Part 2: Clinical Evaluation and Investigation.

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Clinical Evaluation of Peripheral Arterial Disease.

The aim of a clinical evaluation is to be able to put patients into one of three categories.

a) Claudication - mild/moderate. This patient gets pain usually in the calf, bought on by exercise, relieved by rest. He can walk from 100 yards to 1/4 mile.

b) Incapacitation claudication. The symptoms are the same but the claudication distance is much shorter to the extent that the patient cannot do his job or if retired, has difficulty performing survival functions like shopping, housekeeping etc.

c) Critical ischaemia. The patient has rest pain which often wakes him at night and may force him to sleep in a chair. It may be accompanied by ulceration or gangrene with ankle pressure of 40mm Hg or less.

Clinical Examination

The presence of elevation pallor and dependency rubor and/or trophic changes usually indicate significant chronic ischaemia. It is usually found in patients with incapacitating claudication or critical ischaemia.

The finding of a normal (2), reduced (1) or absent (0) pulse is the most telling sign indicating the presence of absence of PAD. It is also useful to listen for bruits. A bruit over the femoral artery in the groin indicates femoral or iliac stenotic disease proximally. It is also possible to hear a superficial femoral artery (SFA) bruit by listening over the medial thigh. Ideally bruits should be listened for before and after exercise. In the presence of a significant stenosis (>50%), after exercise the pulse gets weaker and the bruit louder.

A patient with an SFA occlusion will have a palpable femoral but absent popliteal pulse. There will be no trophic changes or Buerger's sign or ischaemic ulcers. If these are present it usually means that there is disease at another level such as the infracrural vessels. An occlusion of the aorta or iliac vessels usually presents only with claudication. The skin nutrition can be normal. This is because of good collaterals round the pelvis. By contrast, a diabetic can present with critical ischaemia of a foot yet have normal vessels all the way to the popliteal artery. This is because the disease is infracrural and the more distal the disease, the less the capacity to develop collateral circulation and hence the more severe the disease.

Biochemical Investigations:

i. Duplex Scanning.

This can assess the whole lower limb arterial tree but it is time consuming. We find it useful to evaluate whether a patient is suitable for an iliac or femoral angioplasty - particularly in elderly patients where one is looking for the smallest intervention to alleviate symptoms.

ii. Magnetic Resonance Angiography (MRA).

This is useful for patients who won't tolerate contrast. it is also useful to evaluate renal artery stenosis, aorto-iliac and femoral disease but is less useful for more distal disease. At some stage it will probably replace angiography but not quite yet.

iii. Angiography.

This is still our gold standard. Modern angiography is digital subtraction allowing the bony skeleton to be subtracted from the picture leaving only the arteries. A good study should include the renal arteries t the feet. For patients with poor renal formation - CO2 angiography is an option. It is a 'day surgery' procedure.