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February 2009

Peripheral Artery Disease Under Diagnosed, Under Treated

Michael S. Conte, M.D.
Chief of Vascular and Endovascular Surgery
UCSF Heart and Vascular Center

The epidemiology of peripheral artery disease (PAD) — a common manifestation of atherosclerosis — is growing due to aging of the population and the burden of risk factors, especially the increasing prevalence of diabetes. Key risk factors include smoking, diabetes, hypertension and dyslipidemia. There also is a racial disparity. Non-Hispanic blacks have a higher prevalence of PAD that is not explained by other risk factors. About one out of three diabetics over the age of 50 has PAD. And up to 70 percent of all non-traumatic limb amputations are performed on diabetics with severe PAD.

PAD results from atherosclerosis of the large peripheral arteries, which causes acute or chronic ischemia to the arms, stomach, head, kidneys and most commonly to the lower extremities. The condition is highly associated with atherosclerosis in other parts of the body such as the brain and heart, making PAD patients at increased risk for stroke, heart attack and cardiovascular death.

While PAD is extremely common among older persons, diabetics and smokers and has serious, life-threatening consequences, it is often under diagnosed and under treated. Regular screening for PAD and early diagnosis are critical to preventing vascular disease and saving limbs from amputation.

Without aggressive and timely interventions, patients with advanced, non-responsive PAD may progress to lose a limb or suffer from pain, non-healing wounds and diminished quality of life.

Symptoms

Many patients with early PAD have mild or no symptoms. About one in 10 patients experiences intermittent claudication, or pain in the limb with ambulation. Patients with claudication may experience functional disability but are usually not at imminent risk for loss of the limb.

The more advanced stage of PAD is critical limb ischemia (CLI), where blood flow to the extremity is severely impaired and the risk for amputation is high if untreated. Although only between 1 to 3 percent of patients with PAD have CLI at presentation, the risk of progression to CLI is three to five fold higher for diabetics and smokers. All patients with PAD should be monitored for signs of deterioration.

Common PAD symptoms may include:

  • Change in the color of the feet or toes
  • Changes in the toenails
  • Coldness in the lower leg or foot, especially when compared with the other leg
  • Hair loss on the feet and legs
  • Painful cramping in the hip, thigh or calf muscles after walking or climbing stairs (claudication)
  • Sores on the toes, feet or legs that heal slowly

Signs and symptoms of CLI include:

  • Pain at rest in the feet or toes, particularly at night
  • Non-healing wounds
  • Gangrenous changes on the toes or foot
  • Absence of pulses, dependent rubor, in association with the above

Screening

Primary care physicians play a critical role in diagnosing and monitoring PAD. Patients with significant risk factors for PAD should be screened regularly. Those risk factors are age 55 and older; those who smoke, have diabetes, hypertension, dyslipidemia and chronic renal disease; or those with other established atherosclerotic cardiovascular diseases, cardiac or cerebral including those who are asymptomatic.

Clinical evidence strongly suggests that once a diagnosis of PAD is made, a patient's risk of limb loss, heart attack and stroke significantly increases. Patients with PAD should be promptly referred to a vascular specialist.

Physical Exam

At-risk patients should undergo regular and thorough physical exams by their primary care physician, focusing on the lower extremities, assessing presence and quality of pulses, trophic changes, changes in skin color and evidence of poor wound healing.

Ankle-brachial Index

Measurement of a patient's ankle-brachial index (ABI) is a simple means of identifying PAD and correlates strongly with risk. The ABI is the ratio of the systolic pressure of the posterior tibial (PT) and dorsalis pedis (DP) arteries to the higher of the brachial pressures in either arm.

The ABI is easily performed in the office with a sphygmomanometer cuff and hand-held Doppler instrument. Typically the higher of the two ankle pressures (PT or DP) is used to define the ABI for the limb. The typical cut-off point used to define PAD is an ABI < 0.90 at rest.

Other Tests

Duplex ultrasound, computed tomography (CT) angiography and magnetic resonance (MR) angiography may be indicated to define the location and severity of arterial blockages for symptomatic patients. Blood tests to measure a patient's lipid panel and homocysteine and C-reactive proteins also may be recommended.

Treatment

PAD is a chronic disease and the nature of its progression is unpredictable. It is critical that primary care physicians and vascular specialists work together to develop a longitudinal, aggressive treatment plan. It is important to recognize that PAD may be the initial manifestation of atherosclerosis in many patients. A comprehensive management plan is needed to reduce the global risk of cardiovascular events.

Treatment for the limb depends on the severity of PAD. Many patients can be managed with non-invasive therapies such as lifestyle changes, medication, or both.In advanced cases, surgical or percutaneous interventions may be necessary. Patients with known or suspected PAD should be referred to a vascular specialist for comprehensive assessment and surveillance.

Modification of Risk Factors

  • Blood pressure management
  • Cholesterol medication
  • Diabetes control
  • Diet low in saturated fats
  • Physical activity (walking program)
  • Smoking cessation

Drug Therapy

  • ACE inhibitors
  • Antiplatelet therapy such as aspirin or clopidigrel
  • Cholesterol-lowering statins, including simvastatin, atorvastatin, rosuvastatin or pravastatin
  • Medications that may assist with walking, cilostazol or pentoxifylline

Surgical- or Catheter-based Interventions

Patients who experience no improvement with lifestyle change and drug therapy, or who have progression of the disease, may require endovascular or surgical intervention, including angioplasty, bypass surgery and stenting. Surgical intervention is recommended based on the size and location of the blockage, the patient's overall medical condition and level of function.

UCSF Heart and Vascular Center

UCSF brings together cardiologists, cardiac and vascular surgeons, interventional radiologists and other specialists to provide the most advanced and effective treatments, many of them developed at UCSF, for PAD and other vascular conditions.

Our experts are at the forefront of researching heart and vascular conditions and developing new treatments. We have authored dozens of papers studying the outcomes of advanced surgical procedures and novel drugs in the treatment of PAD.

For more information, contact the Physician Referral Service at UCSF Medical Center:

Phone (888) 689-UCSF or (888) 689-8273
Email referral.center@ucsfmedctr.org

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