Arterial Ultrasound

What is an Arterial Doppler Ultrasound?

An arterial Doppler ultrasound follows blood on its way out from the heart. Arteries are the vessels that carry oxygen-rich blood to the limbs and organs. When plaque narrows one of them, the tissue downstream receives less than it needs. This painless test finds the narrow spot and shows how tight it is. A small handheld device called a transducer is pressed against the skin over the artery. It sends sound waves into the body and listens for the echoes that bounce back. A computer builds two things from those echoes. One is a picture of the vessel. The other is a graph of how fast blood is moving. Color Doppler adds color for the direction of flow, which makes a blocked segment easy to spot. Most requests involve the legs, since that is where poor flow causes symptoms you can feel. The test uses no radiation, no needles, and usually no dye.

The study is done in the office by a trained sonographer. It takes roughly 30 to 60 minutes, depending on how much of the body is examined, and needs no recovery time. Arterial studies are one branch of the wider vascular ultrasound family. The neck arteries have a study of their own, the carotid ultrasound and Doppler. The veins are checked with a venous ultrasound, which hunts for different problems entirely.

Why Dr. Nanavati may recommend this

Arterial Doppler ultrasound answers two practical questions. Is blood flow to a limb or organ reduced? If so, exactly where is the problem?

Dr. Nanavati may recommend it if you have:

• Leg cramping or aching that begins with walking and stops with rest, the classic symptom of peripheral artery disease. The American Heart Association explains peripheral artery disease and why it matters.
• An abnormal or borderline ankle-brachial index that needs to be mapped in more detail.
• A foot or leg wound that will not heal, or foot pain at rest.
• Coldness, numbness, weakness, or color change in an arm or leg.
• A pulsating mass in the abdomen, or screening for an aortic aneurysm, which is a bulge in a weakened artery wall.
• Suspected narrowing of a kidney artery in someone with hard to control blood pressure.
• Follow-up of a previous bypass graft, stent, or dialysis access to make sure it is still open.

The National Heart, Lung, and Blood Institute reviews how reduced circulation is diagnosed and treated.

How to prepare

Preparation depends on which arteries are being studied, so follow the instructions the office gives you.

• For arm and leg studies, no fasting is needed. Eat, drink, and take your medications as usual.
• For studies of the abdominal aorta or the kidney arteries, expect to skip food for about 8 hours beforehand. Gas and food in the bowel obscure the picture. Sips of water with pills are generally fine.
• Do not smoke or use nicotine for at least two hours before the test. Nicotine narrows blood vessels and can distort the measurements.
• Wear loose, two piece clothing that is easy to remove. You may be given a gown.
• Leave necklaces and other jewelry at home when the neck or chest is being scanned.
• Keep taking blood thinners and blood pressure medications unless specifically instructed otherwise.
• Allow about an hour for the appointment.

What happens during the procedure

Where the probe travels depends on which artery is in question. The study is shaped around your symptoms.

For a leg study you lie on your back. The leg is straightened and rolled slightly outward. The sonographer starts high, at the groin, and works downward. The femoral artery in the thigh comes first. Next is the popliteal artery behind the knee, which usually means bending or turning the leg. After that come the vessels running down the calf toward the ankle. Each segment is sampled in turn. A leg study is a series of short stops rather than one long sweep.

Both legs are usually examined. Comparing the two sides is how mild narrowing on one side becomes obvious.

Gel is spread on the skin ahead of the probe. It feels cool, and it clears away the thin layer of air that sound waves cannot cross.

Listen to the speakers. A healthy leg artery makes a sharp, snapping sound with each heartbeat. Past a tight segment that sound flattens into a softer hum. The tracing on the screen changes shape along with it. Your sonographer is listening for exactly that change.

Arm studies follow the same idea, working down from the shoulder. Abdominal studies are different. There the probe presses in more firmly to push bowel gas out of the way. You may be asked to take a breath and hold it while an image is captured. That pressure can feel uncomfortable, but it should not be painful. Say something if it is.

This scan often runs alongside an ankle-brachial index, which compares the blood pressure at your ankle with the pressure at your arm. The two tests answer different halves of one question. The index says how much flow is reduced overall. The ultrasound says where the blockage sits.

Recovery and results

You are free to go as soon as you are dressed. Normal activity resumes at once, with no limits on driving, work, or exercise. If you fasted for an abdominal study, bring a snack for afterward.

A physician reviews and interprets the images. Dr. Nanavati typically has the written report in hand a few days later. In some situations the sonographer can flag an urgent finding right away. Dr. Nanavati then explains the results at a follow-up appointment or by phone.

A normal study means the arteries are open and blood is moving at expected speeds. An abnormal study describes where the narrowing sits and how severe it is. Severity is graded by how much the flow speeds up as it squeezes through the tight segment.

Mild to moderate disease is usually treated without a procedure. A supervised walking program is the cornerstone. Stopping smoking, controlling cholesterol, and controlling blood pressure come next, and medication is sometimes added. Advanced lipid testing can help when your risk is unclear.

Severe disease is handled differently. So is a wound that will not heal, or pain in the foot at rest. Those situations may lead to further imaging and to a catheter-based procedure such as angioplasty.

Risks and safety

Nothing about this study is invasive. No needle goes in, nothing is swallowed, and no dye is given. There is no radiation, so there is no dose to add up across repeat scans.

Comfort depends mostly on where the probe has to go. A leg study is easy for the large majority of people. Tenderness shows up over a bruise, an inflamed vein, or a healing surgical site, and the sonographer can lighten the pressure or work around the spot. Abdominal scanning needs a firmer push and is the part people tend to mention afterward. A full map of both legs can also run close to an hour. That is a long time to lie flat with a sore back or hip, and a pillow under the knees usually solves it.

The limits are worth understanding, because they turn up in exactly the patients who need this test. Long standing diabetes and kidney disease can leave artery walls heavily calcified. Calcium reflects sound, so those segments are hard to grade. Open wounds, dressings, and casts sit between the probe and the artery, and the scan cannot see through them. Bowel gas does the same to the abdominal vessels, which is why fasting is asked for.

When part of the picture is missing, CT or MR angiography usually fills it in. Remember too that this is a snapshot of one moment at rest. Symptoms that come and go may still need further evaluation.

Related services and conditions

• Ankle-brachial index (ABI), the usual first screening test.
• Carotid ultrasound and Doppler for the neck arteries.
• Venous ultrasound for clots and leaking valves in the veins.
• Vascular ultrasound, the overview of all of these scans.
• Aortic aneurysm, often followed with serial ultrasound.
• Coronary artery disease, which frequently coexists.
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