On your advice he agrees to see a vascular surgeon, who recommends that an arterial duplex scan is performed. This is shown in Figures 23.1, 23.2 and 23.3. Figure 23.2 demonstrates an occluded segment of superficial femoral artery (SFA). The waveforms above this lesion (23.1) are normal but the waveforms distally (23.3) are damped consistent with the occlusion just proximal to this segment. Subsequently he recommends a CT angiogram (shown in Figure 23.4). These are AP views with the patient’s right leg on the left side of Figure 23.1.

Figure 23.1

Figure 23.2

Figure 23.3

Figure 23.4

Q.6

What does the angiogram show?

There is diffuse calcification of all vessels. There is an occlusion of the right distal superficial femoral and proximal popliteal artery confirmed with good below-knee vessels.

Q.7

How are you going to manage this problem?

An attempted angiography was unsuccessful and a reverse vein femoropopliteal bypass was performed. This is successful in improving his lower limb circulation but is complicated by a cerebrovascular event involving his non-dominant hemisphere for which he requires 3 months of intensive rehabilitation.

Answers

A.1 His history of calf pain on exercise relieved by rest is typical of intermittent claudication. You may also consider spinal canal stenosis in your differential diagnosis, but relief of the pain by rest points to peripheral vascular disease as the cause of the problem. As such, you would like to know if he has risk factors for cardiovascular disease and any history of other previous or current problems related to his cardiovascular system.

Major risk factors which you must ask about are:

• Hypertension (duration and adequacy of control).

• Diabetes mellitus (duration, Hb A1C).

• Smoking (pack years).

• Hyperlipidaemia.

Typical cardiovascular co-morbidities are:

• Ischaemic heart disease (especially current but also past symptoms).

• Cerebrovascular accidents or transient ischaemic attacks (TIAs).

• Abdominal aortic aneurysm.

A.2

• The cardiovascular system should be examined for hypertension and evidence of cardiac dysfunction. The carotid arteries should be examined for bruits.

• The respiratory system should be examined for evidence of smoking-related chronic airways obstruction.

• His abdomen should be examined carefully for evidence of aortic aneurysm (present in 10–15% of claudicants).

• His peripheral pulses, including the femoral, popliteal, dorsalis pedis and posterior tibial pulses, should be examined. Provided a pulse can be felt, the quality of the femoral pulse will be assessed (for strength and dilatation) and bruits listened for.

• The legs should be assessed for evidence of ischaemia. This includes the colour and temperature of the limbs. If ischaemia is advanced, the foot will become pale when the leg is elevated and deeply red when it is then lowered to a dependent position. Reduced blood flow through the capillary bed will result in increased uptake of oxygen from the blood by the tissues and this may cause the limb to take on a cyanotic hue. An ischaemic foot tends to be relatively cool.

• The limb should also be examined for areas of ulceration and necrosis – so-called ‘dry gangrene’ or mummification. There may also be evidence of muscle atrophy. As the ischaemia worsens, atrophy of the skin progresses and it appears shiny and scaly. Loss of hair and thickening of the nails are unreliable signs of ischaemia because they are widely present in the normal population.

• Objective measurement of foot perfusion with Doppler ultrasound is essential – clinical judgement, including palpation of pedal pulse, is fairly inaccurate.

• You should measure the ankle–brachial index (ABI).

At this stage the patient does not warrant extensive investigation, but the following should be performed:

• Blood sugar.

• Lipid profile.

• Serum biochemistry (looking for any renal impairment).

A.3 By comparing the blood pressures in the brachial (which is assumed to be normal) and the vessels at the ankle (dorsalis pedis and posterior tibial), an estimation can be made of the adequacy of arterial blood flow in the leg. In an individual with normal arteries the ankle–brachial index is expected to be 0.9–1.2, Most claudicants often have an ABI of 0.5–0.9. A value below 0.5 is often associated with rest pain and when the ratio gets to less than 0.3, viability of the limb may be in jeopardy.

A.4 You should advise him in simple language that:

• The pain in his legs is due to arterial occlusive disease, resulting in insufficient blood getting to the muscles, which is most noticeable during exercise.

• He should continue to walk within his levels of comfort. There is no advantage in walking ‘through’ the pain. He should stop when pain comes on, wait a minute or two for the discomfort to settle then go on.

• It is absolutely vital that he stops smoking because if he does not the disease will progress and he could develop gangrene or another complication such as a heart attack or stroke.

• He needs to take low-dose aspirin.

• There is evidence that there is some benefit to commencing a statin, even if his lipid profile is normal.

• Apart from Doppler studies, he does not need any other investigations.

• In addition to the Doppler studies previously described, however, it may be worth considering a carotid duplex scan to clarify whether a stenosis is present (bruit heard on initial physical examination).

• He needs to take care of his feet and avoid local trauma.

• He should reduce his cholesterol intake by following a low-cholesterol diet. If a lipid profile check 3 months later does not show improvement lipid-lowering agents will be started. There is some evidence that a statin should be commenced in individuals with symptomatic lower limb arterial disease, irrespective of the lipid level.

A.5 He now has rest pain: the blood supply to the limb has deteriorated to such an extent that the leg’s viability is threatened. You must take action:

• Repeat your physical examination.

• Repeat the Doppler studies.

• Reinforce your advice on the need to stop smoking.

• Make the patient aware of the high risk of losing his limb (or part of it).

• Arrange for the patient to be seen by a vascular surgeon, who will:

– arrange imaging studies

– suggest some form of intervention to try and improve blood supply to his foot.

A.6 Both a non-subtracted and subtracted angiogram are shown to assist with vessel orientation. The angiogram demonstrates normal aortoiliac arteries. The common femoral and profunda femoris vessels are also widely patent. Both superficial femoral arteries (SFA) (from groin to adductor canal) are extensively diseased, with a 7–8 cm long occlusion of the right SFA being shown. Collateral vessels via the profunda femoris arteries fill the popliteal arteries.

As a result of the more severe occlusive disease on the right side, the contrast filling the popliteal and proximal tibial vessels on this side is reduced, resulting in reduced opacification of the vessels.

A.7 As this patient has rest pain, revascularization should be undertaken, assuming his co-morbidities do not preclude intervention.

Approximately 30–60% of patients with disabling claudication or critical limb ischaemia (see Revision points) are suitable for percutaneous intervention (angioplasty, stent, thrombolysis or combinations of these techniques).

Many patients require bypass surgery, either owing to the length of the stenotic lesion/occlusion or as a result of the quality of the vessels above and below the lesion.

Revision Points

Chronic Lower Limb Ischaemia

Incidence

Approximately 5 : 1000 population/year in developed countries.

Aetiology

• Atherosclerosis (>90% of cases).

• Thromboangitis obliterans (Buerger’s disease).

• Vasculitis.

• Arterial trauma.

• Rare causes: cystic adventitial disease of the popliteal artery, popliteal artery entrapment.

Differential Diagnoses

• Spinal canal disease.

• Sciatica.

• Peripheral neuropathy.

Note: presence of pulses, ankle–branchial index (ABI) or exercise ABI should allow differentiation between claudication and neurological cause of pain.

Risk Factors for Atherosclerosis

Classification

See Table 23.1.

Table 23.1 Classification of lower limb ischaemia

Classification	Doppler Ankle–Brachial Index (ABI) Approximate	Fontaine Stage
Claudication

0.6–0.9 II

Critical limb ischaemia:

• rest pain

• ulceration and/or gangrene

0.3–0.6 III <0.4 IV

Issues to Consider

• How successful are conservative measures in the prevention of progression of occlusive vascular disease?

• What is neurogenic claudication and how does it differ from vascular claudication?

• What measures may help this man give up smoking?

Further Information

, www.scvir.org. Home page of the American Society of Cardiovascular and Interventional Radiology. Interesting information and links about peripheral vascular diseases and the role of endovascular therapies

Norgen L, Hiatt WR, Dormandy JA, et al. Inter-Society Consensus for the Management of Peripheral Arterial Disease (TASC II), TASC II Working Group. Journal of Vascular Surgery, 45. 2007: S1-S67.