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The hemodynamic investigation of the abnormalities present at the arterial wall can be incorporated by employing various factors. In this work, the three-dimensional computational model of coronary artery procured from CT/MRI data of healthy patients is simulated. A comparative study is performed with a variating degree of stenosis based on hemodynamic factors. The blood is regarded as incompressible non-Newtonian Carreau fluid. Furthermore, the finite volume method (FVM) is implemented to solve the discretized mathematical equations and obtain a numerical solution. Wall shear stress (WSS), wall pressure gradient (WPG), and oscillatory shear index (OSI) play an eminent part in concluding the level of atherosclerotic plaque existence and hence these are discussed in this work. It is observed that the most diseased artery acquired the peak value of 3.63Pa of WSS, at the blocked region. The maximal notable WPG range is 9000 to 39 000N/m³, corresponding to the artery with the highest level of stenosis at mid-systole. The OSI contours reflected the oscillatory behavior of WSS and inherited the values between 0 and 0.4. Results derived from the present numerical solution indicate that high–low WSS and WPG can be strongly linked to atherosclerosis plaque existence. In this study, we analyze the comparative hemodynamic investigation of blood flow in different blocked models of 3D realistic coronary arteries under the same boundary conditions. This makes it a novel work in cardiovascular disease.

Percutaneous transluminal coronary angioplasty (PTCA) is a minimally invasive surgery in the clinical treatment of coronary artery diseases. The successful operation highly depends on the size and accurate placement of the stent. In this study, a virtual stenting (VS) system was designed and implemented to facilitate the planning of PTCA. A three-dimensional (3D) vessel model was reconstructed through fusing intravascular ultrasound (IVUS) sequential images and simultaneously recorded X-ray angiograms during cardiac intervention. The user is allowed to intuitively explore the vessel in an endoscopic manner by creating/updating a fly-through trajectory in the lumen. A virtual stent library including a better variety of commercially available bare metal heart stents was built. The user is allowed to select a proper stent according to the morphology of the vessel and lesion and to move it to the lesion. Also, the user can visually observe the stent expansion/apposition and flexibly adjust its position. The system is used to assist visual diagnosis of the vascular diseases, evaluation of interventional treatment and training of the medical personnel.

The instant mechanical behaviors of stenotic coronary artery and deployed stents have significant impacts on percutaneous coronary intervention prognosis. However, they could not be obtained directly from the current examination techniques, which are commonly used in clinical practice. Thus, we intend to investigate the instantaneous mechanical behaviors of deployed stent and artery through virtually stenting technology based on a real clinical case in assessment of geometric and biomechanical characteristics. Method: Finite element analysis models, including rigid guide catheter, six-folded balloon with conical tip, crimped and bended stent, stenotic coronary artery with soft plaques, were simulated through virtual mechanical expansion and recoil procedure. The morphology changes of coronary lumen, strain and stress distribution of involved components at different stages and apposition of stent struts were analyzed. Results: Lumen in the stenotic region restored patency obviously at maximum expansion and had an elastic recoil about 13.5% later. The maximum principal stress distribution of artery walls and plaque was mainly concentrated in the stenotic segment with the peak value of 1.252MPa and 2.975MPa at max expansion, 0.713MPa and 1.25MPa after recoil, respectively. The higher von Mises stress and plastic equivalent strain of stent were present at the bended strut and inter-ring connectors with the peak value of 714.2MPa and 0.2385 at max expansion, 694MPa and 0.2276 after recoil. Slight malappositions were found in the proximal segment and struts distribution in the stenotic sites showed certain asymmetry. Conclusion: The instant mechanical behaviors of artery and stent could be evaluated through virtual stenting approach in assessment of geometric and biomechanical characteristics. This may contribute to choosing the best stenting schemes and predicting the clinical outcomes for a specific patient.

In large blood vessels, migration of red blood cells (RBCs) affects the concentration of platelets and the transport of oxygen to the arterial endothelial cells. In this work, we investigate the locations where hydrodynamic diffusion of RBCs occurs and the effects of stenosis severity on shear-induced diffusion (SID) of RBCs, concentration distribution and wall shear stress (WSS). For the first time, multiphase mixture theory approach with Phillips shear-induced diffusive flux model coupled with Quemada non-Newtonian viscosity model has been applied to numerically simulate the RBCs macroscopic behavior in four different degrees of stenosis (DOS) geometries, viz., 30%, 50%, 70% and 85%. Considering SID of RBCs, the calculated average WSS increased by 77.70% which emphasises the importance of SID in predicting hemodynamic parameters. At the stenosis throat, it was observed that 85% DOS model had the lowest concentration of RBCs near the wall and highest concentration at the center. For the stenosis models with 70% and 85% DOS, the RBC lumen wall concentration at the distal section of stenosis becomes inhomogeneous with the maximum fluctuation of 1.568%. Finally, the wall regions with low WSS and low RBC concentrations correlate well with the atherosclerosis sites observed clinically.

This paper focuses on the dual quality of blood, Newtonian and non-Newtonian, in particular by exploring the energy curves. Careful investigation of the dual property of blood has been made by considering two different geometries to represent a stenosed arterial segment. We present a cautious assessment of non-Newtonian blood rheology impacts in arterial stream simulations by coupling the Newtonian and non-Newtonian models. The flow of energy through the two flow dimensions is meticulously investigated using velocity (kinetic energy), pressure, and wall shear stress (pressure energy). Besides, the proper implementation of an interface boundary condition (IBC) was emphasized to ensure consistency with the flow conditions downstream of a backward-facing step. The integration of the Newtonian and non-Newtonian models adjoins the novelty of the current research. The energy curves are obtained by implementing five different non-Newtonian models to designate a suitable non-Newtonian model for blood flow investigations. The combination of the non-Newtonian models enforced in this research is novel and particular attention is paid to the energy curves obtained. The conclusion was to elect the Carreau model as a suitable non-Newtonian rheological model for the blood flow study. This study was able to finalize the fact that the coupling of Newtonian and non-Newtonian models is necessary to obtain accurate results. For the sinusoidal waveform considered for the velocity, Carreau and the Power law models yield better results, eliminating the other non-Newtonian models from the list. With a better inlet condition imposed in the form of the Fourier series for pressure and velocity, the Carreau model yields the best results.

A method which can personalize the lumped parameter model of coronary artery and cardiovascular system based on the non-invasive physiological parameters has been developed. The parameters of system were determined by different physiological parameters. The heart module was determined by aortic pressure and heart rate; the systemic circulation module was determined by cardiac output, height and cardio-ankle vascular index (CAVI), while the CAVI was determined by age and aortic pressure; the coronary module was determined by the target waveforms of coronary flow rate predicted from cardiac output. The considerable results proved that this method could be applied to each patient.

Instantaneous wave-free ratio (iFR), an invasive index of coronary artery tree, can evaluate the functional performance of vascular stenosis without pharmacological vasodilators. The noninvasive assessment of diameter stenosis (DS) obtained from coronary computed tomography angiography (CTA) has high false positive rate in contrast to iFR. The aim of this study was to develop a numerical simulation method that predicts the iFR and noninvasively assess the myocardial ischemia. Based on the CTA images, a patient-specific three-dimensional model of the aorta and coronary arteries were reconstructed. A stenosis was created in the left anterior descending artery (LAD) by reducing the DS of geometric model (40%, 50%, 60%, 75% and 90%). The patient-specific LPM boundary condition were set up to compute iFRct value during the wave-free period at the resting condition. The computed pressure and flow of coronary artery were realistic as compared to literature data. In contrast to invasive iFR, the iFRct can make a cost-benefit balance in terms of clinical cost and patient’s health.

In this study, various models with different curvatures of bend and different inter-stenotic distances are created. The computations are carried out and the numerical results are compared with the computer simulation in a right coronary artery model reconstructed using the basic information from a coronary artery segment of a patient. Our results show that the curvature of bend significantly affects the wall shear stress (WSS) and the pressure drop (PD) in curved artery with two moderate stenoses. The location of the distal stenosis strongly influences the flow pattern downstream, while the effect of the location of the proximal stenosis is insignificant.

As a high-resolution optical imaging technology, Optical Coherence Tomography (OCT) has been widely used in the diagnosis and treatment of cardiovascular diseases. It has played an important role in the detection and identification of atherosclerotic plaques and has significant advantages. In this paper, we realized to extract the optical characteristic parameters of the target sample based on the OCT data by establishing optical transmission models conforming to the OCT principle. The optical phantoms and coronary artery of domestic pig were used as research samples to study the difference between the optical properties of the cardiovascular tissues. It can provide a basic method for further study of optical characteristic parameters of atherosclerotic plaques, and also lay a foundation for realizing the quantitative evaluation of atherosclerotic plaques with multiple optical characteristic parameters in the future.

An efficient and robust method for identification of coronary arteries and evaluation of the severity of the stenosis on the routine X-ray angiograms is proposed. It is a challenging process to accurately identify coronary artery due to poor signal-to-noise ratio, vessel overlap, and superimposition with various anatomical structures such as ribs, spine, or heart chambers. The proposed method consists of two major stages: (a) signal-based image segmentation and (b) vessel feature extraction. The 3D Fourier and 3D Wavelet transforms are first employed to reduce the background and noisy structures in the images. Afterwards, a set of matched filters was applied to enhance the coronary arteries in the images. At the end, clustering analysis, histogram technique, and size filtering were utilized to obtain a binary image that consists of the final segmented coronary arterial tree. To extract vessel features in terms of vessel centerline and diameter, a gradient vector-flow based snake algorithm is applied to determine the medial axis of a vessel followed by the calculations of vessel boundaries and width associated with the detected medial axis.

Atherosclerosis is a disease in which plaque builds up inside arteries. It is also considered as one of the most serious and common forms of cardiovascular disease which can lead to heart attack and stroke. In the current research, finite element method is used to anticipate plaque vulnerability based on peak plaque stress using human samples. A total of 23 healthy and atherosclerotic human coronary arteries, including 14 healthy and 9 atherosclerotic are removed within 5 h postmortem. The samples are mounted on a uniaxial tensile test machine and the obtained mechanical properties are used in finite element models. The results, including the Mooney–Rivlin hyperelastic constants of the samples as well as peak plaque stresses, are computed. It is demonstrated that the atherosclerotic human coronary arteries have significantly (p < 0.05) higher stiffness compared to healthy ones. The hypocellular plaque, in addition, has the highest stress values compared to the cellular and calcified ones and, consequently, is so prone to rupture. The calcified plaque type, nevertheless, has the lowest stress values and, remains stable. The results of this study can be used in the plaque vulnerability prediction and could have clinical implications for interventions and surgeries, such as balloon angioplasty, bypass and stenting.

Arterial thrombosis and atherosclerosis result in chronic total or partial occlusion of the coronary artery. Coronary artery disease (CAD) destroys some parts of the heart muscle tissue and is the leading cause of human deaths in the industrialized world. In this study, cardiovascular system is simulated by 42 compartments and then a coronary set (including artery, venous, myocardium and capillaries) is added to the model. Each vessel is modeled by three parameters, such as resistor, capacitor and inductor. These three parameters are variable with respect to the radius of the vessel. In this paper, first of all, aortic and coronary flow under healthy condition is studied. The obtained results are in complete agreement with experimental outcomes. Then cardiovascular system behavior in coronary artery stenosis condition is investigated. Finally, the effect of intra-coronary balloon pump on heart attack risk and also on stabilization of patient's emergency condition by mathematical simulation is analyzed. The results of modeling show that the balloon pumping of coronary artery is an advantageous way in rendering primary cure to patients. The proposed model, in addition, has implications for investigation of effects of different diseases on the cardiovascular system. It also has the potential to model different treatment methods on heart's performance and, as a result, recommend new methods in order to cure variant cardiovascular diseases.