Ankle-Brachial Index

1 What is an Ankle-Brachial Index?

The ankle-brachial index test is a fast, nonevasive way to check your risk of Peripheral Artery Disease (PAD).

Peripheral Artery disease is a condition in which the arteries in your legs or arms become narrowed or blocked.

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Individuals with PAD are at increased risk of

The ankle-brachial index test compares your blood pressure measured at your ankle to that measured at your arm. A low ankle-brachial index number can indicate narrowing or blockage of the arteries in your legs increasing your chances of circulation complications and possibly heart disease and stroke.

The ankle-brachial index test is sometimes recommended as one of a series of three tests, including the carotid ultra sound and abdominal ultrasound to look for blocked or diseased arteries.

2 Reasons for Procedure

The reasons for ankle-brachial index test is to check for Peripheral Artery Disease (PAD), this condition is characterized by narrowed arteries in your legs or arms.

Ask your doctor if you should have this test if you are aged 50 or older and if you have any of the following risk factors for PAD:

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  • being a current or former smoker
  • diabetes
  • high blood pressure
  • high blood cholesterol

If you have been already been diagnosed with PAD, your doctor may recommend having an ankle-brachial test to see if your treatment is working or otherwise.

If you have symptoms of PAD, your doctor may suggest you have an ankle-brachial index test to determine if your symptoms, such as leg pain while walking, are as a result of PAD or another condition like stenosis.

In an exercise ankle-brachial index test, you walk on a treadmill for a short time before your ankle-brachial index is measured.

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3 Potential Risks

There are no potential risks for most people who undergo ankle-brachial index.

You may feel some discomfort when the blood pressure cuffs inflate on your arm and ankle, but this discomfort is temporary and should stop when the air is released from the cuff.

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If you have serious leg or arm pain, your doctor may not recommend an ankle-brachial index test.

Instead of this test, he or she may recommend a different imaging test of the arteries in your legs.

4 Preparing for your Procedure

There are no special instructions that need to be taken note to prepare your appointment to have an ankle-brachial index test.

You may want to wear loose, comfortable clothing that allows the technician performing your test to easily place a blood pressure cuff on your ankle and upper arm.

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5 What to Expect

Read on to learn more about what to expect during and after your ankle-brachial index test.

During the test

You lie on your back and will have your blood pressure, in both arms measured by a technician using an inflatable cuff.

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Then, the technician measures blood pressure in two arteries in both your ankles using the inflatable cuff and a hand-held Doppler ultrasound device that your doctor will press on your skin.

The Doppler device uses ultrasound to produce images and lets your doctor hear your pulse in your ankle arteries after the cuff is deflated.

The procedure for performing an ankle-brachial index test may vary a little, based on your doctor's preference. Having an ankle-brachial test is painless and is similar to having your blood pressure taken during a routine visit to your doctor. You may feel some pressure taken during a routine visit to your doctor.

You may feel some pressure on your arm or ankle when the cuff inflates  to read your blood pressure.

After the test

The ankle-brachial index test should only take a few minutes, and there are no important precautions you will need following it. Your doctor will proceed to explain your results.

6 Procedure Results

After getting your ankle-brachial test results, your doctor proceeds to calculate our ankle brachial index by dividing the systolic blood pressure (top number) at the arteries near your ankle by the systolic blood pressure in the arms.

In comparison to the arm, lower blood pressure in the leg is an indication of PAD. Based on the number your doctor calculates, your ankle-brachial index may show that you have:

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  • no blockage (1 to 1.4)
  • blockage (0.9 or less)
  • rigid arteries (more than 1.4)

In this situation, you may need an ultrasound test to check for peripheral artery disease instead of an ankle-brachial index test, or a toe-brachial test, in which the blood pressures in your arm and big toe are compared. If you possess an exercise ankle-brachial index test, the ranges for the results differ.

Your doctor will explain to you what your results mean. Based on the severity of your blockage, your doctor may recommend lifestyle changes, medications or surgery to treat PAD.

The  test  may not adequately measure the ankle-brachial index if you have serious diabetes or calcified arteries with significant blockage. Instead, your doctor may need to read your blood pressure at your big toe to get accurate test results if you have either of those conditions.

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