The carotid arteries are a pair of blood vessels located on either side of the neck, delivering oxygen-rich blood directly from the heart up to the brain. These vessels are fundamental to brain function, ensuring a continuous supply of necessary oxygen and nutrients. A carotid bruit (pronounced “broo-ee”) is a finding noted during a physical examination when a doctor listens to the neck with a stethoscope. This abnormal vascular sound is a whooshing or turbulent noise indicating that blood flow in the artery may not be entirely smooth.
Understanding the Sound
The flow of blood through a healthy artery is typically silent because the movement is organized and streamlined, a pattern known as laminar flow. When the interior of the artery becomes irregular or narrowed, this smooth movement is disrupted. The fluid dynamics change, causing the blood to swirl and become disorganized, which is termed turbulent flow. This turbulence creates vibrations against the artery walls that are audible as a bruit when a stethoscope is placed over the carotid artery in the neck.
The intensity and timing of the sound can sometimes provide initial clues about the degree of disruption. For instance, a bruit heard throughout the entire heart cycle may suggest a more advanced condition than one heard only during the heart’s contraction phase. Not every bruit signals a serious problem, as some can be a benign “flow murmur” caused by a high output state, such as in younger individuals or those with anemia. Regardless of the sound’s characteristics, its presence warrants further investigation to determine the exact cause.
Underlying Causes and Associated Risks
The most frequent and concerning cause behind a carotid bruit is carotid artery stenosis, which is the narrowing of the artery. This narrowing is commonly the result of atherosclerosis, a process where fatty deposits, cholesterol, and cellular waste accumulate to form plaque on the artery walls. As this plaque builds up, it constricts the artery’s inner diameter, forcing blood to rush through a smaller opening and generating the characteristic turbulent sound.
The significance of carotid stenosis lies in its potential to increase the risk of an ischemic stroke or a transient ischemic attack (TIA). Plaque deposits can become unstable and rupture, releasing fragments that travel to the smaller vessels in the brain and block blood flow, causing an ischemic stroke. Furthermore, the narrowed area itself can be a site for blood clots to form, which may also travel to the brain. While a bruit in an otherwise healthy, asymptomatic person may prove to be harmless, a bruit caused by significant atherosclerosis represents a heightened long-term risk to brain health.
Evaluation and Treatment Options
Upon hearing a carotid bruit, the next step in evaluation is to determine the severity and exact cause of the turbulent flow. The standard non-invasive test used for this purpose is the carotid duplex ultrasound, also known as a Doppler study. This procedure uses sound waves to create images of the carotid arteries and measures the speed of blood flow through the vessels. The velocity of the blood flow allows medical professionals to accurately calculate the degree of narrowing, or stenosis, present in the artery.
Treatment is then tailored based on the confirmed severity of the stenosis and whether the patient has experienced any related symptoms, such as a TIA. For mild to moderate narrowing, management typically focuses on intensive medical therapy and lifestyle adjustments to slow the progression of atherosclerosis. This approach includes medication to control blood pressure and cholesterol levels, as well as antiplatelet agents like aspirin to reduce the risk of clot formation.
When the artery narrowing is severe (generally defined as 70% or more), or if the patient has experienced a recent TIA or stroke, a surgical procedure may be recommended. Two common procedures are carotid endarterectomy, which involves surgically opening the artery to remove the plaque buildup, and carotid angioplasty and stenting. Stenting is a less invasive option where a small mesh tube is inserted to push the plaque aside and keep the artery open, restoring proper blood flow to the brain.