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Numerical study on flow topology and hemodynamics in tortuous coronary artery with symmetrical and asymmetrical stenosis

Song Jianfei, Kouidri Smaine, Bakir Farid

Biocybernetics and Biomedical Engineering

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2021

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Vol. 41, no. 1

142--155

EN

Tortuosity in coronary artery has been found to be greatly related to the potential sites of stenosis in these last years. Many investigations have been carried out based on the tool of Computational Fluid Dynamics (CFD) mainly focusing on the influences of curved artery in blood flow. Within the limited investigations of coupling between stenosis and tortuosity, the stenosis has been considered to be located at the tortuous segment. However, with recent clinical studies, the case of stenosis occurred at non-tortuous segment before tortuosities has been confirmed which has not been paid enough attention yet. Therefore, the present study aims to investigate the disturbed streamlines and hemodynamics in curved and spiral artery considering symmetrical and asymmetrical stenosis upstream these tortuosities. Different stenosis severities, pulse rates and distances between stenosis and tortuosity as controlling parameters have been studied. The distribution of time averaged wall shear stress (TAWSS) and streamlines through tortuous segment have been displayed in order to determine the potential disease sites. Artery surface of TAWSS below critical value has been quantified as well to evaluate the risks of atherosclerosis. The results reveal that larger artery surface of TAWSS below critical value generally goes with smaller pulse rate, larger stenosis severity and distance between stenosis and tortuosity both for curved and spiral artery. However, exceptions were found in the cases of distance of 6 mm in curved artery with symmetrical stenosis and stenosis severity of 50% in spiral artery. Moreover, the spiral tortuosity tends to suppress the potential risks of atherosclerosis compared to curved tortuosity.

2

Primary stenosis progression versus secondary stenosis formation in the left coronary bifurcation: A mechanical point of view

Jahromi Reza, Pakravan Hossein Ali, Saidi Mohammad Said, Firoozabadi Bahar

Biocybernetics and Biomedical Engineering

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2019

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Vol. 39, no. 1

188--198

EN

Biomechanical forces and hemodynamic factors influence the blood flow and the endothelial cells (ECs) morphology. These factors behave differently beyond the coronary artery stenosis. In the present study, unsteady blood flow in the left coronary artery (LCA) and its atherosclerotic bifurcating vessels, left anterior descending (LAD) and left circumflex (LCX) arteries, were numerically simulated to investigate the risk of plaque length development and secondary plaque formation in the post-stenotic areas. Using fluid–structure interaction (FSI) model, compliance of arterial wall and vessel curvature variations due to cardiac motion were considered. The arteries included plaques at the beginning of the bifurcation. Stenosis degree varied from 40% to 70% based on diameter reduction. Healthy coronary artery was also reconstructed to compare with the atherosclerotic arteries. Circumferential and longitudinal strains of ECs as well as wall shear stress (WSS) were computed in different locations downstream of the stenosis. It was concluded that the most critical regions experiencing low circumferential strain and low WSS were located proximal to the plaque throat, and the effects of these parameters intensified by stenosis degree. The results proposed that primary plaque length progression is more probable than secondary plaque formation distal to the stenosis when the stenosis degree increases.

3

Hemodynamic impacts of left coronary stenosis : a patient-specific analysis

Chaichana T., Sun Z., Jewkes J.

Acta of Bioengineering and Biomechanics

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2013

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Vol. 15, no. 3

107--111

EN

This study analyses the hemodynamic variations surrounding stenoses located at the left coronary bifurcation, and their influence on the wall shear stress (WSS) in realistic coronary geometries. Four patients with suspected coronary artery disease were chosen, and coronary models were reconstructed based on high-resolution CT data. The coronary stenoses were observed at the left circumflex and left anterior descending branches, resulting in a lumen narrowing of >50%. Flow analysis was performed using computational fluid dynamics, to simulate the cardiac flow conditions of the realistic individual patient geometry. Blood flow and WSS changes in the left coronary artery were calculated throughout the entire cardiac phases. Our results revealed that the recirculation regions were found at the poststenotic locations. WSS was found to increase at the stenotic positions in all four patients. There is a strong correlation between coronary stenosis and the hemodynamic changes, which are reflected in blood flow pattern and WSS, based on the realistic left coronary geometries.

4

Modelowanie przepływu krwi przez naczynie wieńcowe ze stentem

Kurowska-Nouyrigat W., Szumbarski J.

Aktualne Problemy Biomechaniki

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2009

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z. 3

115--120

PL

Jedną z popularniejszych nieinwazyjnych metod leczenia arteriosklerozy jest angioplastyka i implantacja stentów (na świecie około 1 min interwencji rocznie, z czego 60-80% ze stentem). Niestety, w 20-30% przypadków wprowadzeniu stentu towarzyszy powikłanie polegające na przeroście śródbłonka powodującym restenozę w przeciągu 3-6 miesięcy po implantacji. Stosując realistyczny, trójwymiarowej model geometryczny naczynia z implantowanym stentem, przeprowadzono analizę czynników geometrycznych i przepływowych ukazujące ich związek z rozwojem restenozy.

EN

Nowadays, cardiac disease are one of the most common cause of death. Each year almost one million of angioplasty interventions and stents implantations are made all over the world. Unfortunately, in 20-30% of cases neointimal proliferations leads to restenosis occurring within the following period of 3-6 months. The aim of the current research is to analyse how geometrical changes inflicted by the stent implantation affect the WSS distribution.

5

Grafowe techniki sztucznej inteligencji w percepcyjnej analizie przestrzennych zobrazowań tętnic wieńcowych

Ogiela M., Tadeusiewicz R., Trzupek M.

Acta Bio-Optica et Informatica Medica. Inżynieria Biomedyczna

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2005

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Vol. 11, nr 3-4

10-13

PL

W pracy omówiono sposoby wykorzystania technik inteligencji obliczeniowej, a zwłaszcza grafowych formalizmów lingwistycznych do tworzenia syntaktycznego opisu znaczeniowego przestrzennych wizualizacji naczyń wieńcowych serca. Opisy takie mogą być wykorzystywane w inteligentnych systemach wspomagania diagnostyki medycznej, ukierunkowanych na dokonywanie komputerowej interpretacji semantycznej poszczególnych części drzewa naczyń wieńcowych. Interpretacja taka pozwoli na szybką I w znacznym stopniu automatyczną detekcję miejsc istotnych przewężeń światła naczyń. W tym też celu wykorzystane zostały grafowe formalizmy obrazowe, oparte na gramatykach generujących IE grafy, które pozwalają na wykrywanie nieprawidłowości uwidocznionych na obrazach otrzymywanych w trakcie badań diagnostycznych mięśnia sercowego, z użyciem spiralnej tomografii komputerowej. Zaletą omawianych formalizmów obrazowych jest możliwość dokonywania automatycznej Identyfikacji miejsc zmian chorobowych, a także znaczeniowego opisu badanych rekonstrukcji przestrzennych naczyń wieńcowych.

EN

In this paper there will be described the way of application of computational intelligence techniques, and especially graph linguistic formalisms for creation syntactic meaning description of spatial coronary arteries structure. Such descriptions may be than used in intelligent medical diagnosis support systems, which will allow to make essentially steered semantic interpretation of sections coronary arteries morphology as well as fast Identification and automatisation of lumen stricture detection. In order to state a correct diagnosis and define the degree of pathological changes has been used graph image languages based on the expansive graph grammars of IE type. These kinds of grammars enable effective detection of abnormalities in diagnostic images obtained using spiral computerized tomography. An advantage of these Image languages Is automatic identification of changes essential from diagnostic point of view, and the introduction of semantic relations and description In reconstruction of analyzed coronary vessels.