ANKLE-BRACHIAL INDEX (ABI)
Diagnostic Testing & Imaging
What is the ankle-brachial index?
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The ankle-brachial index (ABI) is a noninvasive measurement that is used to assess how well blood is flowing in your legs. The ankle-brachial index is determined by measuring the blood pressure in the ankle and dividing it by the blood pressure in the upper arm. The test takes around 10 to 15 minutes and is typically performed in a clinical setting by a vascular technician.
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How is the ankle-brachial index measured?
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During the ankle-brachial index test, the patient is typically instructed to lie on their back while blood pressure cuffs are placed on the ankles and the upper arms. An ultrasound device is pressed against the skin nearby to determine blood pressure in the ankles and upper arms.
Ankle-Brachial Index (ABI)
What is the ankle-brachial index used for?
The ankle-brachial index (ABI) is used to help diagnose peripheral artery disease (PAD) in the legs. A lower ankle-brachial index score (less than 1.0) may indicate that your legs are affected by narrowed or blocked arteries. ABI scores are interpreted as follows:
ABI 1.0 to 1.3 - Healthy blood flow
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Indicates that the arteries in your legs are probably healthy
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ABI 0.9 to 0.99 - Some narrowing or blockage possible
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Indicates that the arteries in your legs may be affected by some degree of peripheral artery disease
ABI less than 0.9 - Peripheral artery disease (PAD)
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Indicates that the arteries in your legs are probably affected by significant peripheral artery disease
The ankle-brachial index is a useful test to determine if peripheral artery disease is affecting your legs, but it does not provide any information on which of your arteries are affected. If your ABI score is severe, your cardiologist may suggest an ultrasound or angiographic imaging study to identify treatment opportunities.
References
[1] Aboyans, V., Criqui, M. H., Abraham, P., Allison, M. A., Creager, M. A., Diehm, C., … Treat-Jacobson, D. (2012). Measurement and interpretation of the Ankle-Brachial Index: A scientific statement from the American Heart Association. Circulation, 126(24), 2890–2909.
