What Is An Ankle Brachial Index (ABI)?
The Ankle Brachial Index or ABI refers to the ratio of the blood pressure in the upper half of the body (the arms) in relation to the lower half (the legs). The ABI is figured by dividing the top blood pressure number in the ankle by the top blood pressure number in the arm. These numbers are gathered through use of a Doppler Wand or Doppler Probe and cuff.
When Might I Need To Know My Ankle Brachial Index?
Your doctor may calculate your ABI to check for:
- Peripheral Arterial Disease
- Ulcers
- Atherosclerosis
- Vessel Hardening
- Blood Flow Restrictions
The ABI of a healthy subject should reveal a slightly higher systolic pressure at the ankle than at the arm. If the ABI reads high or low, it can be an indicator of the issues listed above.
An Ankle Brachial Index can also be used to evaluate the body’s response to a specific treatment, surgery, exercise program, etc.
What Should I Expect?
In order to calculate your ABI, your doctor will place a blood pressure cuff on your arm. The cuff will be inflated and the Doppler Wand will be used to measure when the artery stops pulsing. Once pulsing ceases, the cuff begins to deflate. As the cuff deflates, the pulse of the artery should be detected and the number on the Doppler Wand at the first detection is the systolic pressure (top blood pressure number). The first reading is done while you are at rest. A second reading will most likely be done after a slight increase in heart rate (i.e. a brief stint on a treadmill).
This process is then repeated on your ankle in order to get the systolic pressure of that specific artery.
How Should I Prepare For An ABI?
You will not need to do anything to prepare for an ABI, other than remove clothing from the arm and ankle during the procedure.
If you have questions about the Ankle Brachial Index, please be sure to ask during your next visit.