What Is an Ankle Brachial Index Test?

When you first hear “ankle brachial index test,” you might think it’s for checking for an injury or strain in your ankle. However, the simple, non-invasive test is performed to check for a potentially dangerous artery condition. 

Let’s break down exactly why and how the test is performed.

Why Is Ankle Brachial Index Important?

So exactly what is an ankle brachial index, and why is it important? The ankle-brachial index test is a quick way to check for peripheral artery disease (PAD). 

PAD is a disease where plaque builds up in the arteries of the arms or, more typically, the legs. The narrowed arteries restrict the blood flow to the extremities, which can cause pain and numbness when walking. Other symptoms of PAD can include:

• Muscle pain in the arms or legs that begins with exercise and ends with rest 
• Painful cramping in the legs after climbing stairs
• Coldness in the lower foot or leg
• Shiny skin on the legs
• Slow-growing toenails
• Sores on the feet or legs that won’t heal

If you are experiencing any of these symptoms, your doctor may wish to perform an ankle brachial index (ABI) test, which compares the blood pressure in the upper and lower limbs to see if PAD could be present.

How Is the Test Performed?

The ABI test is very straightforward and simple. You lie down on your back, and the medical professional takes your blood pressure in each of your arms, and then measures your blood pressure in each of your ankles. They do this by using blood pressure cuffs and a hand-held ultrasound device that's pressed on the skin. 

The technician then uses these numbers to compute your ABI. 

How Is the Test Performed?

The technician will do some quick math by dividing the blood pressure of the ankle by the blood pressure of the arm. Your index number will put you in one of three groups:

• 1.4 to 1.0: You likely don’t have PAD.*
• .99 to .90: You might have borderline PAD, meaning your peripheral arteries may be starting to narrow, but blood flow through them isn't blocked.
• Less than .90: You likely have PAD. 

If you’re experiencing symptoms of PAD but have a high ABI, you may be asked to undergo an exercise ankle brachial index test. This is a very similar test, but it’s completed before and after you walk on a treadmill, so the medical professional can see how much the arteries are restricted while walking.

Who Should Take an ABI Test?

If you have any symptoms of PAD, your doctor will likely recommend you undergo the easy ankle brachial index test. Additionally, if you have any of the risk factors for PAD, you may also be a good candidate for the test. Factors that can increase your risk of PAD include:

• Having diabetes
• Smoking
• Being older than 70
• Having plaque formation in other arteries, like in your heart
• Abnormal pulses in your lower legs
• High levels of lipids in your blood
• Being younger than 50, with diabetes and one additional risk factor

What to Do Following a PAD Diagnosis

While an ABI test won’t show exactly which blood vessels are narrowed, it’s an important test for a doctor to know if further treatment is required. 

If you learn you have peripheral artery disease or borderline PAD, speak to your doctor about treatment options. Oftentimes, these include lifestyle changes, like a healthier diet or more exercise. Certain at-home devices, like an SCD machine, can also be helpful in stimulating blood movement. 

To speak with our experienced team about our deep inventory of compression equipment to treat PAD and similar diseases, contact the medcom group today.