A carotid bruit is an abnormal sound heard over the carotid artery in the neck. It is detected by a healthcare professional using a stethoscope during a physical examination. The presence of a carotid bruit indicates a disturbance in the normal, smooth flow of blood within these arteries, which supply blood to the brain.
The Distinctive Sound of a Carotid Bruit
A carotid bruit is described as a whooshing, swishing, or blowing sound. It is a vascular sound resulting from turbulent blood flow, similar to water rushing through a constricted pipe. This sound is not usually audible to the patient.
The characteristics of a carotid bruit vary in pitch and intensity. It is often continuous, though it may be predominantly heard during systole, the phase when the heart contracts and pumps blood. As the narrowing in the artery increases, the bruit can become louder and higher-pitched. However, in cases of very severe narrowing or complete blockage, the bruit might diminish or disappear due to insufficient blood flow to create turbulence.
Understanding the Origins of the Sound
The reason for a carotid bruit is turbulent blood flow. Normally, blood flows smoothly through arteries. When there is a narrowing or irregularity in the carotid artery, this smooth flow is disrupted, leading to chaotic blood movement that produces vibrations heard as a bruit.
The most common cause of this narrowing is atherosclerosis, a condition where fatty substances, cholesterol, and other materials build up on the artery walls, forming plaque. This plaque buildup reduces the artery’s internal diameter, restricting blood flow and causing turbulence. Less common causes include anatomical variations like kinking or twisting of the artery, or conditions that increase blood flow, such as anemia or an overactive thyroid.
Clinical Detection and Significance
A carotid bruit is primarily detected through auscultation. The presence of a bruit suggests turbulent blood flow, but it does not definitively diagnose severe carotid artery disease. It can indicate generalized atherosclerosis and may signal an increased risk for stroke.
A bruit alone does not indicate the degree of arterial narrowing, and some bruits can be benign, particularly in younger individuals or those with high-flow states. If a carotid bruit is detected, further diagnostic tests are necessary to assess the extent of underlying narrowing and determine the risk. A carotid duplex ultrasound is commonly the first-line test, providing detailed images and blood flow measurements to identify stenosis or plaque buildup.