A carotid bruit is a whooshing or swishing sound a doctor hears through a stethoscope placed on your neck, over one of the carotid arteries that supply blood to your brain. It’s caused by turbulent blood flow, usually where the artery has narrowed. A bruit itself isn’t a disease. It’s a physical finding that signals something is restricting normal blood flow, most often a buildup of fatty plaque inside the artery wall.
How the Sound Is Produced
Blood normally flows through arteries in smooth, parallel layers. When part of the artery narrows, blood has to squeeze through a tighter space. That forces it to speed up, and the orderly flow breaks apart into chaotic swirls. Those turbulent swirls vibrate the artery wall, and the vibrations travel outward to the skin surface, where a stethoscope can pick them up.
The character of the sound changes as narrowing worsens. When the artery’s inner diameter is about 50% blocked, a soft, brief sound appears during the heartbeat’s pumping phase. At around 60% narrowing, the sound becomes higher-pitched and louder. Between 70% and 80%, it can extend beyond the pumping phase into the resting phase of the heartbeat. Paradoxically, once the blockage becomes very severe, so little blood gets through that there isn’t enough turbulence to make a sound. The bruit can disappear entirely, even though the situation has become more dangerous.
What Causes the Narrowing
The most common cause is atherosclerosis, the gradual buildup of cholesterol-rich plaque inside artery walls. The same process that clogs coronary arteries in heart disease affects the carotid arteries, especially at the point where each one splits into internal and external branches. Risk factors are the familiar ones: high blood pressure, high cholesterol, smoking, diabetes, and aging.
Less commonly, a bruit can result from conditions unrelated to plaque. These include carotid artery dissection (a tear in the artery wall), fibromuscular dysplasia (abnormal growth of cells in the artery wall that creates a beaded narrowing pattern), moyamoya disease (progressive narrowing of arteries at the base of the brain), and large vessel vasculitis (inflammation of the artery). A bruit can also appear in younger, healthy people during high-output states like pregnancy, severe anemia, or an overactive thyroid, when the heart pumps blood so forcefully that turbulence occurs even in normal arteries.
How It’s Found
Most carotid bruits are discovered incidentally during a routine physical exam. Your doctor places the bell of a stethoscope on the side of your neck, roughly at the angle of the jaw where the carotid artery branches. You may be asked to hold your breath briefly so breathing sounds don’t interfere.
One challenge is telling a true carotid bruit apart from a heart murmur that simply radiates up into the neck. Heart murmurs tend to be loudest over the chest and fade as the stethoscope moves toward the head. A bruit originating in the carotid artery is loudest right over the branching point in the neck and isn’t detectable over the chest wall. Still, this distinction can be tricky by ear alone, which is one reason further testing is usually the next step.
What Happens After a Bruit Is Detected
Hearing a bruit doesn’t tell a doctor exactly how severe the narrowing is. The standard follow-up is a carotid duplex ultrasound, a painless, noninvasive scan that combines a regular ultrasound image of the artery with measurements of blood flow speed. The faster the blood moves through a segment, the tighter the narrowing at that point. A peak flow speed above roughly 250 cm/s at the narrowest spot indicates severe stenosis, meaning the artery has lost more than 70% of its opening. Moderate stenosis shows lower speeds with visible plaque. In near-complete blockages, flow speeds actually drop very low because almost nothing is getting through, but fresh clot or extensive plaque is visible on the image.
The ultrasound results determine what comes next. If narrowing is mild, the focus shifts to medical management and monitoring. If it’s severe, more detailed imaging or a surgical consultation may follow.
Stroke Risk With an Asymptomatic Bruit
Finding a bruit when you’ve had no symptoms (no episodes of sudden vision loss, weakness, numbness, or speech trouble) places you in a category called asymptomatic carotid stenosis. The natural question is: how worried should you be?
Long-term data show the annual stroke risk from asymptomatic narrowing of 50% or more is less than 1% per year. For narrowing under 50%, it’s about 1% per year. These are relatively low numbers, and they’ve gotten even lower in the modern era of cholesterol-lowering medications and blood pressure control. This is why the U.S. Preventive Services Task Force recommends against screening the general population for carotid stenosis. They concluded with moderate certainty that routine screening, including listening for bruits, has no net benefit and may lead to unnecessary procedures that carry their own risks.
That said, a bruit discovered during an exam isn’t ignored. It’s treated as a marker of cardiovascular disease throughout the body. People with carotid bruits face higher overall rates of heart attack and vascular events, not just stroke.
Medical Management
For most people with a carotid bruit and mild to moderate stenosis, treatment focuses on slowing plaque progression and reducing cardiovascular risk broadly. The core elements include cholesterol-lowering medication (typically a statin), low-dose aspirin, blood pressure control targeting below 120/80, blood sugar management if diabetes is present, and lifestyle changes like quitting smoking, regular exercise, and maintaining a healthy weight. The American Heart Association recommends keeping total cholesterol below 200, fasting blood sugar below 100, and BMI below 25 as targets to delay atherosclerotic disease.
These measures work. Modern medical therapy has reduced the stroke risk from asymptomatic stenosis substantially compared to decades ago, which is part of why the threshold for recommending surgery has shifted.
When Surgery Is Considered
Two procedures can physically open a narrowed carotid artery. Carotid endarterectomy involves a surgeon making an incision in the neck, opening the artery, and removing the plaque. Carotid artery stenting uses a catheter threaded through a blood vessel to place a small mesh tube that props the artery open. The indications for both are similar.
For people who have already had symptoms (a recent stroke, transient ischemic attack, or repeated episodes of temporary vision loss in one eye), surgery is typically recommended when narrowing exceeds 50%. Current European guidelines set a formal threshold at 70% for symptomatic patients, with discussion starting at 50%. For asymptomatic patients, the conversation about surgery begins at 60% or greater narrowing, but only when imaging and other factors suggest a high long-term stroke risk. Because the annual stroke risk with medical therapy alone is already low for asymptomatic patients, the potential benefit of surgery has to clearly outweigh the procedural risks.
If you’re told you have a carotid bruit, the most likely path forward is an ultrasound, a conversation about your overall cardiovascular risk, and a plan built around medication and lifestyle changes. Surgery enters the picture only when the numbers and circumstances clearly justify it.