Cardiovascular

Peril on Periphery

Peripheral arterial disease (PAD) is marked by gradual narrowing of the arteries or occlusions in the aorta and its branches (except the coronary arteries). Such arterial blockages can cause stroke, renal problems, and circulatory problems in the legs. With more advanced disease, resting pain and subsequent tissue loss ensue.

In most cases, PAD results from and indicates systemic atherosclerosis. It causes functional disability, a diminished quality of life, and a dramatically higher risk of cardiovascular disease and death. It also raises the risk of myocardial infarction (MI) fivefold and the risk of stroke two- to threefold.

Approximately 8 to 12 million Americans have PAD, but because of its often subtle development and manifestations, it’s commonly underdiagnosed and undertreated. Incidence increases with age. PAD occurs in up to 20% of persons older than age 70.

Yet despite its high prevalence and strong link to cardiovascular mortality, PAD gets relatively little attention. Commonly it’s overlooked by primary care providers or mistaken for arthritis or aging—until symptoms become severe enough to warrant investigation. Not surprisingly, one in five people with the main symptom of PAD—claudication (pain and cramps in the lower leg)—say they haven’t been diagnosed and aren’t getting treatment. Although early recognition and detection are critical to slowing or halting disease progression, only about 25% of persons with PAD get adequate treatment.

Signs and symptoms

Signs and symptoms of PAD result from gradual reduction of blood flow through affected arteries in the involved extremity or organs. Just under half of persons with PAD experience claudication with activity. The remainder are asymptomatic or have mild symptoms that they may chalk up to normal aging.

Claudication results from poor blood flow and inadequate oxygen to the muscles. It usually eases after a short rest period but recurs when activity resumes. Patients typically describe it as a heavy sensation; an aching, burning, or cramping; or a feeling of fatigue. Typically, it affects the calf muscles but also can occur in the thighs or buttocks, depending on the site of the stenosis.


Some persons with PAD also develop critical limb ischemia (CLI)—a severe, sometimes complete obstruction in an artery that reduces or even eliminates blood flow. CLI causes extreme pain; without prompt revascularization, it may lead to loss of the affected limb. CLI portends a far worse outcome than PAD alone. The 1-year mortality rate is 25%; the 1-year amputation rate, 30%.

Evaluation

During your assessment of a patient with possible PAD, stay alert for the 5 “P’s”—pain, pallor, pulselessness (decreased or absent pulses), paralysis, and paresthesia. When examining the legs, ask yourself:

  • Is the skin over the extremity a normal color?
  • Is the extremity warm?
  • Are sensation and movement adequate?
  • Is the limb shiny and hairless?
  • Is edema present?
  • Are the pulses palpable, or is a Doppler device needed to detect them? If they’re palpable, how strong are they?

Duplex ultrasound of the extremities helps determine the location and degree of stenosis. Using two forms of ultrasound, this test allows visualization of the arterial structure and shows how well blood flows through the vessels. It can measure the speed of blood flow and estimate arterial diameter as well as the degree of obstruction. To confirm PAD, expect the physician to order an ankle brachial index. (See Ankle brachial index.)

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Treatment

The earlier treatment begins, the better the hope of delaying devastating complications. Even in patients with advanced PAD that requires surgery or other invasive interventions, optimal medical management improves outcomes, extends the success of interventions, improves functional ability, and prolongs life. Treatment options may include risk-factor modification, medications, and surgery. (See Treatment recommendations for PAD.)

Successful long-term treatment requires a comprehensive therapeutic plan aimed at delaying disease progression, reducing cardiovascular ischemic events, prolonging limb life, and maintaining or improving functional ability. Aggressive risk-factor modification and pharmacologic interventions may promote regression of PAD and its symptoms.

Risk-factor modification

Risk-factor modification is the first line of treatment. Helping your patient gain control over the disease can reduce claudication, increase exercise tolerance, and promote a more active lifestyle.

The patient should actively participate in the risk-factor modification plan as appropriate—for instance, by helping to formulate a smoking cessation plan, starting an exercise program, making dietary changes to lose or maintain weight, and controlling high blood pressure and cholesterol.

If medications are prescribed to help control risk factors, teach your patient how they work, how to take them, and possible adverse effects. Emphasize that their benefits can make it easier for the patient to comply with other required behavioral modifications.

Smoking cessation. This is the most important intervention in slowing atherosclerosis progression. Patients with PAD are likely to have coexisting cardiac and/or cerebrovascular disease, further raising their risk of MI and stroke. Those who keep smoking have a 5-year mortality rate of 40% to 50%. Make sure patients understand that continuing to smoke will shorten their lives dramatically. Stress that all tobacco forms can damage the vascular endothelium, promote coagulation, and accelerate atherosclerosis progression. Explain that smoking will contribute to failure of limb revascularization procedures and significantly increase the chance that amputation will be needed. Emphasize the importance of planning a date for smoking cessation, and discuss various methods to help the patient quit smoking.

Exercise. Exercise is an important part of PAD management. A supervised program brings the greatest benefit. Reassure the patient that claudication doesn’t damage the legs; if appropriate, instruct her to walk to the point of experiencing claudication, take a short rest until the pain resolves, and then resume walking. Explain that despite the pain, walking can improve physical functioning and ultimately reduce claudication. Urge her to walk a bit longer each day. Mention that over time, progressive exercise significantly increases the distance she’ll be able to walk without pain. Inform her that regular exercise also promotes weight loss, lowers blood pressure, increases levels of high-density lipoprotein (the “good” cholesterol), and tones the cardiovascular system. It also may promote collateral circulation, bringing more oxygen and nutrient-rich blood to the muscles and reducing claudication.

Dietary changes. Working with a dietitian can help your patient enjoy a proper diet—one that’s low in animal fats and rich in fruits and vegetables. Such a diet slows PAD development and reduces the risk of MI and stroke. Eating a high-fiber, low-fat, low-cholesterol diet is always good advice, especially for those battling diabetes, excess weight, and high cholesterol. Reducing saturated-fat intake helps lower cholesterol levels more than any other dietary change. Eliminating cholesterol-rich food also helps reduce cholesterol levels.

Controlling diabetes, hypertension, and dyslipidemia. Diabetes,
hypertension, and dyslipidemia increase the risk of PAD sixfold. Pa­tients with coexisting diabetes and PAD are at extremely high risk for cardiovascular events and should be treated aggressively to optimize glycosylated hemoglobin levels. The abnormal metabolic state that occurs in diabetes causes vascular dysfunction. Chronic hyperglycemia, insulin resistance, and dyslipidemia put arteries at increased risk for atherosclerosis, resulting in vasoconstriction, inflammation, and a propensity for thrombosis.

Hypertension accelerates atherosclerosis development by initiating arterial wall thickening and vasoconstriction. This leads to dysfunction of the endothelium and a cascade of events that increases the PAD risk 2.5 times for men and nearly four times for women. The Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure recommends keeping blood pressure as close to 120/80 mm Hg as possible and aggressively treating higher pressures, especially in patients with renal disease or diabetes.

Dyslipidemia also must be addressed. In PAD, high levels of circulating lipids irritate the vessels’ endothelial walls. Continued endo­thelial injury directly results in development of atherosclerotic lesions. Lifestyle changes and lipid-lowering drugs can slow this process.

Antiplatelet therapy

Antiplatelet therapy plays a central role in slowing atherosclerosis. In atherosclerosis, platelets aggregate, forming clots that severely narrow the arterial diameter and slow blood flow. Antiplatelet drugs (such as aspirin and clopidogrel [Plavix]) prevent platelets from sticking together, keeping them slippery and helping to decrease clot formation.

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Invasive treatments

Invasive treatments may be necessary for patients with extensive vascular disease. Angiography offers both diagnostic and interventional value. In some cases, an interventional radiologist can insert a flexible wire into the vascular system to find a narrowed or blocked artery, and open it with angioplasty (possibly with a stent) or atherectomy (in which a cutting balloon is placed in the area of the lesion and plaque is shaved off the artery wall). These procedures require minimal sedation and a short recovery time.

Surgery (such as arterial bypass grafting and endarterectomy) may be warranted for patients at risk for losing a limb or when revascularization by angiography isn’t an option.

Put PAD on your radar screen

Many healthcare providers remain unaware of the magnitude of PAD and don’t know how best to detect and manage it. As a nurse, you’re in an excellent position to assess and intervene for PAD and educate patients at high risk. Patient education, risk-factor management, and self-care strategies are key components you can use to help patients understand and manage this disease.

Selected references

Ekers M, Hirsch A. Vascular medicine and peripheral arterial disease rehabilitation. In Fahey V, ed. Vascular Nursing. 4th ed. St. Louis, MO: Saunders; 2004:187-213.

Hirsh A, Criqui M, Treat-Jacobson D, et al. Peripheral arterial disease detection, awareness and treatment in primary care. JAMA. 2001;286(11):1317-1324.

Mannava K, Money S. Current management of peripheral arterial occlusive disease: a review of pharmacologic agents and other interventions. Am J Cardiovasc Drugs. 2007; 7(1):59-66.

Sieggreen M. Contemporary approach to peripheral arterial disease. Nurse Pract. 2006;31(7):15-25.


When Cindy Johnson wrote this article, she was the Vascular Service Program Coordinator at Samaritan Health Services in Corvallis, Oregon. Currently she is the Heart Function Clinic Navigator for the Medical Specialties Clinic at Red Deer Regional Hospital Centre in Red Deer, Alberta, Canada.

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