scholarly journals Blood Flow Modeling in Coronary Arteries: A Review

Fluids ◽  
2021 ◽  
Vol 6 (2) ◽  
pp. 53
Author(s):  
Violeta Carvalho ◽  
Diana Pinho ◽  
Rui A. Lima ◽  
José Carlos Teixeira ◽  
Senhorinha Teixeira
Keyword(s):  
Blood Flow ◽  
Coronary Arteries ◽  
High Performance ◽  
Computational Techniques ◽  
Cerebral Stroke ◽  
Numerical Studies ◽  
Viscosity Models ◽  
Blood Flow Modeling ◽  
Myocardium Infarction ◽  
Other Substances

Atherosclerosis is one of the main causes of cardiovascular events, namely, myocardium infarction and cerebral stroke, responsible for a great number of deaths every year worldwide. This pathology is caused by the progressive accumulation of low-density lipoproteins, cholesterol, and other substances on the arterial wall, narrowing its lumen. To date, many hemodynamic studies have been conducted experimentally and/or numerically; however, this disease is not yet fully understood. For this reason, the research of this pathology is still ongoing, mainly, resorting to computational methods. These have been increasingly used in biomedical research of atherosclerosis because of their high-performance hardware and software. Taking into account the attempts that have been made in computational techniques to simulate realistic conditions of blood flow in both diseased and healthy arteries, the present review aims to give an overview of the most recent numerical studies focused on coronary arteries, by addressing the blood viscosity models, and applied physiological flow conditions. In general, regardless of the boundary conditions, numerical studies have been contributed to a better understanding of the development of this disease, its diagnosis, and its treatment.

Numerical Study of Purely Viscous Non-Newtonian Flow in an Abdominal Aortic Aneurysm

2014 ◽  
Vol 136 (10) ◽  
Author(s):  
Victor L. Marrero ◽  
John A. Tichy ◽  
Onkar Sahni ◽  
Kenneth E. Jansen
Keyword(s):  
Blood Flow ◽  
Abdominal Aortic Aneurysm ◽  
Shear Rate ◽  
Aortic Aneurysm ◽  
Computational Techniques ◽  
Newtonian Viscosity ◽  
Viscosity Models ◽  
Newtonian Model ◽  
Abdominal Aortic ◽  
Newtonian Case

It is well known that blood has non-Newtonian properties, but it is generally accepted that blood behaves as a Newtonian fluid at shear rates above 100 s−1. However, in transient conditions, there are times and locations where the shear rate is well below 100 s−1, and it is reasonable to infer that non-Newtonian effects could become important. In this study, purely viscous non-Newtonian (generalized Newtonian) properties of blood are incorporated into the simulation-based framework for cardiovascular surgery planning developed by Taylor et al. (1999, “Predictive Medicine: Computational Techniques in Therapeutic Decision Making,” Comput. Aided Surg., 4, pp. 231–247; 1998, “Finite Element Modeling of Blood Flow in Arteries,” Comput. Methods Appl. Mech. Eng., 158, pp. 155–196). Equations describing blood flow are solved in a patient-based abdominal aortic aneurysm model under steady and physiological flow conditions. Direct numerical simulation (DNS) is used, and the complex flow is found to be constantly transitioning between laminar and turbulent in both the spatial and temporal sense. It is found for the case simulated that using the non-Newtonian viscosity modifies the solution in subtle ways that yield a mesh-independent solution with fewer degrees of freedom than the Newtonian counterpart. It appears that in regions of separated flow, the lower shear rate produces higher viscosity with the non-Newtonian model, which reduces the associated resolution needs. When considering the real case of pulsatile flow, high shear layers lead to greater unsteadiness in the Newtonian case relative to the non-Newtonian case. This, in turn, results in a tendency for the non-Newtonian model to need fewer computational resources even though it has to perform additional calculations for the viscosity. It is also shown that both viscosity models predict comparable wall shear stress distribution. This work suggests that the use of a non-Newtonian viscosity models may be attractive to solve cardiovascular flows since it can provide simulation results that are presumably physically more realistic with at least comparable computational effort for a given level of accuracy.

Study on Micro Piezoelectric Actuator by Using Longitudinal Wave Energy for Catheter Application

2010 ◽  
Author(s):  
M. Ajoudanian ◽  
M. Morita ◽  
Z. Jiang
Keyword(s):  
Blood Flow ◽  
Longitudinal Wave ◽  
High Performance ◽  
Blood Clot ◽  
Brain Cell ◽  
The Other ◽  
Cerebral Stroke ◽  
Cell Necrosis ◽  
Fundamental Study ◽  
Aged People

The cerebral stroke is one of the diseases which many aged people are being to suffer. It occurs due to a thrombus created in a blood vessel, which blocks a blood flow in a brain and induces a brain cell necrosis. This study is the part of a research project that aims to develop high performance and amplitude micro stirrer for dissolution of cerebral thrombus. This paper presents the fundamental study on of a Novel actuator for creating vertically fluctuation to effective dissolution of cerebral thrombus or blood clot. By stirring the blood around the thrombus after the infusion of the agent, the quick dissolution can be obtained. This actuator was supported one side and the other side is free. The longitudinal wave excited by transducer from support side, traveling throw catheter and before reach to tip of beam impinges to skewed surface and reflect to shear wave and longitudinal wave. Thus the stirrer moves transversely due to transverse wave and reflected longitudinal wave.

METHODOLOGICAL ASPECTS OF VISUALIZATION OF CORONARY ARTERIES WITH TRANSTHORACIC ECHOCARDIOGRAPHY

2018 ◽  
pp. 26-35
Author(s):  
Z. A. Agaeva ◽  
K. B. Baghdasaryan
Keyword(s):  
Blood Flow ◽  
Coronary Blood Flow ◽  
Coronary Arteries ◽  
Transthoracic Echocardiography ◽  
Second Harmonic ◽  
Anatomic Reconstruction ◽  
High Quality ◽  
Acoustic Window ◽  
Methodological Aspects

The transthoracic echocardiography made by multifrequency probes with support of the mode of the second harmonic imaging, is a competitive method for visualization of the main coronary arteries and allows to estimate coronary blood flow with high quality. Of course, the method has considerable restrictions, most important of which is the low spatial resolution of a method, due to small acoustic window. Because of this the transthoracic visualization of coronary arteries perhaps will not become the leading method of anatomic reconstruction of separately taken coronary artery and especially all coronary arteries system. However uniqueness and indisputable advantage of this method is an opportunity to noninvasively estimate a coronary blood flow both once, and in dynamics.

scholarly journals Calculating the optimal hematocrit under the constraint of constant cardiac power

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Michal Sitina ◽  
Heiko Stark ◽  
Stefan Schuster
Keyword(s):  
Blood Flow ◽  
High Performance ◽  
Animal Species ◽  
Normal Values ◽  
Mechanical Load ◽  
The Body ◽  
Trade Off ◽  
Cardiac Power ◽  
Optimal Value ◽  
Good Agreement

AbstractIn humans and higher animals, a trade-off between sufficiently high erythrocyte concentrations to bind oxygen and sufficiently low blood viscosity to allow rapid blood flow has been achieved during evolution. Optimal hematocrit theory has been successful in predicting hematocrit (HCT) values of about 0.3–0.5, in very good agreement with the normal values observed for humans and many animal species. However, according to those calculations, the optimal value should be independent of the mechanical load of the body. This is in contradiction to the exertional increase in HCT observed in some animals called natural blood dopers and to the illegal practice of blood boosting in high-performance sports. Here, we present a novel calculation to predict the optimal HCT value under the constraint of constant cardiac power and compare it to the optimal value obtained for constant driving pressure. We show that the optimal HCT under constant power ranges from 0.5 to 0.7, in agreement with observed values in natural blood dopers at exertion. We use this result to explain the tendency to better exertional performance at an increased HCT.

Fast CT-FFR Analysis Method for the Coronary Artery Based on 4D-CT Image Analysis and Structural and Fluid Analysis

2015 ◽  
Author(s):  
Mitsuaki Kato ◽  
Kenji Hirohata ◽  
Akira Kano ◽  
Shinya Higashi ◽  
Akihiro Goryu ◽  
...  
Keyword(s):  
Blood Flow ◽  
Coronary Artery ◽  
Boundary Conditions ◽  
Coronary Arteries ◽  
Computational Time ◽  
Ct Image ◽  
Analysis Method ◽  
Fractional Flow ◽  
4D Ct ◽  
Fluid Analysis

Non invasive fractional flow reserve derived from CT coronary angiography (CT-FFR) has to date been typically performed using the principles of computational fluid analysis in which a lumped parameter coronary vascular bed model is assigned to represent the impedance of the downstream coronary vascular networks absent in the computational domain for each coronary outlet. This approach may have a number of limitations. It may not account for the impact of the myocardial contraction and relaxation during the cardiac cycle, patient-specific boundary conditions for coronary artery outlets and vessel stiffness. We have developed a novel approach based on 4D-CT image tracking (registration) and structural and fluid analysis based on one dimensional mechanical model, to address these issues. In our approach, we analyzed the deformation variation of vessels and the volume variation of vessels to better define boundary conditions and stiffness of vessels. We focused on the blood flow and vessel deformation of coronary arteries and aorta near coronary arteries in the diastolic cardiac phase from 70% to 100 %. The blood flow variation of coronary arteries relates to the deformation of vessels, such as expansion and contraction of the cross-sectional area, during this period where resistance is stable, pressure loss is approximately proportional to flow. We used a statistical estimation method based on a hierarchical Bayes model to integrate 4D-CT measurements and structural and fluid analysis data. Under these analysis conditions, we performed structural and fluid analysis to determine pressure, flow rate and CT-FFR. Furthermore, the reduced-order model based on fluid analysis was studied in order to shorten the computational time for 4D-CT-FFR analysis. The consistency of this method has been verified by a comparison of 4D-CT-FFR analysis results derived from five clinical 4D-CT datasets with invasive measurements of FFR. Additionally, phantom experiments of flexible tubes with and without stenosis using pulsating pumps, flow sensors and pressure sensors were performed. Our results show that the proposed 4D-CT-FFR analysis method has the potential to accurately estimate the effect of coronary artery stenosis on blood flow.

Sign in / Sign up

Export Citation Format

Share Document