Hemodynamic parameters and vessel tortuosity: an investigation with a mesenterial vascular network

Purpose: The effect of hemodynamic parameters on vessel tortuosity remains un-clear. Here we investigate the correlation of tortuosity with a set of hemodynamicparameters in a mesenterial vascular network.Methods: A mesenterial vascular network of 389 vessels (131 arteries, 132 veins, and 126 capillaries) was imaged. Eleven hemodynamic parameters were measured (pressure, wall shear stress, diameter, blood velocity and flow, viscosity, haematocrit, partial oxygen saturation, oxygen saturation, wall thickness, and local vessel density). Tortuosity was assessed quantitatively with a validated algorithm and correlation computed with subsets of hemodynamic parameters selected by a lasso regressor.Results: Results suggest that tortuosity is related to pressure, wall shear stress, diameter, blood velocity, viscosity, partial but not full oxygen saturation, and wall thickness for the arteries; diameter, blood flow, hematocrit, and density for the veins; and viscosity (but not hematocrit), partial and full oxygen saturation, and density for the capillaries. The combination of hemodynamic parameters correlating best with tortuosity is the set of all parameters except density (r = 0.64, p < 0.01), using as tortuosity definition the set of tortuosity features (geometric measures) correlating best with a single hemodynamic factor for the arteries.Conclusion: This pilot suggests two general conclusions. First, the quantitative definition of tortuosity (i.e., the set of geometric features adopted) should be tuned to the specific data and problem considered. Second, tortuosity is caused by a combination of hemodynamic factors, not a single one.

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P3588The synergistic effect of NIRS-detected lipid-rich plaque and 5 different multidirectional wall shear stress metrics on human coronary plaque growth

European Heart Journal ◽

10.1093/eurheartj/ehz745.0448 ◽

2019 ◽

Vol 40 (Supplement_1) ◽

Author(s):

E M J Hartman ◽

A M Kok ◽

A Hoogendoorn ◽

F J H Gijsen ◽

A F W Steen ◽

...

Keyword(s):

Shear Stress ◽

Wall Shear Stress ◽

Synergistic Effect ◽

Coronary Arteries ◽

Wall Thickness ◽

Plaque Progression ◽

Lipid Rich Plaque ◽

Plaque Growth ◽

Wall Shear ◽

The Impact

Abstract Introduction Local wall shear stress (WSS) metrics, high local lipid levels (as detected by near-infrared spectroscopy (NIRS)), as well as systemic lipid levels, have been individually associated with atherosclerotic disease progression. However, a possible synergistic effect remains to be elucidated. This study is the first study to combine WSS metrics with NIRS-detected local lipid content to investigate a potential synergistic effect on plaque progression in human coronary arteries. Methods The IMPACT study is a prospective, single centre study investigating the relation between atherosclerotic plaque progression and WSS in human coronary arteries. Patients with ACS treated with PCI were included. At baseline and after 1-year follow-up, patients underwent near-infrared spectroscopy intravascular ultrasound (NIRS-IVUS) imaging and intravascular doppler flow measurements of at least one non-culprit coronary artery. After one month, a CT angiography was made. CT derived centreline combined with IVUS lumen contours resulted in a 3D reconstruction of the vessel. The following WSS metrics were computed using computational fluid dynamics applying the vessel specific invasive flow measurements: time-average wall shear stress (TAWSS), relative residence time (RRT), cross-flow index, oscillatory shear index and transverse wall shear stress. Low TAWSS is known as pro atherogenic, in contrast to all the other shear stress metrics, at which a high magnitude is pro-atherogenic. The arteries were divided into 1.5mm/45° sectors. Based on NIRS-IVUS, wall thickness change over time was determined and NIRS positive sectors detected. Furthermore, per vessel the shear stress was divided into tertiles (low, intermediate, high). To investigate the synergistic effect of local lipids on shear stress related plaque growth, wall thickness change over time was related to the different shear stress metrics comparing the NIRS-positive with the NIRS-negative sectors. Results 15 non-culprit coronary arteries from the first 14 patients were analyzed (age 62±10 years old and 92.9% male). A total of 2219 sectors were studied (5.2%, N=130, NIRS-positive) for wall thickness changes. After studying all five shear stress metrics, we found for TAWSS and RRT that presence of lipids, as detected by NIRS, amplified the effect of shear stress on plaque progression (see figure). Sectors presenting with lipid-rich plaque, compared to NIRS-negative sectors, showed more progression when they were exposed to low TAWSS (p=0.07) or high RRT (p=0.012) and more regression in sectors exposed to high TAWSS (p=0.10) or low RRT (p=0.06). Delta wall thickness vs shear stress Conclusion We presented the first preliminary results of the IMPACT study, showing the synergistic effect of lipid rich plaque and shear stress on plaque progression. Therefore, intravascular lipid-rich plaque (NIRS) assessment has added value to shear stress profiling for the prediction of plaque growth, leading to improved risk stratification. Acknowledgement/Funding ERC starting grant 310457

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

Journal of Biomechanical Engineering ◽

10.1115/1.4051923 ◽

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.

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Wall shear stress alterations at left atrium and left atrial appendage employing abnormal blood velocity profiles

2020 42nd Annual International Conference of the IEEE Engineering in Medicine & Biology Society (EMBC) ◽

10.1109/embc44109.2020.9175235 ◽

2020 ◽

Author(s):

Grigoris I. Grigoriadis ◽

Antonis I. Sakellarios ◽

Ioanna Kosmidou ◽

Katerina K. Naka ◽

Christopher Ellis ◽

...

Keyword(s):

Shear Stress ◽

Wall Shear Stress ◽

Left Atrium ◽

Left Atrial ◽

Left Atrial Appendage ◽

Velocity Profiles ◽

Blood Velocity ◽

Atrial Appendage ◽

Wall Shear

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Longitudinal Effect of Wall Shear Stress on the Amount of Intimal-Medial Thickening of Venous Wall in Arteriovenous Fistula

ASME 2012 Summer Bioengineering Conference, Parts A and B ◽

10.1115/sbc2012-80806 ◽

2012 ◽

Author(s):

Ehsan Rajabi-Jaghargh ◽

Prabir Roy-Chaudhury ◽

Mahesh K. Krishnamoorthy ◽

Yang Wang ◽

Rupak K. Banerjee

Keyword(s):

Shear Stress ◽

Wall Shear Stress ◽

Arteriovenous Fistula ◽

Hemodynamic Parameters ◽

Temporal Gradient ◽

Post Surgery ◽

Venous Stenosis ◽

Venous Diameter ◽

Consistent Increase ◽

Wall Shear

Arteriovenous fistula (AVF) maturation failure is mainly due to venous stenosis characterized by significant amount of intima-media thickening (IMT). Although hemodynamic endpoints are believed to play a crucial role in pathogenesis of venous stenosis, the exact mechanism behind this is unclear. Our hypothesis is that longitudinal (temporal) changes of hemodynamic parameters, specifically wall shear stress (WSS), influences amount of IMT in maturation process of AVF. AVFs were created in curved (C-AVF) and straight (S-AVF) configurations between femoral artery and vein of 3 pigs. CT-scans and ultrasound were utilized to calculate WSS at 2D (D: days), 7D, and 28D post-surgery. IMT was measured at 4 histological blocks along the vein of AVFs. It was found that C-AVF underwent outward remodeling characterized by consistent increase in venous diameter and larger IMT. This remodeling process was governed by negative temporal gradient of WSS (τ′) [−0.99 ± 0.60 dyn/cm2/day]. In contrast, S-AVF underwent inward remodeling characterized by temporal decrease in venous diameter and relatively smaller IMT. This remodeling process was governed by positive τ′ (0.42 ± 0.6 dyn/cm2/day). In summary, temporal gradient of WSS influences IMT. Temporal decrease of WSS in C-AVF resulted in vasodilation and outward growth of wall (favorable to maturation). However, temporal increase in WSS in S-AVF leaded to vasoconstriction and inward growth of wall (detrimental to maturation). Thus, clinically it can be of great importance to surgeons to create AVF in a configuration that can result in favorable hemodynamic parameters and histological end-points.

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Developing Pulsatile Flow in a Deployed Coronary Stent

Journal of Biomechanical Engineering ◽

10.1115/1.2194067 ◽

2005 ◽

Vol 128 (3) ◽

pp. 347-359 ◽

Cited By ~ 19

Author(s):

Divakar Rajamohan ◽

Rupak K. Banerjee ◽

Lloyd H. Back ◽

Ashraf A. Ibrahim ◽

Milind A. Jog

Keyword(s):

Shear Stress ◽

Wall Shear Stress ◽

Pulsatile Flow ◽

Thrombus Formation ◽

Three Dimensional ◽

Tissue Growth ◽

Coronary Stent ◽

Stress Distributions ◽

Hemodynamic Parameters ◽

Wall Shear

A major consequence of stent implantation is restenosis that occurs due to neointimal formation. This patho-physiologic process of tissue growth may not be completely eliminated. Recent evidence suggests that there are several factors such as geometry and size of vessel, and stent design that alter hemodynamic parameters, including local wall shear stress distributions, all of which influence the restenosis process. The present three-dimensional analysis of developing pulsatile flow in a deployed coronary stent quantifies hemodynamic parameters and illustrates the changes in local wall shear stress distributions and their impact on restenosis. The present model evaluates the effect of entrance flow, where the stent is placed at the entrance region of a branched coronary artery. Stent geometry showed a complex three-dimensional variation of wall shear stress distributions within the stented region. Higher order of magnitude of wall shear stress of 530dyn∕cm2 is observed on the surface of cross-link intersections at the entrance of the stent. A low positive wall shear stress of 10dyn∕cm2 and a negative wall shear stress of −10dyn∕cm2 are seen at the immediate upstream and downstream regions of strut intersections, respectively. Modified oscillatory shear index is calculated which showed persistent recirculation at the downstream region of each strut intersection. The portions of the vessel where there is low and negative wall shear stress may represent locations of thrombus formation and platelet accumulation. The present results indicate that the immediate downstream regions of strut intersections are areas highly susceptible to restenosis, whereas a high shear stress at the strut intersection may cause platelet activation and free emboli formation.

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Combined Visualization of Wall Thickness and Wall Shear Stress for the Evaluation of Aneurysms

IEEE Transactions on Visualization and Computer Graphics ◽

10.1109/tvcg.2014.2346406 ◽

2014 ◽

Vol 20 (12) ◽

pp. 2506-2515 ◽

Cited By ~ 11

Author(s):

Sylvia Glasser ◽

Kai Lawonn ◽

Thomas Hoffmann ◽

Martin Skalej ◽

Bernhard Preim

Keyword(s):

Shear Stress ◽

Wall Shear Stress ◽

Wall Thickness ◽

Wall Shear

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Sensitivity of Hemodynamic Parameters to Waveform, Flow Division, and Head Rotation in the Human Carotid Bifurcation

ASME 2008 Summer Bioengineering Conference, Parts A and B ◽

10.1115/sbc2008-189696 ◽

2008 ◽

Author(s):

Yannis Papaharilaou ◽

Ioannis Seimenis ◽

John Ekaterinaris ◽

Georgios Georgiou ◽

Eleni Eracleous ◽

...

Keyword(s):

Shear Stress ◽

Wall Shear Stress ◽

Head Rotation ◽

Carotid Bifurcation ◽

Hemodynamic Parameters ◽

Flow Waveform ◽

Temporal Gradient ◽

Wall Shear ◽

Flow Division ◽

Human Carotid

Hemodynamic parameters such as time averaged wall shear stress (TAWSS), wall shear stress temporal gradient (WSSTG) and Oscillatory Shear Index (OSI) have previously been cited as parameters associated with the development of atherosclerotic disease at the human carotid bifurcation [1,2]. The sensitivity of these important parameters however, with variations of driving flow waveform, flow division and posture changes are not well known. To investigate these changes, we have used image based CFD, to analyze the flowfield of the carotid bifurcation of a healthy volunteer for five different input waveforms, three flow division ratios and two head postures.

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Negative Correlation of Wall Thickness With Wall Blood Pressure in a Patient-Specific Atherosclerotic Coronary Artery: A Case Report

ASME 2012 Summer Bioengineering Conference, Parts A and B ◽

10.1115/sbc2012-80039 ◽

2012 ◽

Author(s):

Biyue Liu ◽

Jie Zheng ◽

Richard Bach ◽

Dalin Tang

Keyword(s):

Blood Pressure ◽

Shear Stress ◽

Wall Shear Stress ◽

Wall Thickness ◽

Patient Specific ◽

Artery Wall ◽

Atherosclerosis Progression ◽

Wall Shear ◽

Intensive Investigation ◽

The Impact

There are two major hemodynamic stresses imposed at the blood-arterial wall interface by flowing blood: the wall shear stress (WSS) acting tangentially to the wall, and the wall pressure (WP) acting vertically to the wall. These forces influence the artery wall metabolism and correspond to the local modifications of artery wall thickness, composition, microarchitecture, and compliance [2]. The role of flow wall shear stress in atherosclerosis progression has been under intensive investigation [4], while the impact of local blood pressure on plaque progression has been under-studied.

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