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Peripheral artery disease and intermittent claudication

Description

An in-depth report on the causes, diagnosis, and treatment of peripheral artery disease.

Alternative Names

Peripheral arterial disease; PAD; Peripheral vascular disease;

Diagnosis

PAD is greatly under diagnosed. Many patients do not report symptoms, or may not even have symptoms. People should be checked for peripheral artery disease if they have risk factors for heart disease, leg pain during walking, or ulcers on their legs.

Physical Examination

The doctor should perform a number of physical examinations to check for high blood pressure, heart abnormalities, blockage(s) in the artery in the neck, and abdominal aneurysms. The doctor should also examine the skin of the legs and feet for color changes, ulcers, infection, or injuries, and check the pulse of the arteries in the leg.

Doppler Ultrasound and Ankle-Brachial Index

Intermittent claudication caused by peripheral artery disease is typically diagnosed using a procedure called Doppler ultrasound and a calculation called the ankle-brachial index. This method is also proving to be a helpful way to diagnose PAD in patients without symptoms of intermittent claudication.

The procedure is done as follows:

• The doctor measures the systolic blood pressure of both arms while the patient is lying down. (The systolic pressure is "top" number in a blood pressure measurement. It is the force that blood exerts on the artery walls as the heart contracts to pump out the blood. For example, in a blood pressure reading of 120/80, 120 is the systolic number.)
• The doctor then puts blood pressure cuffs on four different locations on each leg. An ultrasound probe is passed over arteries in the foot. The signal emitted from the strongest artery is recorded as the cuffs are inflated and deflated. This is the ankle's systolic pressure.

The doctor divides the systolic pressure in the ankle by that in the arm. The result is called the ankle-brachial index (ABI), also called ankle-arm pressure index (API).

What the results mean:

• ABI over 0.90 . This result often rules out PAD, but if the patient has specific risk factors for artery disease, the doctor may still suspect PAD. In such cases, the patient takes a treadmill test and another ABI measurement. If the API index drops, then the doctors makes a diagnosis of peripheral artery disease.
• ABI below 0.90 . This is usually sufficient information to diagnose PAD. The lower the index the greater the risk for heart attack, stroke, or other serious circulatory or heart events. (In patients with diabetes, the doctor may perform additional tests, which may include ultrasound, pressure measurement in the first toe, or others that might confirm or dismiss a diagnosis of PAD.)
• ABI less than 0.50. These measurements are highly associated with impaired leg function.
• ABI less than 0.40. These measurements indicate very severe blockage in the leg arteries and a risk for gangrene.

Magnetic Resonance Angiography (MAR)

MRA is a type of magnetic resonance imaging (MRI). It provides a non-invasive alternative to a traditional angiogram. The MRA uses a magnetic field and radiofrequency waves to provide pictures of arteries and blood vessels. An angiogram uses dye, which is injected through a catheter that is inserted in the groin. MRA patients are given gadolinium (a contrast material) through an IV to improve the image quality.

Computed Tomography Angiography

A new technology called computed tomography angiography (CTA) uses x-rays to visualize blood flow in arteries throughout the body. This technique is highly effective in diagnosing PAD.

Treadmill Test

A patient is often given a treadmill test if the ankle-brachial index is questionable. Patients with claudication have a 50 - 60% reduction in peak performance, which is comparable to that in patients with congestive heart failure. The treadmill test is also useful for determining the severity of the pain while walking and for assessing the effectiveness of treatments.

Waveform Analysis

A test called a wave form analysis may be used to confirm an abnormal API or pressure reading. The patient lies on his or her back for at least 10 minutes in a warm room (so that the blood vessels will not narrow). The leg is turned outward and the knee is slightly bent. The doctor passes a handheld scanner over the leg, which picks up sound waves coming from the arteries. These signals are recorded, and the wave forms are traced to detect abnormal blood flow.

Tests for Detecting Heart Disease

Patients with suspected PAD should have an electrocardiogram (ECG) and other tests that would detect heart problems. Evidence suggests that heart disease may be under diagnosed in patients with PAD. In one study, a third of patients had silent ischemia, which is heart disease without angina, the chest pain that indicates blockage of blood flow to the heart.

Ruling out Other Disorders with Similar Symptoms

A number of other tests may be ordered to rule out disorders with similar symptoms. Such disorders include:

• Arthritis
• Anemia
• Spinal stenosis -- narrowing of the spinal canal causing leg or lower back pain

• Thrombophlebitis -- blood clots in the deep veins of the legs

• Peripheral neuropathy -- nerve damage in the legs and feet, usually in people with diabetes
• Night cramps in older people that are not due to problems in blood vessels
• Muscle entrapment of the arteries or kinks in the arteries in the leg -- typically occur in young athletes
• Adventitial cystic disease -- a rare disorder that produces cysts that block the popliteal and other arteries and typically occurs in young people

• Review Date: 3/29/2007
• Reviewed By: Harvey Simon, MD, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital

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