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Brachial Artery Pulsatility Index Change 1 Minute After 5-Minute Forearm Compression

Comparison With Flow-Mediated Dilatation

From Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, São Paulo, Brazil (W.P.M., C.O.N., R.A.F., F.M.F.); and Escola de Ultra-Sonografia e Reciclagem Médica de Ribeirão Preto, São Paulo, Brazil (W.P.M., M.F.).

Address correspondence to Wellington P. Martins, PhD, Departamento de Ginecologia e Obstetrícia, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Avenida dos Bandeirantes 3900, 8° Andar, Ribeirão Preto, 14049-900 São Paulo-SP, Brazil. E-mail: wpmartins{at}gmail.com

Objective. Endothelial impairment evaluation by sonographic measurement of flow-mediated dilatation (FMD) has become broadly used. However, this method has 2 main caveats: the dilatation depends on the baseline arterial diameter, and a high precision level is required. Vasodilatation leads to an amplified fall in impedance. We hypothesized that assessment of the pulsatility index change (PI-C) 1 minute after 5-minute forearm compression might evaluate that fall in impedance. The aim of this study was to compare the PI-C with FMD. Methods. Flow-mediated dilatation and the PI-C were assessed in 51 healthy women aged between 35.1 and 67.1 years. We correlated both FMD and the PI-C with age, body mass index, waist circumference, cholesterol level, high-density lipoprotein level, glucose level, systolic and diastolic blood pressure, pulse pressure, brachial artery diameter, simplified Framingham score, intima-media thickness, and carotid stiffness index. Intraclass correlation coefficients between 2 FMD and PI-C measurements were also examined. Results. Only FMD correlated with baseline brachial diameter (r = –0.53). The PI-C had a high correlation with age, body mass index, waist circumference, cholesterol level, systolic blood pressure, pulse pressure, simplified Framingham score, and intima-media thickness. The correlation between FMD and the PI-C was high (r = –0.66). The PI-C had a higher intraclass correlation coefficient (0.991) than FMD (0.836) but not brachial artery diameter (0.989). Conclusions. The PI-C had a large correlation with various markers of cardiovascular risk. Additionally, PI-C measurement does not require offline analysis, extra software, or electrocardiography. We think that the PI-C could be considered a marker of endothelial function. However, more studies are required before further conclusions.

Key Words: Doppler sonography • endothelium • sonography • vasodilatation

Abbreviations: β, stiffness index • BD, brachial artery basal diameter • BMI, body mass index • CDD, carotid diastolic diameter • CI, confidence interval • CSD, carotid systolic diameter • DBP, diastolic blood pressure • EDV, end-diastolic flow velocity • FMD, flow-mediated dilatation • HDL, high-density lipoprotein • ICC, intraclass correlation coefficient • IMT, intima-media thickness • PI, pulsatility index • PI-C, pulsatility index change • PP, pulse pressure • PSV, peak systolic flow velocity • SBP, systolic blood pressure • TAV, time-averaged flow velocity