An overview of Ankle Brachial Index
An ankle-brachial index test is a simple medical test used to check for peripheral artery disease (PAD), a condition characterized by narrowed or blocked arteries that reduce blood flow to the arms and legs. The test compares the blood pressure measured at the ankle with the blood pressure measured at the arm. A low ankle-brachial index number may indicate narrowing or blockage of the arteries in the legs. The test can be performed before and after walking on a treadmill, called an exercise ankle-brachial index test, to assess the impact of exercise on blood flow.
What is Ankle Brachial Index used for?
An ankle-brachial index test is used to check for peripheral artery disease (PAD). PAD occurs when arteries in the legs become narrowed or blocked, reducing blood flow and causing leg pain, particularly during walking. The ankle-brachial index test compares blood pressure measured at the ankle with the blood pressure measured at the arm. A low ankle-brachial index number can indicate artery narrowing or blockages in the legs. It might be done before and after walking on a treadmill (exercise ankle-brachial index test) to assess the severity of artery narrowing during walking. The test can help identify risk factors for heart attack and stroke and guide appropriate treatment.
How to prepare for Ankle Brachial Index?
No special preparations are needed for an ankle-brachial index test. The test is painless and similar to having blood pressure taken in a routine medical visit. Wear loose, comfortable clothing to allow the provider to easily place a blood pressure cuff on an ankle and upper arm.
How is Ankle Brachial Index conducted?
An ankle-brachial index test is conducted by measuring blood pressure at the ankle and arm using an inflatable cuff and a hand-held ultrasound device. The provider will likely ask you to rest for a short period before the test and then measure blood pressure in both arms and both ankles. The test is painless and similar to having blood pressure taken during a routine medical visit. No special preparations are needed, and you can expect to wear loose, comfortable clothing for the test.
How are Ankle Brachial Index results reported?
The ankle-brachial index results are reported based on the calculated ratio of blood pressure measurements from the arms and ankles. The results are categorized into three ranges:
- No blockage (1.0 to 1.4)
- Borderline blockage (0.90 to 0.99)
- PAD (less than 0.90)
A range of 1.0 to 1.4 indicates no blockage, suggesting that the person probably does not have PAD. A range of 0.90 to 0.99 indicates borderline PAD, and a result below 0.90 indicates a diagnosis of PAD. In some cases, further testing, such as ultrasound or angiography, may be necessary to view the arteries in the legs.
Understanding the report
An ankle-brachial index between 1.0 to 1.4 indicates no blockage, suggesting that there is no PAD (Peripheral Artery Disease). However, if you have symptoms of PAD, an exercise ankle-brachial index test might be performed. An ankle-brachial index between 0.90 to 0.99 indicates borderline PAD. You might have an exercise ankle-brachial index test. An ankle-brachial index less than 0.90 indicates PAD. Further testing, such as ultrasound or angiography, might be required to view the arteries in your legs. It's important to note that these interpretations are based on the information provided and may vary depending on individual circumstances. Consult with a healthcare provider for personalized advice and interpretation.
Limitations and Considerations
The ankle-brachial index test is a useful tool for detecting peripheral artery disease (PAD), but it does have some limitations. One limitation is that it may not always accurately diagnose PAD, particularly in people with diabetes or those who have had previous heart or blood vessel surgery. Additionally, the test may not be appropriate for individuals with certain conditions, such as deep vein thrombosis or severe leg swelling. In cases where the test results are inconclusive or there are concerns about the accuracy of the test, further diagnostic tests, such as an ultrasound or angiography, may be required.