What is involved in an Ankle-Brachial Index Test?
The ankle-brachial index (ABI) is an uncomplicated test that contrasts the blood pressure in the superior and lower extremities. Healthcare providers calculate the ABI (ankle-brachial index) by dividing the blood pressure in an artery in your ankle by the blood pressure in an artery in your arm.
The result is the ankle-brachial index (ABI). If the ratio is less than 0.9, it may mean that an individual has peripheral artery disease (PAD) in the blood vessels of the legs.
In peripheral artery disease, plaque builds up in the arteries. It frequently affects the vessels that carry blood to the legs. Reduced blood flow may provoke pain and numbness. In addition, a low ankle-brachial index may mean that your legs and feet are not getting as much blood as they need.
However, an ankle-brachial index test will show only some of which blood vessels are the ones narrowed or blocked.
During an ankle-brachial index test, you lie on your back. A technician measures your blood pressure in both arms with an inflatable cuff similar to the one used in a doctor’s office. The specialized technician also measures the blood pressure in your ankles. The physician or healthcare provider uses these values to calculate your ABI.
Some Reasons Why Someone Would Need an Ankle-brachial Index Test
Your physician or healthcare provider might want you to take an ankle-brachial index test if you are at risk for peripheral artery disease (PAD).
Ankle-brachial index testing can help in various ways, for example:
- Diagnosing peripheral artery disease (PAD) and preventing its progression and complications.
- Identifying individuals who are at significant risk for coronary artery disease.
Factors that may increase your risk of peripheral artery disease include the following:
- To be older than seventy years old.
- High blood lipid levels.
- Visible plaque formation in other arteries, such as the heart’s coronary arteries.
- Abnormal pulses in the lower legs.
- To be younger than fifty years old, with diabetes and an extra risk factor, such as high blood pressure or smoking.
Your physician or healthcare provider may also recommend an ankle-brachial index test if you experience symptoms of peripheral artery disease, such as leg discomfort with activity. But not everyone with peripheral artery disease has symptoms. This situation makes testing even more important.
You may also need an ankle-brachial index test to check the severity of your peripheral artery disease. Your physician may order this test yearly to see if your condition worsens.
If you had surgery on the blood vessels in your legs, your physician might want an ankle-brachial index test to see how well blood flows into your leg. In addition, physicians sometimes use ankle-brachial index tests to evaluate your risk of a stroke or heart attack in the future.
Risks of an Ankle-brachial Index Test
Most individuals have no risks associated with an ankle-brachial index test. However, experts do not recommend this test if you suffer from a blood clot in your leg. In addition, you may need a different test if you have severe leg pain.
How Do I Get Ready for an Ankle-brachial Index Test?
Fortunately, you must do very little to get ready for an ankle-brachial index test. You can follow a regular diet on the day of the test. In addition, you should not need to stop taking any medications before the procedure.
You may want to wear loose-fitting, comfortable clothing. Wearing loose clothing will allow the expert technologist to place the blood pressure device on your arm and ankle smoothly. You will need to rest for at least fifteen to thirty minutes before the procedure.
Always ask your physician or healthcare provider for special instructions.
What Goes on During an Ankle-brachial Index Test?
The ankle-brachial index test is very similar to a typical blood pressure test. Ask your physician or healthcare provider what to expect. In general, during your ankle-brachial index test, you can expect the following:
- You will lie flat during the procedure.
- An expert technician will place a blood pressure device above your ankle.
- The expert technologist will put an ultrasound tube over the artery. Then, the technologist will use this ultrasound tube to listen to the blood flow throughout the vessels.
- The expert technician will inflate the blood pressure device. Then, the technician will raise the pressure until the blood stops flowing through the vessel. This process may be a little uncomfortable, but it will not hurt.
- The expert technician will slowly release the pressure in the device. This systolic pressure will be the pressure at which the operator will hear the blood flow again. That is the reading of the blood pressure measurement that the operator needs for the ankle-brachial index.
- The expert technician will repeat this procedure on your other ankle and both arms.
- Next, the technician will calculate the ankle-brachial index (ABI). The numerator (top number) is the highest systolic blood pressure found at the ankles. The denominator (lower number) is the most elevated systolic blood pressure found in the arms.
Sometimes, physicians combine an ankle-brachial index test with a physical activity test. For example, you may have an ABI done before and after exercise to see how physical activity changes this value.
Ankle-brachial Index Interpretation
After the ABI test, see your physician or healthcare provider for the results. The number your physician calculates will tell you more about the condition of your arteries:
- Over 1.4: A result at or above this level means your arteries are too stiff to get a meaningful ABI reading. Your physician will probably use a different test.
- to 1.4: This is a regular ankle-brachial index measurement and suggests no blockage in the arteries.
- .90 to .99: Experts consider acceptable results within this range, but it may mean you are borderline at risk for developing peripheral artery disease.
- Below .90: An ankle-brachial index measurement below .90 indicates significant blockage and moderate or severe peripheral artery disease (PAD).
Based on your measurement, your physician may order additional tests or develop a treatment plan for peripheral artery disease (PAD). Common treatments include lifestyle changes or medications to help control or slow disease progression. Severe PAD (scores below 0.50) may require surgery.
What an Abnormal Reading Would Mean
Your physician may be concerned if your ratio is below .9. This ratio is what various studies call “a powerful independent marker of cardiovascular risk.” It puts you at risk of developing progressively shorter walking distances (lifestyle-limiting claudication).
In advanced stages, peripheral artery disease progresses to chronic limb-threatening ischemia (CLTI). Patients have pain at rest (continuous burning pain) due to lack of blood flow and develop non-healing wounds. Patients suffering from CLTI have a dramatically higher amputation rate than patients with intermittent claudication.
Nevertheless, although peripheral artery disease does not cause heart or neurological disease, patients with PAD typically have atherosclerotic disease in other blood vessels. Therefore, physicians associate having peripheral artery disease with an increased risk of major damaging cardiac events that do not affect the limbs, such as heart attack or stroke.
Your physician will also want to consider any possible signs of peripheral vascular disease you may be experiencing before making a diagnosis.
Before making a diagnosis, your physician will consider your family and smoking history and an examination of your legs for signs such as weakness, numbness, or lack of pulse.
Consult a Cardiologist at Modern Heart and Vascular Institute
After an ankle-brachial index test, you should be able to resume normal activities immediately.
Be sure to follow up with your physician about your results. Sometimes, you may need follow-up tests to get more information about a blocked vessel. This follow-up could include an MRI or arteriogram.
You may need treatment if you have peripheral artery disease (PAD). Possible treatments include:
- Smoking cessation
- Treating high blood pressure, high cholesterol, and diabetes.
- Staying physically active
- Eating a healthy diet
- Intake medication to increase blood flow to the legs or prevent blood clots from forming.
- Having procedures to restore blood flow, such as angioplasty
- Have surgery on your leg if the blockage is severe.
- Talk to your physician about your ABI value.
At Modern Heart and Vascular Institute, you can consult a cardiologist to determine if you need an ankle-brachial index test or another cardiovascular exam. Contact us today to request an appointment.
We are here to answer vital questions about how often you should check your heart or how other conditions could affect your heart. Our team of expert cardiologists is here to help you manage, prevent, and treat all aspects of cardiovascular disease.
If you notice any warning signs of health concern, call 9-1-1; you can help avoid irremediable injury by going to a hospital within one hour of a stroke.
This article does not provide medical advice; its intention is solely for informational purposes. All recommendations are not a substitute for professional medical consultation, treatment, or diagnosis. If you need cardiovascular care, call us now at 832 644 8930.
We are Modern Heart and Vascular Institute, a diagnostic and preventative medicine cardiology practice. For more information, contact us.
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We are Modern Heart and Vascular Institute, a diagnostic and preventative medicine cardiology practice.
Every heart has a story… What’s yours?
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This article does not provide medical advice. It is intended for informational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. If you need cardiovascular care, please call us at 832-644-8930.