Hemodynamic studies of the audiofrequency analysis of carotid bruits

The contribution of carotid audiofrequency analysis to the noninvasive diagnosis of carotid arterial lesions requires clarification. Carotid arterial stenoses were simulated in the dog and the following measurements were made: proximal and distal arterial pressure, blood flow, percent area reduction, and carotid audiofrequency analysis. A 40% area reduction produced a systolic bruit but no interference with flow or pressure. A 60% area reduction produced a pansystolic bruit and a reduction in peak systolic flow (precritical stenosis). A 70% area reduction produced a systolic bruit that extended into diastole, a reduction in mean blood flow, and an increased pressure gradient (critical stenosis). At total occlusion, there was no recordable heart sound or bruit. Carotid audiofrequency analysis can establish the hemodynamic importance of a carotid artery lesion and it is an essential component of any noninvasive examination.