17840 Ankle Brachial Index Abi

Overview

The ankle brachial index (ABI) is a quick, painless test that compares the blood pressure in your ankle with the blood pressure in your arm. The result shows how well blood is flowing down to your legs and feet. It is the main test used to look for peripheral arterial disease (PAD) — a condition where arteries in the legs become narrowed or blocked, so the muscles and skin get less blood and oxygen than they need. The word 'brachial' simply refers to the artery in your arm, and 'ankle' to the artery at your ankle.

The ABI test is very common — it is used all over the world in GP surgeries, vascular (blood vessel) clinics and hospitals. The condition it looks for, peripheral arterial disease, is also common: it becomes more likely with age and is thought to affect roughly 1 in 5 people over the age of 60. Many people with narrowed leg arteries have no symptoms at all, which is one reason this simple test is so useful.

The ABI test can be done at any age, but it is most often used for adults over 50, and especially people over 60. It is also used for younger adults who have risk factors such as diabetes, smoking, high blood pressure, high cholesterol, kidney problems, or a strong family history of heart or circulation disease. It is only rarely used in children, and then only in specialist care.

Symptoms

Common symptoms

• Cramping or aching in the calf, thigh or buttock that comes on when walking and eases with a few minutes' rest — this is called intermittent claudication
• Legs that feel heavy, tired or weak with exercise
• Cold feet or lower legs, even in warm weather
• Hair loss on the legs or feet, or shiny, tight-looking skin on the lower legs
• Slow-growing or brittle toenails
• Sores or ulcers on the feet or lower legs that are slow to heal
• Erectile difficulties in men, which can be an early sign of narrowed arteries
• No symptoms at all — many people with narrowed leg arteries feel completely well

Symptoms in children

• The ABI test is not routinely used in children
• It is occasionally done in specialist paediatric care for children with particular heart or blood vessel conditions
• Children's blood pressure and circulation are usually assessed in other ways first

Symptoms in older adults

• Symptoms may be put down to 'just getting older', so leg cramps or slow walking are worth mentioning to your doctor
• Narrowed leg arteries are more common with age, especially after 60
• Older adults are more likely to have stiff arteries, which can make the ABI reading higher than expected — your clinician will know how to interpret this
• The test is safe and well tolerated, including for people with limited mobility

Causes

Main causes

• The ABI test itself does not have causes — but an abnormal result is usually caused by peripheral arterial disease, where fatty deposits (called plaque) build up inside the leg arteries and narrow them
• This build-up is the same process that causes heart attacks and strokes, just in a different part of the body
• Less often, an abnormal result can come from stiff, hardened arteries, which happen with age, diabetes or kidney disease
• Rarely, other blood vessel conditions or injury to an artery can affect the reading

Risk factors

• Smoking or having smoked in the past — this is the biggest single risk factor
• Diabetes (type 1 or type 2)
• High blood pressure
• High cholesterol
• Chronic kidney disease
• Being over 60, or over 50 with other risk factors
• A family history of heart disease, stroke or circulation problems
• Being physically inactive
• Being overweight
• An unhealthy diet high in saturated fat and salt

When to see a doctor

See a doctor urgently if:

• You have a foot wound or ulcer that is not healing
• You have new pain in your foot or leg while resting
• Your leg or foot has changed colour, or feels much colder than usual
• You have diabetes and notice any new problem with your feet

Book a routine appointment if:

• You get cramping leg pain when you walk that eases with rest
• Your legs feel heavy or tired easily during exercise
• You have cold feet, slow-healing cuts, or hair loss on your lower legs
• You have risk factors for circulation problems and have never had your circulation checked
• You have already had an ABI test and want to understand your result

Diagnosis

The ABI is measured with a blood pressure cuff and a small handheld device called a Doppler probe, which uses sound waves to hear the pulse in your arteries. You will usually lie flat on a couch. The cuff is placed on your upper arm and inflated to measure your arm blood pressure, then placed just above your ankle and inflated again while your clinician listens to the pulse with the probe. The test is repeated on both sides, and sometimes on the toes as well. It is painless apart from the tight feeling of the cuff.

Tests that may be done

• Ankle brachial index (ABI) — the main test
• Toe brachial index (TBI) — sometimes used if your leg arteries are too stiff for a reliable ABI
• A pulse check and listen to the arteries in your groin, knee and foot
• Duplex ultrasound — a painless scan that shows blood flow and any narrowing in the arteries
• Blood tests for cholesterol, blood sugar and kidney function
• Blood pressure and heart checks, to assess your overall heart and stroke risk
• Sometimes a CT or MRI angiogram (a detailed scan of the blood vessels), usually only if a procedure is being considered

What to expect at your appointment

The test is quick and you can go home straight afterwards. Wear loose trousers or shorts so your legs can be reached easily, and avoid smoking for at least two hours beforehand, as smoking can temporarily affect blood flow. You may be asked to rest for a few minutes before the reading. Your clinician may explain the result on the day, or you may be given a follow-up appointment to discuss it along with any other tests. Ask for the number and what it means in your case — it is fine to ask questions.

Treatment

The ABI test is a check, not a treatment. What happens next depends on your result. If it is normal, no treatment is usually needed, though your clinician may suggest a repeat test later if your risk factors change. If it shows narrowed leg arteries, the focus is on protecting your heart and circulation, easing symptoms, and keeping your feet healthy. Treatment usually means a combination of lifestyle changes, foot care and medicines, with procedures considered only if symptoms are severe or your feet are at risk.

Self-care at home

• If you smoke, stopping is the single most effective thing you can do — ask your GP or pharmacist about local stop-smoking support
• Stay active: a daily walk, building up gradually, helps your muscles use oxygen more efficiently
• Check your feet every day, including between the toes, and look for cuts, blisters, redness or nail problems
• Wash and dry your feet carefully, and use moisturiser on dry skin but not between the toes
• Wear well-fitting shoes and socks, and never walk barefoot if your circulation is poor or you have diabetes
• Keep your feet warm, but avoid direct heat such as hot water bottles or radiators on your feet
• Cut toenails straight across, and see a foot specialist (podiatrist) if this is difficult or you have diabetes
• Attend your routine check-ups for blood pressure, cholesterol and blood sugar

Medical treatments

Your doctor may suggest medicines to lower cholesterol, bring blood pressure into a healthy range, or reduce the risk of blood clots — these protect your heart and brain as well as your legs. If you have diabetes, good blood sugar control matters a great deal. A supervised exercise programme is often recommended for leg pain when walking; it involves walking regularly to the point of mild discomfort, then resting, and repeating. Your doctor or nurse will explain which options suit you, and you should never start, stop or change any medicine without speaking to them first. A podiatrist can help with foot care, and a vascular specialist will advise if a procedure is needed.

When is surgery considered?

Most people do not need surgery or a procedure. If leg pain is severe, is limiting your daily life, or if your foot is at risk, a vascular specialist may discuss options such as angioplasty (widening the artery with a small balloon, sometimes with a tiny mesh tube called a stent) or bypass surgery (using a vein or a man-made tube to route blood around a blocked section). These are usually only considered after lifestyle changes and medicines have been tried, and your specialist will explain the benefits and risks in your own situation.

Living with this condition

Many people with narrowed leg arteries live full and active lives. The key is to build gentle, regular movement into your day, look after your feet, and keep up with your check-ups. Plan walks with places to rest, and tell people around you if you need to slow down. If you notice any new sore on your foot, get it looked at quickly rather than waiting.

Lifestyle tips

• Stop smoking — support is available and it really does make a difference
• Be active most days, even if it is short walks to begin with
• Eat a heart-healthy diet with plenty of vegetables, fruit, whole grains, beans, nuts and oily fish
• Cut down on salt and saturated fat
• Keep to a healthy weight, or aim for gradual, steady weight loss if you need to
• Limit alcohol to within recommended levels
• Take your medicines as prescribed and keep repeat prescriptions up to date
• Look at your feet daily — a mirror or a family member can help if bending is hard

Diet and exercise

A Mediterranean-style way of eating — vegetables, fruit, whole grains, pulses, nuts, olive oil and fish, with less red meat and processed food — is often recommended for heart and circulation health. For exercise, walking is one of the best options. Try walking until you feel mild discomfort, then rest until it settles, and repeat for 30 to 45 minutes on most days. Over weeks, you may find you can go further before the pain starts. Check with your doctor before starting a new exercise plan if you have other health conditions, and ask about a supervised exercise programme if walking is difficult.

Mental health and emotional wellbeing

It is very common to feel worried or frustrated when you are told you have a circulation problem, or when leg pain changes what you can do. Some people feel anxious about their heart or about the future. These feelings are understandable and worth talking about. Tell your GP or practice nurse how you are feeling — support such as counselling, a supervised exercise group or a local support group can help a lot. If you ever feel you cannot cope, please contact your local crisis support service or your local emergency number straight away.

Prevention

You cannot change your age or your family history, but you can lower your risk of narrowed leg arteries a great deal. The biggest steps are not smoking, staying active, eating well, keeping blood pressure and cholesterol in a healthy range, and managing diabetes carefully if you have it. These steps protect your heart and brain too, not just your legs.

Vaccines

People with circulation problems and diabetes are sometimes advised to have routine vaccinations, such as the yearly flu vaccine. Ask your GP, practice nurse or pharmacist which vaccinations are recommended for you.

Screening programmes

The ABI is not currently offered as a routine screening test for everyone. It is usually done when you have symptoms, when your doctor notices something on examination, or when you have risk factors such as diabetes, smoking or a strong family history. If you think you may be at risk, it is reasonable to ask your GP whether a circulation check is appropriate for you.

Complications

If left untreated

• Leg pain that limits how far you can walk
• Skin breakdown and leg or foot ulcers that are slow to heal
• Infection in the foot, which can be serious, especially with diabetes
• In severe cases, gangrene (tissue dying from lack of blood), which may lead to amputation
• A higher risk of heart attack and stroke, because the same disease process affects the whole body

Long-term outlook

The outlook is often good, especially when narrowed arteries are found early. Many people's symptoms stay stable or improve with lifestyle changes and medicines, and most people never need surgery. Finding out that you have a circulation problem gives you a real opportunity to protect your heart and legs — small, steady changes really do add up. Your healthcare team is there to help you at each step.

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