Chronic lower limb Ischaemia
Symptoms
On exercise, patients complain of a severe cramp, usually in the calf, which resolves when they stop walking. They may be unable to continue walking with the pain and often the symptoms are worse walking uphill but never occur at rest. This is called intermittent claudication. Patients may experience similar pain in buttocks and thighs associated with male impotence, the ‘Leriche syndrome’. Claudication can occur in both legs but is often worse in one leg.
Rest pain is defined as a severe unremitting pain in the foot, which stops a patient from sleeping. It is partially relieved by dangling the foot over the edge of the bed or standing on a cold floor. Patients with severe PVD or critical lower limb ischaemia may have ulceration or necrosis of the tissue (gangrene).
Signs
The lower limbs are cold with dry skin and lack of hair. Pulses may be diminished or absent. Ulceration may occur in association with dark discoloration of the toes or gangrene.
Risk factors
Common risk factors are:
■ smoking
■ diabetes
■ hypercholesterolaemia
■ hypertension.
Premature atherosclerosis in patients aged < 45 years may be associated with thrombophilia and hyperhomocysteinaemia.
Differential diagnosis
Symptoms may be confused with those of:
■ spinal canal claudication (but all pulses are present)
■ osteoarthritis hip/knee (knee pain often at rest)
■ peripheral neuropathy (associated with numbness and tingling)
■ popliteal artery entrapment (young patients who may have normal pulses)
■ venous claudication (bursting pain on walking with a previous history of a DVT)
■ fibromuscular dysplasia
■ ‘Buerger’s’ disease (young males, heavy smokers).
Investigations
An estimation of the anatomical level of disease may be possible with the examination of pulses. The severity of disease is indicated by ankle/brachial pressure index (ABPI). This is a measurement of the cuff pressure at which blood flow is detectable by Doppler in the posterior tibial or anterior tibial arteries compared to the brachial artery (ankle/brachial pressure). Intermittent claudication is associated with an ABPI of 0.4–0.9. Values of < 0.4 are associated with critical limb ischaemia. The sensitivity of the test may be improved by a fall in ABPI after exercise. If the arteries are heavily calcified and incompressible, i.e. in renal or diabetic disease, the ABPI will be falsely elevated. In these patients toe pressure values are more sensitive.
Diagnostic angiograms are now performed less commonly as Doppler and duplex imaging give an accurate anatomical assessment of the level and degree of disease. Angiograms are performed via a percutaneous arterial catheter and allow therapeutic interventions to be performed Magnetic resonance and CT angiography are not routinely performed.
Management
Medical
All patients with peripheral vascular disease need aggressive risk factor management. Patients are encouraged to stop smoking and need smoking cessation advice. Patients with diabetes mellitus need regular chiropody care and diabetic management. Hypercholesterolaemia should be treated as this reduces disease progression. It has been shown by the Heart Protection Study that even the reduction of a normal cholesterol level reduces mortality from cardiovascular disease. Low-dose aspirin reduces the risk of myocardial infarction and stroke in patients with peripheral vascular disease. There are as yet no proven oral medications that are of benefit in patients with claudication. Supervised exercise programmes significantly improve walking distance and quality of life.
Surgical/radiological
These are only considered in patients who have had their risk factors addressed and who feel that their lifestyle is disabled by their symptoms. For instance a person who can only walk 50 yards before claudicating but who also has severe breathing problems may never need lower limb intervention.
Percutaneous transluminal angioplasty is the first option and is carried out via a catheter inserted into the femoral artery. The long-term patency rates decrease as the angioplasty becomes more distal. The long-term results of angioplasty appear to be similar to those of a continued exercise programme. Arterial stents may be deployed in recurrent iliac disease, and drug-eluting stents allowing long-term patency are being used, e.g. paclitaxel.
Bypass procedures may be performed using Dacron, polytetrafluroethylene (PTFE) or autologous veins. Bypasses to distal vessels have poorer long-term patencies. Prosthetic grafts have equal patencies in above-knee bypasses but are inferior to veins below the knee.
In severe ischaemia with unreconstructable arterial disease an amputation may be necessary. An amputation may lead to loss of independence, with only 70% of belowknee and 30% of above-knee amputees achieving full mobility.
Symptoms
On exercise, patients complain of a severe cramp, usually in the calf, which resolves when they stop walking. They may be unable to continue walking with the pain and often the symptoms are worse walking uphill but never occur at rest. This is called intermittent claudication. Patients may experience similar pain in buttocks and thighs associated with male impotence, the ‘Leriche syndrome’. Claudication can occur in both legs but is often worse in one leg.
Rest pain is defined as a severe unremitting pain in the foot, which stops a patient from sleeping. It is partially relieved by dangling the foot over the edge of the bed or standing on a cold floor. Patients with severe PVD or critical lower limb ischaemia may have ulceration or necrosis of the tissue (gangrene).
Signs
The lower limbs are cold with dry skin and lack of hair. Pulses may be diminished or absent. Ulceration may occur in association with dark discoloration of the toes or gangrene.
Risk factors
Common risk factors are:
■ smoking
■ diabetes
■ hypercholesterolaemia
■ hypertension.
Premature atherosclerosis in patients aged < 45 years may be associated with thrombophilia and hyperhomocysteinaemia.
Differential diagnosis
Symptoms may be confused with those of:
■ spinal canal claudication (but all pulses are present)
■ osteoarthritis hip/knee (knee pain often at rest)
■ peripheral neuropathy (associated with numbness and tingling)
■ popliteal artery entrapment (young patients who may have normal pulses)
■ venous claudication (bursting pain on walking with a previous history of a DVT)
■ fibromuscular dysplasia
■ ‘Buerger’s’ disease (young males, heavy smokers).
Investigations
An estimation of the anatomical level of disease may be possible with the examination of pulses. The severity of disease is indicated by ankle/brachial pressure index (ABPI). This is a measurement of the cuff pressure at which blood flow is detectable by Doppler in the posterior tibial or anterior tibial arteries compared to the brachial artery (ankle/brachial pressure). Intermittent claudication is associated with an ABPI of 0.4–0.9. Values of < 0.4 are associated with critical limb ischaemia. The sensitivity of the test may be improved by a fall in ABPI after exercise. If the arteries are heavily calcified and incompressible, i.e. in renal or diabetic disease, the ABPI will be falsely elevated. In these patients toe pressure values are more sensitive.
Diagnostic angiograms are now performed less commonly as Doppler and duplex imaging give an accurate anatomical assessment of the level and degree of disease. Angiograms are performed via a percutaneous arterial catheter and allow therapeutic interventions to be performed Magnetic resonance and CT angiography are not routinely performed.
Management
Medical
All patients with peripheral vascular disease need aggressive risk factor management. Patients are encouraged to stop smoking and need smoking cessation advice. Patients with diabetes mellitus need regular chiropody care and diabetic management. Hypercholesterolaemia should be treated as this reduces disease progression. It has been shown by the Heart Protection Study that even the reduction of a normal cholesterol level reduces mortality from cardiovascular disease. Low-dose aspirin reduces the risk of myocardial infarction and stroke in patients with peripheral vascular disease. There are as yet no proven oral medications that are of benefit in patients with claudication. Supervised exercise programmes significantly improve walking distance and quality of life.
Surgical/radiological
These are only considered in patients who have had their risk factors addressed and who feel that their lifestyle is disabled by their symptoms. For instance a person who can only walk 50 yards before claudicating but who also has severe breathing problems may never need lower limb intervention.
Percutaneous transluminal angioplasty is the first option and is carried out via a catheter inserted into the femoral artery. The long-term patency rates decrease as the angioplasty becomes more distal. The long-term results of angioplasty appear to be similar to those of a continued exercise programme. Arterial stents may be deployed in recurrent iliac disease, and drug-eluting stents allowing long-term patency are being used, e.g. paclitaxel.
Bypass procedures may be performed using Dacron, polytetrafluroethylene (PTFE) or autologous veins. Bypasses to distal vessels have poorer long-term patencies. Prosthetic grafts have equal patencies in above-knee bypasses but are inferior to veins below the knee.
In severe ischaemia with unreconstructable arterial disease an amputation may be necessary. An amputation may lead to loss of independence, with only 70% of belowknee and 30% of above-knee amputees achieving full mobility.