Names & Terms You Will Hear
Plain-language meanings for the terms your care team may use.
| Term | Meaning |
|---|---|
| Ankle-brachial index (ABI) | The ankle blood pressure divided by the arm blood pressure. Around 1.00 is normal; below 0.90 suggests narrowed leg arteries. |
| Ankle-brachial pressure index (ABPI) | The same test under a slightly different name. ABI and ABPI mean the same thing. |
| Resting ABI | The number measured while you lie still. This is the standard ABI. |
| Exercise (treadmill) ABI | The ABI measured again right after walking on a treadmill. It can reveal mild disease the resting test misses. |
| Doppler ultrasound | A small handheld probe that listens to blood flow. It marks the moment the artery reopens as the cuff deflates. |
| Brachial pressure | The blood pressure in the arm artery (the brachial artery). It is the bottom number of the ABI ratio. |
| Peripheral artery disease (PAD) | Narrowed leg arteries from plaque buildup. A low ABI is the main way it is found. |
| Non-compressible vessels | Stiff, hardened ankle arteries that the cuff cannot squeeze. They give a falsely high ABI (above 1.40). |
| Toe-brachial index (TBI) | Toe pressure divided by arm pressure. Used instead of the ABI when ankle vessels are too stiff to compress. |
| Borderline ABI | A result between 0.90 and 1.00. Often followed by an exercise ABI to settle the question. |
What Is the Ankle-Brachial Index?
- The ankle-brachial index (ABI) is a quick, painless test that compares the blood pressure at your ankle to the blood pressure in your arm.
- Your care team divides the ankle pressure by the arm pressure. In a healthy person the two pressures are about equal, so the number lands around 1.00.
- If the leg arteries are narrowed by plaque, less pressure reaches the ankle. The ankle number drops, so the ABI falls below the arm value.
- An ABI below 0.90 suggests peripheral artery disease (PAD) — narrowed leg arteries. The lower the number, the more severe the narrowing.
- The test uses blood pressure cuffs and a small handheld ultrasound probe (a Doppler). There are no needles, no dye, and no radiation.
- It usually takes about 15 minutes. You lie still while the cuffs inflate at the arm and the ankle, one limb at a time.
- Sometimes the test is repeated right after you walk on a treadmill. Exercise can bring out mild narrowing that a resting test misses.
- A result above 1.40 is too high to be normal. It usually means the ankle arteries are stiff and cannot be squeezed by the cuff — a different test is needed.
The Treadmill (Exercise) ABI — Unmasking Borderline Disease
A resting ABI can look normal even when the leg arteries are mildly narrowed. Walking demands more blood flow, so a narrowing that is hidden at rest shows up under load.
For an exercise ABI, your resting number is measured first. Then you walk on a treadmill until your legs ache or for a set time. The ABI is measured again right away.
A clear drop after exercise (a fall of more than 20 percent from your resting value) points to PAD, even if the resting number was normal. It also shows your team how far you can walk before flow falls off.
A resting ABI can look normal even when the leg arteries are mildly narrowed. Walking demands more blood flow, so a narrowing that is hidden at rest shows up under load.
For an exercise ABI, your resting number is measured first. Then you walk on a treadmill until your legs ache or for a set time. The ABI is measured again right away.
A clear drop after exercise (a fall of more than 20 percent from your resting value) points to PAD, even if the resting number was normal. It also shows your team how far you can walk before flow falls off.
Why It Matters
- A low ABI is the simplest way to catch peripheral artery disease early — often before it causes leg pain.
- Narrowed leg arteries can cause cramping in the calf, thigh, or buttock when you walk that eases with rest. This is called claudication. (See our claudication guide.)
- Just as important: a low ABI is a whole-body warning. The same plaque that narrows leg arteries narrows heart and brain arteries too.
- People with a low ABI have a higher risk of heart attack and stroke — even if their legs feel fine. So a leg test is also a heart-risk test.
- Catching a low ABI early lets your team start treatments that protect both the legs and the heart at the same time.
- A stiff-vessel result (above 1.40) is its own flag. It is common in diabetes and kidney disease and means the arteries are hardened — worth a closer look with a toe test.
- The test is cheap, fast, and safe, so it is easy to repeat over time to see whether things are stable, improving, or getting worse.
ABI Range, What It Means, and What Usually Happens Next
| ABI Range | What It Means | What Usually Happens Next |
|---|---|---|
| Above 1.40 | Stiff, non-compressible vessels. The number is not reliable. Common in diabetes and kidney disease. | A toe-brachial index (TBI) is ordered to get a true reading. |
| 1.00 to 1.40 | Normal. The ankle and arm pressures are about equal. | No PAD found. Keep arteries healthy; recheck if leg symptoms appear. |
| 0.90 to 1.00 | Borderline. Mildly low — may be early PAD. | Often repeated after treadmill walking (exercise ABI) to settle it. |
| 0.40 to 0.90 | Mild to moderate PAD. The range where leg cramping with walking is common. | Risk-factor control, a walking program, statin, and antiplatelet. |
| Below 0.40 | Severe PAD. Blood flow is very low; rest pain or non-healing wounds can occur. | Prompt vascular specialist referral; imaging and possible procedure. |
What Your ABI Number Means
- Around 1.00 (the normal band is about 1.00 to 1.40): the ankle and arm pressures are about equal, which is what a healthy leg looks like.
- 0.90 to 1.00 (borderline): mildly low. Your team may repeat the test after treadmill walking to decide whether mild PAD is present.
- 0.40 to 0.90 (mild to moderate PAD): narrowing is present. This is the range where many people get cramping with walking (claudication).
- Below 0.40 (severe PAD): blood flow is very low. The foot may hurt at rest or develop wounds. This needs prompt specialist care.
- Remember the direction: the lower the number, the more narrowed the artery. Higher is healthier — up to the normal ceiling of about 1.40.
When the Number Is Falsely High (Stiff Vessels)
- A result above 1.40 is too high to be a normal, healthy reading. It almost always means the ankle arteries are stiff and hardened.
- Stiff arteries resist the cuff, so the cuff has to push to a very high pressure before the artery closes. That inflates the number and can hide real disease.
- This is common in diabetes and chronic kidney disease, where artery walls build up calcium over time.
- The fix is a toe-brachial index (TBI): a tiny cuff on the big toe, where the small vessels are far less likely to be stiff. A TBI below 0.70 suggests PAD.
- So a high ABI is not reassuring on its own. If you were told yours was above 1.40, ask whether a toe test is the right next step.
Why a Leg Test Reflects Whole-Body Risk
- Atherosclerosis (plaque buildup) is rarely limited to one spot. The same process that narrows leg arteries narrows the heart and brain arteries too.
- Because the legs are easy to measure, a low ABI acts as a window onto the rest of the arteries — a low leg number predicts higher heart-attack and stroke risk.
- This holds even when the legs feel fine. People can have a low ABI and no symptoms, yet still carry the higher whole-body risk.
- That is why a low ABI changes more than leg care: it usually means starting a statin and an antiplatelet to protect the heart and brain.
- It also ties the legs to the rest of the picture — see our guides on the coronary calcium score, carotid artery disease, and diabetes and the heart.
Risk Factors
Knowing your personal risks helps your care team take extra precautions.
| Risk Factor | Why It Increases Risk |
|---|---|
| Leg cramping with walking (claudication) | Cramping in the calf, thigh, or buttock that comes on with walking and eases with rest is the classic reason to check an ABI. |
| Age 65 or older | PAD becomes much more common with age. Many people have it without knowing, so an ABI is a reasonable check. |
| Age 50 or older with diabetes or a smoking history | These two raise PAD risk enough that screening starts earlier — at 50 instead of 65. |
| Diabetes | High blood sugar damages artery walls and the leg nerves. Nerve damage can hide leg pain, so PAD is easy to miss without a test. |
| Smoking (current or past) | Tobacco is the strongest single driver of leg artery disease. A smoker's ABI is worth checking even without symptoms. |
| A wound on the foot or toe that will not heal | Poor blood flow slows healing. A non-healing foot wound is a reason to measure the ABI promptly. |
| Known heart disease, stroke, or carotid disease | Plaque in one artery bed means plaque is likely elsewhere. An ABI checks the legs as part of the bigger picture. |
Treatment Options
Shown in English for your safety — this section is not automatically translated. Confirm with your doctor or call the office.
- The ABI itself is a test, not a treatment. What follows depends on the number and on how your legs feel.
- If the ABI is normal (about 1.00 to 1.40): no PAD is found. Your team focuses on keeping your arteries healthy and may recheck later if symptoms appear.
- If the ABI is borderline (0.90 to 1.00): the test may be repeated after treadmill walking (an exercise ABI) to settle whether mild PAD is present.
- If the ABI is low (below 0.90): PAD is confirmed. The first steps are risk-factor control — stop smoking, treat blood pressure, lower cholesterol with a statin, and manage diabetes.
- A structured walking program is the best first treatment for leg cramping. Walking to mild discomfort, resting, then walking again trains the muscles and builds new small vessels.
- Medicines such as a statin and an antiplatelet (aspirin or clopidogrel) lower the risk of heart attack and stroke for almost everyone with a low ABI.
- Imaging (ultrasound, CT, or MRI of the leg arteries) is added only when symptoms are severe or a procedure is being considered — not for every abnormal ABI.
- If the ABI is above 1.40 (stiff vessels): the number is unreliable. Your team orders a toe-brachial index (TBI), which uses a tiny cuff on the toe, where vessels are less likely to be stiff.
Comfort Measures at Home (No Medication Needed)
These simple steps support healing and ease symptoms. Use them alongside any medication your doctor prescribes.
- There is nothing painful about the test. You may feel the cuffs squeeze briefly, the same as a routine blood pressure check.
- Wear loose clothing so the cuffs reach the upper arms and the ankles easily.
- Plan to rest quietly for 5 to 10 minutes before the resting test. Rushing in from the parking lot can change the numbers.
- Avoid caffeine and tobacco for an hour or two beforehand if you can — both can briefly change blood flow.
- If a treadmill (exercise) ABI is planned, wear comfortable shoes and tell the staff how far you can usually walk before your legs hurt.
- Ask for your number and what range it falls in before you leave. Knowing whether you are normal, borderline, low, or stiff-vessel helps you follow the plan.
Risks, Benefits, and Alternatives
Shown in English for your safety — this section is not automatically translated. Confirm with your doctor or call the office.
Every choice has trade-offs. Use this table to start the shared decision conversation with your care team.
| Option | Risks | Benefits | Alternatives |
|---|---|---|---|
| Resting ABI | Can read normal in mild disease. Falsely high if ankle vessels are stiff. | Fast, painless, no needles or radiation. Confirms or rules out PAD in most people. Also flags heart risk. | Exercise ABI; toe-brachial index; artery ultrasound. |
| Exercise (treadmill) ABI | Requires walking; not for those who cannot exercise safely. Takes longer. | Reveals mild PAD a resting test misses. Shows how far you can walk before flow drops. | Resting ABI alone; pharmacologic or imaging tests if you cannot walk. |
| Toe-brachial index (TBI) | Needs a small toe cuff and a steady toe signal. Slightly more involved. | Works when ankle vessels are too stiff to measure (above 1.40). Common in diabetes and kidney disease. | Artery ultrasound; CT or MRI of the leg arteries. |
| Artery ultrasound / CT / MRI | More time and cost. CT and some MRI use contrast dye that can stress the kidneys. | Shows exactly where and how long a blockage is. Used to plan a procedure. | ABI or TBI first; reserve imaging for severe symptoms or pre-procedure planning. |
Common Misconceptions
| Myth | Reality |
|---|---|
| MYTH: The ABI is a heart test, so it has nothing to do with my legs. | FACT: The ABI is a leg test — it measures blood flow to the ankles. But because the same plaque affects the whole body, a low leg number also flags higher heart-attack and stroke risk. |
| MYTH: A normal ABI means my leg arteries are completely fine. | FACT: A resting ABI can read normal in mild PAD. If you get leg cramps when walking but your resting number is normal, ask about an exercise (treadmill) ABI, which can unmask it. |
| MYTH: A high ABI is even better than a normal one. | FACT: A value above 1.40 is too high to be normal. It usually means the ankle arteries are stiff and the cuff cannot squeeze them, hiding real disease. A toe test gives the true picture. |
| MYTH: The test will hurt or involves needles. | FACT: The ABI uses blood pressure cuffs and a small ultrasound probe. There are no needles, no dye, and no radiation. You only feel the cuffs squeeze briefly. |
| MYTH: If my legs do not hurt, an abnormal ABI does not matter. | FACT: Many people with a low ABI have no leg pain, especially with diabetes, where nerve damage hides it. The number still signals real disease and higher heart risk worth treating. |
| MYTH: One abnormal ABI means I need a procedure right away. | FACT: Most abnormal ABIs are managed first with risk-factor control, a walking program, and medicines. Imaging and procedures are reserved for severe symptoms or limb-threatening disease. |
Possible Complications
Knowing what can go wrong helps you spot problems early. Most complications are uncommon, especially with treatment.
| Where / What | What Can Happen |
|---|---|
| The test itself | The ABI is very safe. There are no needles, dye, or radiation. The treadmill version carries the usual small risks of any exercise test and is supervised. |
| Leg — claudication | A low ABI often goes with cramping when walking that eases with rest. Untreated, the walking distance can shrink over time. |
| Leg — critical limb-threatening ischemia | A very low ABI (below 0.40) signals blood flow so poor that the foot can hurt at rest or develop wounds. This needs prompt specialist care. |
| Heart and brain — atherosclerosis elsewhere | A low ABI is a marker that plaque is active body-wide, raising the risk of heart attack and stroke even when the legs feel fine. |
| Falsely normal or high reading | Stiff (non-compressible) ankle vessels can hide real disease behind a normal-looking or high ABI. A toe-brachial index avoids this trap. |
| Missed disease without exercise testing | A resting ABI can read normal in mild PAD. If symptoms suggest PAD but the resting number is fine, an exercise ABI is the next step. |
A Low ABI Is a Heart-and-Brain Warning, Not Just a Leg Result
The same plaque that narrows leg arteries narrows the arteries to the heart and brain. So a low ABI raises the risk of heart attack and stroke — even if your legs feel fine.
That is why an abnormal ABI usually leads to whole-body steps:
• A statin to lower cholesterol and steady the plaque.
• An antiplatelet (aspirin or clopidogrel) in most people.
• Blood pressure and blood sugar control.
• Stopping smoking — the single most powerful step.
Treating a low ABI protects far more than your legs.
The same plaque that narrows leg arteries narrows the arteries to the heart and brain. So a low ABI raises the risk of heart attack and stroke — even if your legs feel fine.
That is why an abnormal ABI usually leads to whole-body steps:
• A statin to lower cholesterol and steady the plaque.
• An antiplatelet (aspirin or clopidogrel) in most people.
• Blood pressure and blood sugar control.
• Stopping smoking — the single most powerful step.
Treating a low ABI protects far more than your legs.
Points to Know
Shown in English for your safety — this section is not automatically translated. Confirm with your doctor or call the office.
If you remember nothing else, remember these key points.
- The ABI divides ankle pressure by arm pressure. Around 1.00 is normal; below 0.90 suggests narrowed leg arteries (PAD).
- The lower the number, the more severe the narrowing. Below 0.40 is severe and needs prompt specialist care.
- A value above 1.40 is not better than normal — it means stiff vessels. Your team will order a toe-brachial index instead.
- The test is fast, painless, and safe: blood pressure cuffs and a small ultrasound probe, no needles or radiation, about 15 minutes.
- If your legs hurt with walking but the resting number is normal, ask about an exercise (treadmill) ABI to bring out mild disease.
- A low ABI is a whole-body heart-risk flag. The same plaque narrows heart and brain arteries, so treatment protects more than your legs.
- Most abnormal results are managed first with stopping smoking, a statin, blood pressure and diabetes control, and a walking program.
When to Call Us — and When to Call 911
Shown in English for your safety — this section is not automatically translated. Confirm with your doctor or call the office.
If you are not sure, call. We would rather hear from you twice than miss a real problem.
- Call 911 immediately: sudden, severe leg pain with a cold, pale, or blue foot and no pulse. This can be a sudden artery blockage and needs emergency care within hours.
- Call your doctor the same day: a new wound, sore, or blister on the foot or toe that is not healing — especially if you have diabetes.
- Call your doctor within the week: foot or leg pain at rest, often worse at night, that eases when you dangle the foot off the side of the bed.
- Schedule a visit: cramping, aching, or tiredness in the calf, thigh, or buttock that comes on with walking and goes away within about 10 minutes of rest.
- Schedule a visit: one foot that is cooler, paler, or more numb than the other.
- Schedule a visit: you are 65 or older (or 50 or older with diabetes or a smoking history) and have never had an ABI.
- Ask about a toe test: you were told your ABI was above 1.40 or could not be measured because the ankle vessels were too stiff.
Office: (727) 943-5200
Trusted Resources
Independent, evidence-based pages we recommend for deeper reading.
- Cleveland Clinic — Ankle-Brachial Index (ABI) Test — Plain-language explanation of the test, the numbers, and what they mean
- AHA — Diagnosing Peripheral Artery Disease — American Heart Association overview of the ABI as the first-line PAD test
- Mayo Clinic — Peripheral Artery Disease (diagnosis) — Patient-facing description of the ABI procedure and the treadmill version
- NIH MedlinePlus — Ankle-Brachial Index — NIH/NLM page on how the test is done and what the values mean
- Our Peripheral Artery Disease guide — What a low ABI means for your legs — causes, stages, and treatment
Sources Used to Build This Guide
- Cleveland Clinic — Ankle-Brachial Index (ABI) Test [patient_education] — Plain-language overview of comparing ankle and arm blood pressures to screen for peripheral artery disease and interpret the ratio.
- American Heart Association — Peripheral Artery Disease and the ABI [patient_education] — Positions the ABI as the first-line, noninvasive test for PAD and what an abnormal result means.
- MedlinePlus — Ankle-Brachial Index [patient_education] — NIH/NLM description of how the test is performed and the meaning of normal, borderline, and low ABI values.
- 2016 AHA/ACC Guideline on the Management of Patients With Lower Extremity Peripheral Artery Disease [guideline] — Authoritative basis for ABI thresholds (0.90 cutoff), the 1.00 to 1.40 normal band, exercise/post-exercise ABI (greater than 20 percent drop is abnormal), and the noncompressible above 1.40 finding requiring a toe-brachial index.
- Mayo Clinic — Ankle-Brachial Index Test [patient_education] — Patient-facing description of the cuff-and-Doppler procedure, the roughly 15-minute timing, and the optional treadmill (exercise) version.
- AHA Scientific Statement — Measurement and Interpretation of the Ankle-Brachial Index (Circulation 2012) [guideline] — Standardized methodology for measuring the ABI and the source of the borderline 0.91 to 0.99 category and the noncompressible above 1.40 definition.
- U.S. Preventive Services Task Force — Screening for PAD and CVD Risk With the ABI [guideline] — USPSTF position on ABI screening in asymptomatic adults, including the severity bands used to describe mild, moderate, and severe disease.
- Sensitivity and Specificity of the ABI to Predict Future Cardiovascular Outcomes (ATVB 2005) [research] — Supports the test-accuracy framing: an ABI of 0.90 or lower has high specificity (about 95 percent) for significant leg-artery narrowing and predicts cardiovascular risk.
- Post-Exercise ABI Decline and Risk of All-Cause Mortality: A Meta-Analysis (Eur J Prev Cardiol 2020) [research] — Evidence that a treadmill-induced ABI drop unmasks borderline disease and carries prognostic weight, supporting the exercise-ABI section.
- Cleveland Clinic — Peripheral Artery Disease (PAD) [patient_education] — Companion condition page explaining what a low ABI implies for the legs and whole-body atherosclerosis, used for the why-it-matters framing.
