Carotid bruit Carotid bruit A carotid bruit is a vascular murmur sound (bruit) heard over the carotid artery area on auscultation during systole. It may occur as the result of carotid artery stenosis (though some disagree); however, most carotid bruits, particularly those found in younger or asymptomatic patients, are not related to any disease and are termed "innocent carotid bruits". A carotid bruit is unlikely to be heard if the stenosis occludes less than 40% of the diameter of the artery. Likewise, a stenosis of greater than 90% may not be heard, as the flow may be too low. Many carotid bruits
Carotid body acid-base transporters (e.g. Na-H) which raise intracellular pH, and activates transporters (e.g. Cl-HCO) which decrease it. Changes in proton concentration caused by acidosis (or the opposite from alkalosis) inside the cell stimulates the same pathways involved in P sensing. Another mechanism is through oxygen sensitive potassium channels. A drop in dissolved oxygen lead to closing of these channels which results in depolarization. This leads to release of the neurotransmitter dopamine in the glossopharyngeal and vagus afferente to the vasomotor area. The type I (glomus) cells in the carotid (and aortic bodies) are derived from neuroectoderm and are thus electrically excitable.