PERIPHERAL ARTERIAL DISEASE EXAMINED

From: The Clinical Services Journal

January 2010
Dr ROBERT MORGAN, consultant vascular and interventional radiologist at St George’s Vascular Unit, provides an overview of the burden of PAD, guidance on how to diagnose the condition, relevant risk factors, risk-factor modification and treatment options available.

Today, one in five in the 65 to 75-year-old age group in the UK1 has peripheral arterial disease (PAD), also known as peripheral vascular disease, on clinical examination. Healthcare professionals have a significant role to play in preventing the escalation of this disease by ensuring early diagnosis, providing patients with advice on risk-factor modification and managing patients with an appropriate treatment. Although prevalence of PAD in primary care practices is high, it is commonly under-diagnosed. This is due to many doctors not obtaining a relevant history for PAD and frequently overlooking subtle signs of the condition on physical examination.2

What are the symptoms?

Today, only a quarter of the one in five 65 to 75-year-olds have any symptoms at all. The “silent” nature of this condition, along with the overall increasing age of the population and the escalating incidence of risk factors for PAD, lead to concern that PAD may become one of the leading diseases of this century. One of the more common indicators of PAD is extreme leg pain caused by walking or exercising, as many as 40% of people with PAD never complain of this symptom2 – and those who do often mistake the discomfort for ageing pains and fail to seek treatment, allowing the condition to worsen. PAD is highly treatable in its early stages, but as the disease remains undiagnosed, the likelihood of facing complications greatly increases, as does the probability of suffering from a heart attack or stroke. Symptoms to look for and discuss with patients when making a diagnosis of PAD include:

• Fatigue or cramping in the leg muscles (claudication) when walking.
• Pain in the legs and/or feet that disturbs sleep.
• Ischaemic tissue ulceration (punched-out, painful, with little bleeding), gangrene.
• Pallor with leg elevation after one minute at 60 degrees (normal colour should return in 10 to 15 seconds; longer than 40 seconds indicates severe ischaemia).
• Absent or diminished femoral or pedal pulses (especially after exercising the limb).
• A lower temperature in one leg compared to the other
• Hair loss and/or poor nail growth (brittle nails).
• Dry, scaly, atrophic skin.

What is the cause?

The underlying cause of PAD is atherosclerosis – a common, progressive disease that involves the hardening and narrowing of the arteries. This is a result of fat, cholesterol and other substances building up in the walls of arteries and forming plaque (atheroma or fatty deposits). As the plaque deposits intensify, the arteries narrow and become less flexible, restricting blood flow. Narrowing of the coronary arteries due to atherosclerosis can result in angina, shortness of breath, heart attack and other symptoms. In PAD, the lower extremities are affected. When blood flow to the legs becomes limited or restricted, the propensity for developing infections, chronic foot ulcers, gangrene and leg lesions dramatically increases. In severe cases, amputation of the affected limb is required if other available treatments fail.

Risk factors

The most common risk factors for PAD include: diabetes, high blood pressure, high cholesterol levels, obesity, smoking and being older than 50.3 All of which are also risk factors for cardiovascular disease. People with diabetes are at the greatest risk for developing severe PAD and experiencing complications from the disease. In fact, people with diabetes are up to fifteen times more likely to endure lower-limb amputation than those without diabetes and problems with the feet are one of the most common causes of diabetes-related hospitalisation.4

Simple test for PAD

General practitioners can quickly and easily test for PAD. The most common test is the ankle/brachial pressure index (ABPI) at rest, a non-invasive process that compares blood pressure in the ankles with the blood pressure in the arms. Although an ABPI can help determine if someone has PAD, it cannot identify the location and degree of the obstruction in the artery. The non-invasive “Doppler Test” is also available and checks a specific artery for blockage. The test uses ultrasound waves to measure blood flow in arteries within the lower extremities. A physical examination and listening to the heart and lungs with a stethoscope will help detect early atherosclerosis. In patients with PAD, a whooshing or blowing sound (“bruit”) is heard over an artery. In complicated or difficult to diagnoses cases, patients should be referred to secondary care where other tests may be carried out to diagnose atherosclerosis or complications. These tests include:

• Arteriography.
• Cardiac stress testing.
• CT scan.
• Intravascular ultrasound (IVUS).
• Magnetic resonance arteriography (MRA).

Managing PAD in primary care

Non-surgical therapy for intermittent claudication involves risk-factor modification, exercise and pharmacological therapy. Details on each of these can be found below.

• Dietary modification, including eating a low-fat, low-cholesterol, and low-salt diet.
• Weight reduction if the patient is overweight.
• Stop smoking. There is a higher correlation between smoking and developing PAD than any other risk factor. All available strategies to help patients quit smoking, such as counselling and nicotine replacement, should be used. Stopping smoking reduces the severity of claudication, the progression of disease and the risk of heart attack and death from vascular causes. Studies have demonstrated lower rates of amputation in patients who stop smoking.5
• Hypertension is a significant risk factor for PAD. Antihypertensives should be prescribed to patients with PAD to reduce morbidity from cardiovascular and cerebrovascular disease.
• Diabetes. Controlling blood sugar levels could not only decrease the incidence of cardiovascular disease and heart attack, but also reduce the occurrence of PAD and PAD outcomes (claudication, peripheral revascularisation, or critical limb ischaemia and amputation).6
• Hyperlipidemia. Studies have demonstrated the benefits of lipidlowering therapy in patients with PAD. Controlling lipids has been shown to reduce disease progression and the severity of claudication.7
• Exercise. PAD can be effectively treated with a formal exercise programme. Research has shown that the greatest improvements in walking ability occur when the following occur: each exercise session is continued for more than 30 minutes, at least three sessions are undertaken per week, the patient walks until near-maximal pain is reached and the exercise regime is continued for at least six months.8
• Pharmacological therapy. Effective drug therapies for PAD include aspirin (with or without dipyridamole), clopidogrel, cilostazol and pentoxifylline. Aspirin and dipyridamole increase the pain-free walking distance and blood flow.9


Management in secondary care

In patients with severe PAD whose condition is not improving with riskfactor modification, exercise programmes and pharmacological therapy, invasive procedures may need to be carried out in the hospital setting. These procedures include angioplasty, stenting or surgery. Angioplasty is a non-surgical procedure that is used to widen arteries. During this procedure, a catheter with a balloon on its tip is inserted into the narrowed artery and inflated. Once the artery widens, the balloon is deflated and the catheter is withdrawn, often restoring blood flow. Until recently, there was uncertainty around the efficacy of angioplasty in combination with supervised exercise and best pharmacological therapy in the treatment of intermittent claudication. A recent study demonstrated that angioplasty in combination with exercise and pharmacological therapy improved walking distances and ABPI 24 months after the procedure compared with exercise and drug therapy alone in patients with stable mild to moderate intermittent claudication.10 Stenting can also be performed to help widen arteries. The stent is inserted into the artery, where it is expanded to hold the artery open and allow blood flow to resume. The procedure is minimally invasive, as the stent is guided into the restricted artery with a catheter that is inserted through a small opening in the artery. Drug-eluting stents have been developed to prevent plaque from growing around the stent due to inflammation and forming scar tissue (restenosis). In patients where large sections of an artery are narrowed, arterial bypass surgery may be required. Bypass surgery is usually successful, but can be risky for patients who suffer from co-morbidities such as diabetes or high blood pressure. With increased awareness of PAD among both patients and healthcare professionals, and proactive testing in primary care for those at risk, we can hope to reduce the significant burden PAD may place on the health system and prevent it from becoming a leading cause of hospitalisation during this century.

References

1 Fowkes F.G.R., Housley E., Cawood E.H.H., MacIntyre C.A.A., Ruckley C.V., Prescott R.J. Edinburgh artery study: prevalence of asymptomatic and symptomatic peripheral arterial disease in the general population. Int J Epidemiol 1991;20:384-91. 2 Hirsch A.T. et al. Peripheral arterial disease, detection, awareness, and treatment in primary care. JAMA 2001;286:1317-24. 3 PAD Risk Factors and Possible Complications. American Heart Association. www.americanheart.org/ presenter.jhtml?identifier=3020256 (accessed Jan 09). 4 von Wartburg L. Diabetes Health: “The Double Whammy: When Peripheral Artery Disease Complicates Peripheral Neuropathy” May 8, 2007. www.diabeteshealth.com/read/2007/ 05/08/5175.html (accessed Jan 09). 5 Girolami B. et al. Treatment of intermittent claudication with physical training, smoking cessation, pentoxifylline, or nafronyl: a meta- analysis. Arch Intern Med 1999;159:337-45. 6 Adler A.I. et al. UKPDS 59: Hyperglycemia and Other Potentially Modifiable Risk Factors for Peripheral Vascular Disease in Type 2 Diabetes. Diabetes Care 2002;25:894-99. 7 LaRosa J.C., He J., Vupputuri S. Effect of statins on risk of coronary disease: a meta-analysis of randomized controlled trials. JAMA 1999;282:2340-6. 8 Stewart K.J. et al. Exercise training for claudication. N Engl J Med 2002;347:1941-51. 9 Regensteiner J.G., Hiatt W.R. Current medical therapies for patients with peripheral arterial disease: a critical review. Am J Med 2002;112:49-57. 10Greenhalgh R.M. et al. The adjuvant benefit of angioplasty in patients with mild to moderate intermittent claudication (MIMIC) managed by supervised exercise, smoking cessation advice and best medical therapy: results from two randomised trials for stenotic femoropopliteal and aortoiliac arterial disease. Eur J Vasc Endovasc Surg. 2008 Dec;36(6):680-8.