Nonstenotic Internal Carotid Arteries: Effects of Age and Blood Pressure at the Time of Scanning on Doppler US Velocity Measurements

PURPOSE: To assess the effects of age and blood pressure at the time of scanning on internal carotid artery velocities and cross-sectional diameter at Doppler ultrasonography (US). MATERIALS AND METHODS: During 12 months, 1,020 consecutive patients underwent internal carotid artery Doppler US. No or minimal arterial disease was found in 142 patients (67 women, 75 men). Blood pressure was recorded prior to examination. The angle-corrected internal carotid artery peak systolic and end-diastolic velocities were obtained. The effects of systolic blood pressure, diastolic blood pressure, pulse pressure, age, chronic hypertension, and medications for hypertension on velocities were evaluated by using linear regression analysis. RESULTS: Peak systolic velocity was influenced by age (P =.008), systolic blood pressure (P =.009), diastolic blood pressure (P =.003), and pulse pressure (P =.017) but not history of hypertension (P =.53) or antihypertensive medication use (P =.77). Increasing age decreased peak systolic velocity by 0.34 cm/sec/y. End-diastolic velocity was influenced by age (P <.001) but not by systolic, diastolic, or pulse pressure (all P values were >.13). CONCLUSION: Internal carotid artery peak systolic velocities decrease with advancing age and increase with increasing pulse pressure. The effects of blood pressure at the time of scanning are small, but isolated systolic hypertension could cause increases in spurious velocity.