Augmented Velocity Index: A New Doppler Index Associated with Arterial Stiffness

Abstract

Augmented Velocity Index (Avi) is a new Doppler index developed to quantify velocity changes at the late systolic peak. We examined its reliability, association with arterial stiffness and cardiovascular risk factors. The Avi is calculated as (late systolic peak velocity − early systolic peak velocity)/(highest peak systolic velocity − end-diastolic velocity). Fifty volunteers (mean age ± standard deviation: 43.5 ± 14.2 y, men: 52%) without known medical illnesses or drug use were recruited. Carotid Doppler waveforms with measurements of Avi were recorded. Carotid pressure waveforms were obtained by applanation tonometry for measurement of the Augmentation Index (AI). Clinical measurements including body mass index (BMI) and blood pressure (BP) were assessed, and fasting blood was taken for measurement of glycemia and lipid profile. Another 15 volunteers (age range: 22–60 y, men: 33.3%) were recruited to study the reliability of Avi measurement. The results revealed that carotid Avi closely correlated with the index of arterial stiffness, AI (r = 0.76, p < 0.001) on Pearson correlation. On multiple linear regression analysis, Avi remained a significant independent determinant of AI after adjustments for clinical variables. The Avi had significant associations with cardiovascular risk factors (age, BMI, total cholesterol, low-density lipoprotein cholesterol, systolic and diastolic BP). The intra-class correlation coefficients for inter-observer and intra-observer reliability of Avi measurements were 0.93 (95% confidence interval [CI]: 0.8–0.98) and 0.97 (95% CI: 0.92–0.99) respectively. In conclusion, the Avi is a reproducible new Doppler index, independently associated with arterial stiffness in terms of the AI, which initially correlated with cardiovascular risk factors.