TY - JOUR
T1 - Mechanism underlying the heart rate dependency of wave reflection in the aorta
T2 - a numerical simulation
AU - Xiao, Hanguang
AU - Tan, Isabella
AU - Butlin, Mark
AU - Li, Decai
AU - Avolio, Alberto P.
PY - 2018/3/1
Y1 - 2018/3/1
N2 - Arterial wave reflection has been shown to have a significant dependence on heart rate (HR). However, the underlying mechanisms inherent in the HR dependency of wave reflection have not been well established. This study aimed to investigate the potential mechanisms and role of arterial viscoelasticity using a 55-segment transmission line model of the human arterial tree combined with a fractional viscoelastic model. At varying degrees of viscoelasticity modeled as fractional order parameter α, reflection magnitude (RM), reflection index (RI), augmentation index (AIx), and a proposed novel normalized reflection coefficient (Γnorm) were estimated at different HRs from 60 to 100 beats/min with a constant mean flow of 70 ml/s. RM, RI, AIx, and Γnorm at the ascending aorta decreased linearly with increasing HR at all degrees of viscoelasticity. The means ± SD of the HR dependencies of RM, RI, AIx, and Γnorm were -0.042 ± 0.004, -0.018 ± 0.001, -1.93 ± 0.55%, and -0.037 ± 0.002 per 10 beats/ min, respectively. There was a significant and nonlinear reduction in RM, RI, and Γnorm with increasing α at all HRs. In addition, HR and α have a more pronounced effect on wave reflection at the aorta than at peripheral arteries. The potential mechanism of the HR dependency of wave reflection was explained by the inverse dependency of the reflection coefficient on frequency, with the harmonics of the pulse waveform moving toward higher frequencies with increasing HR. This HR dependency can be modulated by arterial viscoelasticity. NEW & NOTEWORTHY This in silico study addressed the underlying mechanisms of how heart rate influences arterial wave reflection based on a transmission line model and elucidated the role of arterial viscoelasticity in the dependency of arterial wave reflection on heart rate. This study provides insights into wave reflection as a frequencydependent phenomenon and demonstrates the validity of using reflection magnitude and reflection index as wave reflection indexes.
AB - Arterial wave reflection has been shown to have a significant dependence on heart rate (HR). However, the underlying mechanisms inherent in the HR dependency of wave reflection have not been well established. This study aimed to investigate the potential mechanisms and role of arterial viscoelasticity using a 55-segment transmission line model of the human arterial tree combined with a fractional viscoelastic model. At varying degrees of viscoelasticity modeled as fractional order parameter α, reflection magnitude (RM), reflection index (RI), augmentation index (AIx), and a proposed novel normalized reflection coefficient (Γnorm) were estimated at different HRs from 60 to 100 beats/min with a constant mean flow of 70 ml/s. RM, RI, AIx, and Γnorm at the ascending aorta decreased linearly with increasing HR at all degrees of viscoelasticity. The means ± SD of the HR dependencies of RM, RI, AIx, and Γnorm were -0.042 ± 0.004, -0.018 ± 0.001, -1.93 ± 0.55%, and -0.037 ± 0.002 per 10 beats/ min, respectively. There was a significant and nonlinear reduction in RM, RI, and Γnorm with increasing α at all HRs. In addition, HR and α have a more pronounced effect on wave reflection at the aorta than at peripheral arteries. The potential mechanism of the HR dependency of wave reflection was explained by the inverse dependency of the reflection coefficient on frequency, with the harmonics of the pulse waveform moving toward higher frequencies with increasing HR. This HR dependency can be modulated by arterial viscoelasticity. NEW & NOTEWORTHY This in silico study addressed the underlying mechanisms of how heart rate influences arterial wave reflection based on a transmission line model and elucidated the role of arterial viscoelasticity in the dependency of arterial wave reflection on heart rate. This study provides insights into wave reflection as a frequencydependent phenomenon and demonstrates the validity of using reflection magnitude and reflection index as wave reflection indexes.
KW - heart rate
KW - reflection coefficient
KW - transmission line model
KW - viscoelasticity
KW - wave reflection
UR - http://www.scopus.com/inward/record.url?scp=85043757058&partnerID=8YFLogxK
U2 - 10.1152/ajpheart.00559.2017
DO - 10.1152/ajpheart.00559.2017
M3 - Article
C2 - 29101182
AN - SCOPUS:85043757058
SN - 0363-6135
VL - 314
SP - H443-H451
JO - American Journal of Physiology - Heart and Circulatory Physiology
JF - American Journal of Physiology - Heart and Circulatory Physiology
IS - 3
ER -