scholarly journals Effect of Viscoelasticity on Arterial-Like Pulsatile Flow Dynamics and Energy

2019 ◽  
Vol 142 (4) ◽  
Author(s):  
Winston Elliott ◽  
Dongjie Guo ◽  
Gruschen Veldtman ◽  
Wei Tan
Keyword(s):  
Pulsatile Flow ◽  
Arterial Wall ◽  
Cardiac Cycle ◽  
Circulatory System ◽  
Time Dependent ◽  
Cross Sectional ◽  
Disease Prognosis ◽  
Wall Property ◽  
Flow Pressure ◽  
Wall Shear

Abstract Time-dependent arterial wall property is an important but difficult topic in vascular mechanics. Hysteresis, which appears during the measurement of arterial pressure–diameter relationship through a cardiac cycle, has been used to indicate time-dependent mechanics of arteries. However, the cause–effect relationship between viscoelastic (VE) properties of the arterial wall and hemodynamics, particularly the viscous contribution to hemodynamics, remains challenging. Herein, we show direct comparisons between elastic (E) (loss/storage < 0.1) and highly viscoelastic (loss/storage > 0.45) conduit structures with arterial-like compliance, in terms of their capability of altering pulsatile flow, wall shear, and energy level. Conduits were made from varying ratio of vinyl- and methyl-terminated poly(dimethylsiloxane) and were fit in a mimetic circulatory system measuring volumetric flow, pressure, and strain. Results indicated that when compared to elastic conduits, viscoelastic conduits attenuated lumen distension waveforms, producing an average of 11% greater cross-sectional area throughout a mimetic cardiac cycle. In response to such changes in lumen diameter strain, pressure and volumetric flow waves in viscoelastic conduits decreased by 3.9% and 6%, respectively, in the peak-to-peak amplitude. Importantly, the pulsatile waveforms for both diameter strain and volumetric flow demonstrated greater temporal alignment in viscoelastic conduits due to pulsation attenuation, resulting in 25% decrease in the oscillation of wall shear stress (WSS). We hope these findings may be used to further examine time-dependent arterial properties in disease prognosis and progression, as well as their use in vascular graft design.

A Review On the Effect of Temporal Geometric Variations of the Coronary Arteries On the Wall Shear Stress and Pressure Drop

2021 ◽  
Author(s):  
Navid Freidoonimehr ◽  
Rey Chin ◽  
Anthony C. Zander ◽  
Maziar Arjomandi
Keyword(s):  
Shear Stress ◽  
Pressure Drop ◽  
Wall Shear Stress ◽  
Coronary Arteries ◽  
Cardiac Cycle ◽  
Temporal Variations ◽  
Hemodynamic Parameters ◽  
Clinical Environment ◽  
Cross Sectional ◽  
Wall Shear

Abstract Temporal variations of the coronary arteries during a cardiac cycle are defined as the superposition of the changes in the position, curvature, and torsion of the coronary artery axis markers and the variations in the lumen cross-sectional shape due to the distensible wall motion induced by the pulse pressure and contraction of the myocardium in a cardiac cycle. This review discusses whether the modelling the temporal variations of the coronary arteries is needed for the investigation of the hemodynamics specifically in time critical applications such as a clinical environment. The numerical modellings in the literature which model or disregard the temporal variations of the coronary arteries on the hemodynamic parameters are discussed. The results in the literature show that neglecting the effects of temporal geometric variations is expected to result in about 5\% deviation of the time-averaged pressure drop and wall shear stress values and also about 20\% deviation of the temporal variations of hemodynamic parameters, such as time-dependent wall shear stress and oscillatory shear index. This review study can be considered as a guide for the future studies to outline the conditions in which temporal variations of the coronary arteries can be neglected, while providing a reliable estimation of hemodynamic parameters.

Dynamics of the right atrio-ventricular junction in human: a spatial high-resolution study with multiphase computed tomography

2020 ◽  
Vol 41 (Supplement_2) ◽  
Author(s):  
J Jouan ◽  
I Masari ◽  
V Bliah ◽  
G Soulat ◽  
D Craiem ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Cardiac Cycle ◽  
Cardiac Computed Tomography ◽  
Reconstruction Method ◽  
Imaging Data ◽  
High Definition ◽  
Vertical Projection ◽  
Horizontal Projection ◽  
Cross Sectional ◽  
The Right

Abstract Introduction In order to improve knowledge of the tricuspid valve (TV) function and its coupling with the right atrio-ventricular junction (RAVJ) and right ventricle (RV), new four-dimensional high-definition imagery methods are mandatory (3D+t). Purpose Using an innovative reconstruction method based on multiphase cardiac computed tomography imaging (4D-MCCTI), we finely analyzed the morphological & dynamical features of tricuspid annulus (TA) and RAVJ components in order to assess new functional parameters of TV and RV functions. Methods Volume imaging data sets through time were obtained from 4D-MCCTI of 30 subjects (sex ratio 1, mean age 57±11y.) with no rhythm, valvular or ventricular abnormalities on echocardiography and implemented in a custom software for 3D semi-automated delineation of 18 points around TA perimeter. Coordinates of these points in each of the 10 time-phases within an RR interval were used to calculate specific geometrical features of TA such as 3D/2D areas, perimeters, 360°-diameters and vertical deformation. Subsequently, RV and Right Atrium (RA) inner contours were also delineated (Figure). Results TA shape was elliptical in horizontal projection with a mean eccentricity index (EcI) of 0.58±0.12; and saddle-shapped in vertical projection with a horn nearby the antero-septal commissure. This feature remained throughout the cardiac cycle but TA was more planar (minimal TA-height: 4.47±1.04 mm) and circular (minimal EcI=0.44±0.14) in mid-diastole when TA-3Darea and TA-3Dperimeter reached a maximum of 6.98±1.21 cm2/m2 and 7.41±0.91 cm, respectively. Correlation between TA-3Darea, TA-2Darea and latero-septal diameter (LSD) were R2=0.99 and R2=0.73, respectively. LSD was minimal in early-systole (18.83±3.04 mm/m2) and maximal in mid-diastole (20.04±3.05 mm/m2). Correlation of TA-3Darea with RV and RA cross-sectional areas were R2=0.82 and R2=0.71, respectively. Conversely, there was no significant correlation between TA, RV and RA concentric contractions. Conclusions Our method for 4D-MTCCI analysis has allowed confirming the shape and dynamics function of RAVJ throughout the cardiac cycle in healthy subjects, and giving new reference parameters for TV and RV evaluation. Software multiplanar view of TA Funding Acknowledgement Type of funding source: None

scholarly journals Linking cardiorespiratory fitness classification criteria to early subclinical atherosclerosis in children

2015 ◽  
Vol 40 (4) ◽  
pp. 386-392 ◽  
Author(s):  
Xavier Melo ◽  
Helena Santa-Clara ◽  
Diana A. Santos ◽  
Nuno M. Pimenta ◽  
Cláudia S. Minderico ◽  
...  
Keyword(s):  
Cardiorespiratory Fitness ◽  
Arterial Wall ◽  
Operating Characteristic ◽  
Screening Tool ◽  
Subclinical Atherosclerosis ◽  
Intima Media Thickness ◽  
Carotid Intima Media Thickness ◽  
Cross Sectional Study ◽  
Cross Sectional ◽  
High Resolution Ultrasonography

It is unclear if cardiorespiratory fitness (CRF) can be used as a screening tool for premature changes in carotid intima-media thickness (cIMT) in paediatric populations. The purpose of this cross-sectional study was 3-fold: (i) to determine if CRF can be used to screen increased cIMT; (ii) to determine an optimal CRF cut-off to predict increased cIMT; and (iii) to evaluate its ability to predict increased cIMT among children in comparison with existent CRF cut-offs. cIMT was assessed with high-resolution ultrasonography and CRF was determined using a maximal cycle test. Receiver operating characteristic analyses were conducted in boys (n = 211) and girls (n = 202) aged 11–12 years to define the optimal sex-specific CRF cut-off to classify increased cIMT (≥75th percentile). Logistic regression was used to examine the association between the CRF cut-offs with the risk of having an increased cIMT. The optimal CRF cut-offs to predict increased cIMT were 45.81 and 34.46 mL·kg−1·min−1 for boys and girls, respectively. The odds-ratios for having increased cIMT among children who were unfit was up to 2.8 times the odds among those who were fit (95% confidence interval: 1.40–5.53). Considering current CRF cut-offs, only those suggested by Adegboye et al. 2011. (Br. J. Sports Med. 45(9): 722–728) and Boddy et al. 2012 (PLoS One, 7(9): e45755) were significant in predicting increased cIMT. In conclusion, CRF cut-offs (boys: ≤ 45.8; girls: ≤ 34.5 mL·kg−1·min−1) are associated with thickening of the arterial wall in 11- to 12-year-old children. Low CRF is an important cardiovascular risk factor in children and our data highlight the importance of obtaining an adequate CRF.

HUBUNGAN INTENSITAS KEBISINGAN DENGAN TEKANAN DARAH PADA PEKERJA AREA WORKSHOP

2020 ◽  
Vol 9 (1) ◽  
pp. 18-26
Author(s):  
Mariman Tjendera ◽  
Isramilda Isramilda
Keyword(s):  
Blood Pressure ◽  
Noise Intensity ◽  
Circulatory System ◽  
Sampling Technique ◽  
Strong Relationship ◽  
Normal Blood ◽  
Normal Blood Pressure ◽  
Exclusion Criteria ◽  
Cross Sectional ◽  
Stage 1

Noise in the workplace is often a separate problem for the workforce so that it can cause mental-emotional disturbance as well as the heart and circulatory system. According to the 2013 Basic Health Research, the prevalence of high blood pressure in Indonesia at the age of ≥18 years is 25.8%. So the researchers wanted to find a relationship between noise intensity and blood pressure. This research method was observational analytic with a cross-sectional approach conducted at PT. Bintang Intipersada Shipyard, Batam City. The sampling technique was a total sampling with a population of 100 workers in 2018 and obtained results of 61 workers determined by inclusion and exclusion criteria. The results of the study were analyzed with a frequency distribution tabulated and tested with the Pearson Product Moment Test. The results of this study worker who were exposed to noise intensity ≤85 dBA had a normal blood pressure of 8 (36.5%) people, in workers who were exposed to noise intensity ≤85 dBA had blood pressure with Pre-hypertension as many as 12 (54.5% ) people, for workers exposed to noise intensity ≤85 dBA have 1 (4.5%) blood pressure with Stage 1 Hypertension, workers who are exposed to noise intensity ≤85 dBA have blood pressure with Stage 2 Hypertension as much as 1 (4.5 %) person. While workers who are exposed to noise intensity> 85 dBA have normal blood pressure of 0 (0%) people, workers who are exposed to noise intensity> 85 dBA have blood pressure with Pre-hypertension as much as 2 (5.1%) people, workers are exposed to noise intensity> 85 dBA had blood pressure with Stage 1 Hypertension as many as 14 (35.9%) people, then workers exposed to noise intensity> 85 dBA had blood pressure with Stage 2 Hypertension as many as 23 (59%) workers. The results of the Pearson Product Moment analysis value of p = 0,000 <α 0.05, there is a relationship between noise intensity and blood pressure with the magnitude of the correlation coefficient (r) which is 0.795 meaning, there is a strong relationship. Based on this study it can be concluded that there is a significant relationship between noise intensity and blood pressure.

scholarly journals The Relationship of Lifestyle with Hypertension Incidence in Antang Public Health Center of Makassar City

2020 ◽  
Vol 2020 ◽  
Author(s):  
Agussalim
Keyword(s):  
Public Health ◽  
Blood Pressure ◽  
Health Center ◽  
Health Workers ◽  
Circulatory System ◽  
Simple Random Sampling ◽  
Bivariate Analysis ◽  
Cross Sectional ◽  
Public Health Center ◽  
The Relationship

Hypertension is a disease that usually occurs in the circulatory system which can cause an increase in blood pressure above the normal value, which exceeds 140/90 mmHg. The intention of this study aims to understand the relationship between lifestyle and the incidence of hypertension in Antang Makassar Public Health Center in 2018. This research method uses quantitative analytic motives using a cross sectional approach with a population of 46 people and a sample of 36 respondents. This research was conducted on July 14-16 June. The method used is simple random sampling and the tool used to obtain data is a questionnaire. The scale used is Liker and Guttmann scale with univariate, bivariate analysis and chi-square test with significant a = 0, 05. The results of this study indicate there is a relationship between lifestyle and the incidence of hypertension in the Makassar Antang Health Center with P = 0, 01 smaller than the value of a = 0.05. Suggestions are for hypertensive patients, namely the need to check their health routinely to health workers in order to know the development of blood pressure and obtain information from health workers.

scholarly journals Effect of Pulsatile Flow Waveform and Womersley Number on the Flow in Stenosed Arterial Geometry

2012 ◽  
Vol 2012 ◽  
pp. 1-17 ◽  
Author(s):  
Moloy Kumar Banerjee ◽  
Ranjan Ganguly ◽  
Amitava Datta
Keyword(s):  
Pulsatile Flow ◽  
Physiological State ◽  
Circulatory System ◽  
The Body ◽  
Arterial System ◽  
Hemodynamic Parameters ◽  
Flow Waveform ◽  
Womersley Number ◽  
Flow Features ◽  
Hemodynamic Flow

The salient hemodynamic flow features in a stenosed artery depend not only on the degree of stenosis, but also on its location in the circulatory system and the physiological condition of the body. The nature of pulsatile flow waveform and local Womersley number vary in different regions of the arterial system and at different physiological state, which affects the local hemodynamic wall parameters, for example, the wall shear stress (WSS) and oscillatory shear index (OSI). Herein, we have numerically investigated the effects of different waveforms and Womersley numbers on the flow pattern and hemodynamic parameters in an axisymmetric stenosed arterial geometry with 50% diametral occlusion. Temporal evolution of the streamlines and hemodynamic parameters are investigated, and the time-averaged hemodynamic wall parameters are compared. Presence of the stenosis is found to increase the OSI of the flow even at the far-downstream side of the artery. At larger Womersley numbers, the instantaneous flow field in the stenosed region is found to have a stronger influence on the flow profiles of the previous time levels. The study delineates how an approximation in the assumption of inlet pulsatility profile may lead to significantly different prediction of hemodynamic wall parameters.

scholarly journals Survey on Zoonotic Importance and Prevalence of Dirofilaria immitis Infection in Dogs of Tabriz, Iran

2020 ◽  
Vol 1 (1) ◽  
pp. 11-13
Author(s):  
Hossein Hashemzadeh Farhang ◽  
Seyed Razi Bahavarnia ◽  
Mohamad Javad Esmailzadeh ◽  
Navid Mahmoudi Kamalabad
Keyword(s):  
Dirofilaria Immitis ◽  
Circulatory System ◽  
Cross Sectional Study ◽  
Sectional Study ◽  
Cross Sectional ◽  
Comprehensive Examination ◽  
And Gender ◽  
One Year ◽  
Statistical Survey ◽  
And Control

Background: Dirofilaria immitis is one of the most important parasites of the circulatory system of dogs that causes severe cardiovascular events in the animal and it is reported to be the most common nematode in humans and dogs from many parts of Iran. Methods: In order to investigate the presence of Dirofilaria immitis infection in Tabriz, Iran, a cross-sectional study was performed on 200 owned and stray dogs. The blood samples were analyzed using Knott method. The prevalence of D. immitis infection was reported to be 15% in owned dogs. Results: The highest levels of infection were reported in dogs less than one year of age and the lowest in dogs aged over 9 years. In a statistical survey, there was a significant relationship between infection and gender. Conclusion: According to the findings of this study, due to the presence of D. immitis infection in this region, the need for a more comprehensive examination and control of the infection in this region is emphasized.

Cross-Sectional Elastic Imaging of Arterial Wall Using Intravascular Ultrasonography

2001 ◽  
Vol 40 (Part 1, No. 7) ◽  
pp. 4753-4762 ◽  
Author(s):  
Hitoshi Mita ◽  
Hiroshi Kanai ◽  
Yoshiro Koiwa ◽  
Masataka Ichiki ◽  
Fumiaki Tezuka
Keyword(s):  
Arterial Wall ◽  
Intravascular Ultrasonography ◽  
Cross Sectional
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