Acute Hemodynamic Improvement by Thermal Vasodilation inside the Abdominal and Iliac Arterial Segments of Young Sedentary Individuals

2021 ◽  
pp. 1-15
Author(s):  
Zhongyou Li ◽  
Wentao Jiang ◽  
Stephen Salerno ◽  
Yi Li ◽  
Yu Chen ◽  
...  
Keyword(s):  
Blood Flow ◽  
Arterial Compliance ◽  
Lumped Parameter Model ◽  
Mean Flow ◽  
Doppler Measurement ◽  
Iliac Arteries ◽  
Lumped Parameter ◽  
Relative Residence Time ◽  
Hemodynamic Improvement ◽  
Heating Duration

<b><i>Objective:</i></b> To study the hemodynamic response to lower leg heating intervention (LLHI) inside the abdominal and iliac arterial segments (AIAS) of young sedentary individuals. <b><i>Methods:</i></b> A Doppler measurement of blood flow was conducted for 5 young sedentary adults with LLHI. Heating durations of 0, 20, and 40 min were considered. A lumped parameter model (LPM) was used to ascertain the hemodynamic mechanism. The hemodynamics were determined via numerical approaches. <b><i>Results:</i></b> Ultrasonography revealed that the blood flow waveform shifted upwards under LLHI; in particular, the mean flow increased significantly (<i>p</i> &#x3c; 0.05) with increasing heating duration. The LPM showed that its mechanism depends on the reduction in afterload resistance, not on the inertia of blood flow and arterial compliance. The time-averaged wall shear stress, time-averaged production rate of nitric oxide, and helicity in the external iliac arteries increased more significantly than in other segments as the heating duration increased, while the oscillation shear index (OSI) and relative residence time (RRT) in the AIAS declined with increasing heating duration. There was a more obvious helicity response in the bilateral external iliac arteries than the OSI and RRT responses. <b><i>Conclusion:</i></b> LLHI can effectively induce a positive hemodynamic environment in the AIAS of young sedentary individuals.

scholarly journals A Distributed Lumped Parameter Model of Blood Flow

2020 ◽  
Vol 48 (12) ◽  
pp. 2870-2886
Author(s):  
Mehran Mirramezani ◽  
Shawn C. Shadden
Keyword(s):  
Blood Flow ◽  
Lumped Parameter Model ◽  
Lumped Parameter

Dynamics of cerebral blood flow regulation explained using a lumped parameter model

2002 ◽  
Vol 282 (2) ◽  
pp. R611-R622 ◽  
Author(s):  
Mette S. Olufsen ◽  
Ali Nadim ◽  
Lewis A. Lipsitz
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Cardiovascular Response ◽  
Lumped Parameter Model ◽  
Initial Increase ◽  
Windkessel Model ◽  
Cerebrovascular Resistance ◽  
Posture Change ◽  
Lumped Parameter ◽  
Young Subjects

The dynamic cerebral blood flow response to sudden hypotension during posture change is poorly understood. To better understand the cardiovascular response to hypotension, we used a windkessel model with two resistors and a capacitor to reproduce beat-to-beat changes in middle cerebral artery blood flow velocity (transcranial Doppler measurements) in response to arterial pressure changes measured in the finger (Finapres). The resistors represent lumped systemic and peripheral resistances in the cerebral vasculature, whereas the capacitor represents a lumped systemic compliance. Ten healthy young subjects were studied during posture change from sitting to standing. Dynamic variations of the peripheral and systemic resistances were extracted from the data on a beat-to-beat basis. The model shows an initial increase, followed approximately 10 s later by a decline in cerebrovascular resistance. The model also suggests that the initial increase in cerebrovascular resistance can explain the widening of the cerebral blood flow pulse observed in young subjects. This biphasic change in cerebrovascular resistance is consistent with an initial vasoconstriction, followed by cerebral autoregulatory vasodilation.

Characterization of pulmonary arterial input impedance with lumped parameter models

1987 ◽  
Vol 252 (3) ◽  
pp. H585-H593 ◽  
Author(s):  
B. J. Grant ◽  
L. J. Paradowski
Keyword(s):  
Input Impedance ◽  
Goodness Of Fit ◽  
Arterial Compliance ◽  
Characteristic Impedance ◽  
Lumped Parameter Model ◽  
Pulmonary Vasculature ◽  
Impedance Spectra ◽  
Lumped Parameter ◽  
Lumped Parameter Models ◽  
Pulmonary Arterial

The purpose of this study is to evaluate systematically the ability of lumped parameter models to approximate pulmonary arterial input impedance (Zin) and estimate characteristic impedance (Zc) and pulmonary arterial compliance (Cart). To assess goodness of fit, the parameters of each model were adjusted so that the model's impedance approximates the Zin measured in anesthetized cats. To assess the ability of the model to estimate Zc and Cart, the lumped parameter models were fitted to Zin calculated from a distributed parameter model of the feline pulmonary vasculature. In addition, we assessed the concordance between the lumped parameter model estimates of Zc and Cart. The results indicate that no one model was superior; any of four models would be a reasonable choice. A four-element model was used to compare Zin measured at different phases of the respiratory cycle. Small differences in the impedance spectra were found that have not been previously reported. We conclude that lumped parameter models can be used to provide close approximations to Zin, to estimate Zc and Cart, and to provide a useful approach for statistical comparisons of impedance spectra.

Numerical investigation of multiphase blood flow coupled with lumped parameter model of outflow

2019 ◽  
Vol 30 (1) ◽  
pp. 228-244
Author(s):  
Bartlomiej Melka ◽  
Wojciech P. Adamczyk ◽  
Marek Rojczyk ◽  
Marcin L. Nowak ◽  
Maria Gracka ◽  
...  
Keyword(s):  
Blood Flow ◽  
Lumped Parameter Model ◽  
Coarctation Of Aorta ◽  
Multiphase Model ◽  
Computational Domain ◽  
Windkessel Model ◽  
Content Type ◽  
Model Based ◽  
Lumped Parameter ◽  
Euler Approach

Purpose The purpose of this paper is the application of the computational fluid dynamics model simulating the blood flow within the aorta of an eight-year-old patient with Coarctation of Aorta. Design/methodology/approach The numerical model, based on commercial code ANSYS Fluent, was built using the multifluid Euler–Euler approach with the interaction between the phases described by the kinetic theory of granular flow (KTGF). Findings A model of the blood flow in the arches of the main aorta branches has been presented. The model was built using the multifluid Euler–Euler approach with the interaction between the phases described by the KTGF. The flow and pressure patterns, as well as the volumetric concentration of the blood components, were calculated. The lumped parameter model was implemented to couple the interaction of the computational domain with the remaining portion of the vascular bed. Originality/value The multiphase model based on the Euler–Euler approach describing blood flow in the branched large vessel with a three-element Windkessel model in the coarcted geometry was not previously described in the literature.

A lumped parameter model of cerebral blood flow control combining cerebral autoregulation and neurovascular coupling

2012 ◽  
Vol 303 (9) ◽  
pp. H1143-H1153 ◽  
Author(s):  
Bart Spronck ◽  
Esther G. H. J. Martens ◽  
Erik D. Gommer ◽  
Frans N. van de Vosse
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Flow Control ◽  
Cerebral Autoregulation ◽  
Neurovascular Coupling ◽  
Flow Regulation ◽  
Lumped Parameter Model ◽  
Blood Flow Regulation ◽  
Lumped Parameter ◽  
Blood Flow Control

Cerebral blood flow regulation is based on a variety of different mechanisms, of which the relative regulatory role remains largely unknown. The cerebral regulatory system expresses two regulatory properties: cerebral autoregulation and neurovascular coupling. Since partly the same mechanisms play a role in cerebral autoregulation and neurovascular coupling, this study aimed to develop a physiologically based mathematical model of cerebral blood flow regulation combining these properties. A lumped parameter model of the P2 segment of the posterior cerebral artery and its distal vessels was constructed. Blood flow regulation is exerted at the arteriolar level by vascular smooth muscle and implements myogenic, shear stress based, neurogenic, and metabolic mechanisms. In eight healthy subjects, cerebral autoregulation and neurovascular coupling were challenged by squat-stand maneuvers and visual stimulation using a checkerboard pattern, respectively. Cerebral blood flow velocity was measured using transcranial Doppler, whereas blood pressure was measured by finger volume clamping. In seven subjects, the model proposed fits autoregulation and neurovascular coupling measurement data well. Myogenic regulation is found to dominate the autoregulatory response. Neurogenic regulation, although only implemented as a first-order mechanism, describes neurovascular coupling responses to a great extent. It is concluded that our single, integrated model of cerebral blood flow control may be used to identify the main mechanisms affecting cerebral blood flow regulation in individual subjects.

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