What is the ankle brachial index?

The ankle-brachial index test is a procedure for checking a person's risk of peripheral artery disease, says Mayo Clinic. The test compares a person's blood pressure taken at the ankle with that measured at the arm.

If the ankle-brachial index number is low, it may mean the patient has narrowing or blockage of the arteries in the leg, which can lead to circulatory problems, heart disease or stroke, explains Mayo Clinic. The index is calculated by dividing the higher of the two blood pressure measurements taken from the arteries near the left ankle with the higher of the two measurements taken from each arm.