaemia results from total occlusion of an artery, due to progression of longstanding disease or an acute embolus (e.g. from AF). Tissue necrosis results within 6 hours if untreated.
  • PVD is often synonymous with arterial occlusive disease. However, other types of peripheral vascular disease include: venous disease, aneurysmal disease, and carotid artery disease.

• Signs and symptoms

  Chronic PVD

  Locations of pain (and affected arteries):

  • Upper ⅔ of calf (superficial femoral artery). Commonest site.
  • Buttock and hip (aortic and iliac artery). 2nd commonest site.
  • Thigh (iliac or common femoral artery).
  • Lower ⅓ of calf (popliteal artery).
  • Foot (tibial or peroneal artery).

  Claudication

  • Claudication is a predictable, reproducible pain on exertion caused by ischaemia of the muscle, which is relieved by rest.
  • 30% have classic intermittent claudication but most have a more atypical pattern, with some being asymptomatic. There may be a limp.
  • Quantify severity by asking about how many yards they can walk before they have to stop because of the pain, on the flat, at a normal pace, on their best day.

  Critical limb ischaemia

  • Rest pain, unrelieved by medication for ≥2 weeks and/or evidence of tissue loss (ulcer or gangrene).
  • In the context of neuropathy (e.g. co-morbid diabetes), pain may be absent.
  • Pain is in the feet and toes, rather than calves. Worse at night due to reduced gravitational pull, so patient may sleep in a dependent position to try and maintain perfusion. This can result in a swollen leg, which may also be red from metabolite-triggered capillary dilation.

  Fontaine classification

  1. Asymptomatic.
  2. Intermittent claudication. 2a if stop >200m, 2b if <200m.
  3. Rest or nocturnal pain.
  4. Necrosis/gangrene.

  Acute limb ischaemia

  Presents with the 6 Ps:

  • Pain at rest.
  • Pulseless
  • Pale
  • Parasthesia
  • Perishingly cold.
  • Paralysis is a late feature suggesting irreversible damage.

• DDx: Leg pain

  Musculoskeletal e.g. osteoarthritis.

  Vascular:

  • PVD
  • DVT

  Neurospinal:

  • Disc degeneration.
  • Spinal stenosis.

  Neuropathic:

  • Diabetes
  • Alcoholic neuropathy.

• Investigations

  Initial investigations

  Diagnose with ankle-brachial pressure index (ABPI):

  • The ratio of systolic blood pressure at the ankle and arm, measured using doppler US.
  • Procedure: take after 10 minutes at rest, and use the sides with the highest measurements.
  • Results: roughly, <0.9 is claudication, <0.6 is rest pain, <0.3 is impending gangrene.

  Cardiovascular investigations:

  • ECG, lipids, glucose, BP.

  Imaging

  Duplex US:

  • Combines usual grayscale US image with colour-doppler US to visualise flow.
  • Helps determine site of disease.

  Angiography if surgery considered:

  • MR angio is a good choice when available.
  • CT angio is better for showing wall abnormalities (e.g. aneurysm) and more available than MRA. Risks: contrast nephropathy, radiation.
  • Intra-arterial digital subtraction angiogram (invasive): gold standard that also allows treatment. Risks: thrombus embolisation and/or vessel puncture, with 1/100 leading to limb loss.

• Management

  Conservative and medical:

  • Advise patients to keep active. Can refer to exercise rehabilitation programme.
  • Cardiovascular disease prevention. Clopidogrel is 1st line antiplatelet therapy in PVD.
  • Foot care.
  • The vasodilator naftidrofuryl can slightly increase walking distance.

  Revascularisation:

  • Indications: treatment-resistant disease, critical limb ischaemia, acute limb ischaemia.
  • Options: surgical bypass, surgical endarterectomy, radiological angioplasty and stenting (easier with large vessels e.g. iliac). Bypass may involve grafting native vessel – e.g. saphenous vein for femoro-popliteal bypass – or synthetic vessel – e.g. for aorto-iliac or ilio-femoral bypass.
  • Acute limb ischaemia: heparin IV then embolectomy with Fogarty catheter. Thrombolysis with alteplase if not surgically fit.
  • Reperfusion injury may result from revascularisation, due to the systemic release of substances in the damaged tissue e.g. K+, myoglobin. Other complications include graft failure and limb loss.

  Amputation:

  • A last resort, considered in patients with ulceration and gangrene.

• Complications and prognosis

  • Arterial ulcers.
  • Gangrene
  • Amputation