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Lower Extremity PAD

Also called: Lower Extremity Peripheral Arterial Disease, PAD of the Lower Extremities

- Summary
- About lower extremity PAD
- Signs and symptoms
- Diagnosis methods
- Treatment options
- Exercise and medical therapy
- Endovascular procedures
- Surgical procedures
- Questions for your doctor

Reviewed By:
Kerry Prewitt, M.D., FACC
George A. Petrossian, M.D., FACC

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Diagnosis methods for lower extremity PAD

The diagnosis for PAD typically begins with a medical history and physical examination. However, because the condition is highly variable, some studies have found that relying on traditional symptoms to diagnose PAD can result in many missed cases. The characteristic leg pain (intermittent claudication) may appear almost anywhere in the leg, and its intensity varies depending on the severity of the blockage and the duration of the exercise. PAD can also be asymptomatic (without symptoms).

To diagnose PAD, physicians usually rely on a painless, noninvasive test called the ankle-brachial index (ABI). The ABI compares the blood pressure in the leg to the blood pressure in the arm. Normal leg blood pressure should be anywhere from 90 to 110 percent of the blood pressure measured in the arm and abnormalities in this ratio may indicate PAD. By taking the blood pressure at several locations along the length of the leg, the physician can often determine the presence and location of blockage in any leg blood vessels (e.g. iliac, femoral, or tibial).

The ABI involves the use of a Doppler transducer (a small ultrasound device) to hear the blood flow and a blood pressure cuff sphygmomanometer. First, blood pressure in the arm is measured. Then blood pressure of the leg is measured. If the ABI is less than 0.9 (in other words, 90 percent of arm blood pressure) there is usually diminished blood flow to the leg. Values below 0.5 are often associated with severe disease. If the ABI is normal, but the physician still suspects PAD, the patient may be asked to exercise briefly to elevate the blood flow before the test is conducted.

Other tests that may be used to diagnose PAD of the lower extremities include:

Plethysmograms and Doppler studies. These are tests that determine how effective the pulse wave is transmitted to the leg. These tests are painless and non-invasive. They are usually performed in a “vascular laboratory,” which is a facility dedicated to the non-invasive diagnosis of vascular conditions.

At one time, plethysmograms were used frequently in the diagnosis of lower extremity PAD. However, this test has largely been replaced by more advanced imaging tests, such as the Doppler ultrasound. Duplex (or Doppler) imaging is useful in examining specific areas in the leg arteries but does not play the central role in diagnosis that it does for carotid disease artery. It is also painless and noninvasive.
Magnetic resonance angiography (MRA) on the legs. This test uses magnets to produce images of the arteries and veins with similar accuracy to invasive angiograms but without puncturing the artery to inject dye. MRA is also used to identify small arteries in the lower leg that cannot be seen or detected with angiograms or other testing methods. It is usually performed if some form of intervention, such as surgery, angioplasty, stenting or atherectomy, is considered.
Angiogram of the lower extremities. A test in which a dye is injected into the arteries through a small catheter and x-ray images are taken of the vessels. This is still the best way to evaluate the arteries of the legs since it quickly shows all of the arteries and the collateral pathways that have developed.