Noninvasive Measurement of Transient Change in Viscoelasticity Due to Flow-Mediated Dilation Using Automated Detection of Arterial Wall Boundaries

2011 ◽  
Vol 50 (7S) ◽  
pp. 07HF08 ◽  
Author(s):  
Kazuki Ikeshita ◽  
Hideyuki Hasegawa ◽  
Hiroshi Kanai
Keyword(s):  
Arterial Wall ◽  
Automated Detection ◽  
Noninvasive Measurement ◽  
Flow Mediated Dilation ◽  
Transient Change

In Vivo Measurements of Change in Viscoelasticity of Arterial Wall During the Flow-Mediated Dilation

2009 ◽  
Author(s):  
Hiroshi Kanai ◽  
Hideyuki Hasegawa ◽  
Kazuki Ikeshita
Keyword(s):  
Elastic Modulus ◽  
Endothelial Function ◽  
Hysteresis Loop ◽  
Arterial Wall ◽  
Radial Strain ◽  
Least Square ◽  
Flow Mediated Dilation ◽  
Transient Change ◽  
In Vivo Measurements

The present paper introduces in vivo measurements of viscoelasticity of arterial wall developed in our laboratory. The endothelial dysfunction is considered to be an earliest stage of atherosclerosis. Moreover, it was reported that the smooth muscle, which constructs the media of the artery, changes its characteristics due to atherosclerosis. Therefore, it is essential to develop an in vivo measurement method to assess the regional endothelial function and mechanical property (viscoelasticity) of the arterial wall. To evaluate the endothelial function, there is a conventional technique for measuring the transient change in the diameter of the brachial artery caused by flow mediated dilation (FMD) after the release of avascularization. However, this method does not directly evaluate the viscoelasticity of the intima-media region of the arterial wall. In the present paper, therefore, we proposed a method for simultaneous measurement of waveforms of the radial strain and blood pressure at the radial artery, and we developed its measurement system. From in vivo experiments, the viscoelasticity parameters of the arterial wall were estimated from the measured stress-strain relationship (hysteresis loop) using the least-square method and their transient changes after the release of avascularization were revealed. For healthy young persons, the slope of the hysteresis loop decreased due to the FMD, which corresponds to decrease in the elastic modulus. At the same time, the area of the loop increased after recirculation, which corresponds to the increase of the ratio of the loss modulus (viscosity) to the elastic modulus when the Voigt model is assumed. These results show a potential of the proposed method for thorough analysis of the transient change in viscoelasticity due to FMD.

scholarly journals Brachial artery vasodilatory response and wall shear rate determined by multigate Doppler in a healthy young cohort

2018 ◽  
Vol 124 (1) ◽  
pp. 150-159 ◽  
Author(s):  
Kunihiko Aizawa ◽  
Sara Sbragi ◽  
Alessandro Ramalli ◽  
Piero Tortoli ◽  
Francesco Casanova ◽  
...  
Keyword(s):  
Shear Rate ◽  
Brachial Artery ◽  
Arterial Wall ◽  
Reactive Hyperemia ◽  
Wall Shear Rate ◽  
Young Cohort ◽  
Flow Mediated Dilation ◽  
Detailed Measurement ◽  
Vascular Physiology ◽  
Wall Shear

Wall shear rate (WSR) is an important stimulus for the brachial artery flow-mediated dilation (FMD) response. However, WSR estimation near the arterial wall by conventional Doppler is inherently difficult. To overcome this limitation, we utilized multigate Doppler to accurately determine the WSR stimulus near the vessel wall simultaneously with the FMD response using an integrated FMD system [Ultrasound Advanced Open Platform (ULA-OP)]. Using the system, we aimed to perform a detailed analysis of WSR-FMD response and establish novel WSR parameters in a healthy young population. Data from 33 young healthy individuals (27.5 ± 4.9 yr, 19 females) were analyzed. FMD was assessed with reactive hyperemia using ULA-OP. All acquired raw data were postprocessed using custom-designed software to obtain WSR and diameter parameters. The acquired velocity data revealed that nonparabolic flow profiles within the cardiac cycle and under different flow states, with heterogeneity between participants. We also identified seven WSR magnitude and four WSR time-course parameters. Among them, WSR area under the curve until its return to baseline was the strongest predictor of the absolute ( R2 = 0.25) and percent ( R2 = 0.31) diameter changes in response to reactive hyperemia. For the first time, we identified mono- and biphasic WSR stimulus patterns within our cohort that produced different magnitudes of FMD response [absolute diameter change: 0.24 ± 0.10 mm (monophasic) vs. 0.17 ± 0.09 mm (biphasic), P < 0.05]. We concluded that accurate and detailed measurement of the WSR stimulus is important to comprehensively understand the FMD response and that this advance in current FMD technology could be important to better understand vascular physiology and pathology. NEW & NOTEWORTHY An estimation of wall shear rate (WSR) near the arterial wall by conventional Doppler ultrasound is inherently difficult. Using a recently developed integrated flow-mediated dilation ultrasound system, we were able to accurately estimate WSR near the wall and identified a number of novel WSR variables that may prove to be useful in the measurement of endothelial function, an important biomarker of vascular physiology and disease.

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