scholarly journals IMPROVED NUMERICAL MODEL OF THE ARTERIAL WALL APPLIED FOR SIMULATIONS OF STENT DEPLOYMENT WITHIN PATIENT-SPECIFIC CORONARY ARTERIES

2020 ◽  
pp. 1-5
Author(s):  
Tijana Djukic ◽  
Igor Saveljic ◽  
Gualtiero Pelosi ◽  
Oberdan Parodi ◽  
Nenad Filipovic
Keyword(s):  
Blood Flow ◽  
Numerical Model ◽  
Coronary Arteries ◽  
Arterial Wall ◽  
Arterial Stenosis ◽  
Patient Specific ◽  
Stent Deployment ◽  
Normal Blood Flow ◽  
Experimental Values ◽  
Treatment Procedures

Arterial stenosis is the obstruction of normal blood flow that is caused by atherosclerosis. One of the endovascular treatment procedures in this case is the implantation of a stent to restore the blood flow. This study presented an improved numerical model that can precisely simulate the deformation of human arterial wall in coronary arteries, during the stent deployment process. The new model considered the arterial wall as an incompressible, isotropic and hyperelastic material. The material coefficients were defined according to experimental values presented in literature. The accuracy of the numerical model was investigated by comparing the results with follow up data obtained in clinical examination. The small relative and standard deviation error prove that this numerical model can be used to assist clinicians in decision making and treatment planning with reliable predictions of the outcome of the stent deployment procedure.

scholarly journals COMPUTER MODELING OF STENT DEPLOYMENT AND PLAQUE PROGRESSION IN THE CORONARY ARTERIES

2018 ◽  
Vol 9 (1) ◽  
Author(s):  
Nenad Filipović ◽  
Velibor Isailović ◽  
Žarko Milosević ◽  
Dalibor Nikolić ◽  
Igor Saveljić ◽  
...  
Keyword(s):  
Blood Flow ◽  
Coronary Arteries ◽  
Mixed Finite Element ◽  
Flow Simulation ◽  
Reaction Diffusion ◽  
Navier Stokes ◽  
Stent Deployment ◽  
Specific Patient ◽  
Nonlinear Viscoelastic ◽  
Solute Dynamics

In this study stent deployment modeling with plaque formation and pro- gression for specific patient in the coronary arteries are described. State of the art method for the reported investigations of blood flow in the stented arteries is described. In the met- hod section, image segmentation method for arteries with stent is shortly described. Blood flow simulation is described with Navier-Stokes and continuity equation. Blood vessel tis- sue is modeled with nonlinear viscoelastic material properties. The coupling of fluid dynamics and solute dynamics at the endothelium was achieved by the Kedem-Katchalsky equations. The inflammatory process is modeled using three additional reaction-diffusion partial differential equations. Coupled method with mixed finite element and DPD (Dissi- pative Particle Dynamics) method is presented. In the results section, the examples with rigid and deformable arterial wall with stented and unstented arteries are presented. Effecti- ve stress analysis results for stent deployment have been shown. It can be seen that stent reduces wall shear stress significantly after deployment which is caused by opening the artery and reducing the narrowing. Some results for stent deployment model obtained with solver developed under PAK software package. These computer models can make better understanding and preparation of the surgeons for stent deployment in everyday clinical practice.

Abstract 566: Experimental Investigation of Blood Flow in the Femoral Bifurcated Artery

2015 ◽  
Vol 35 (suppl_1) ◽  
Author(s):  
Azadeh Lotfi ◽  
Zachary Lawler ◽  
Omar Jan ◽  
Tracie Barber ◽  
Anne Simmons
Keyword(s):  
Blood Flow ◽  
Additional Treatment ◽  
Arterial Stenosis ◽  
Patient Specific ◽  
Local Flow ◽  
Micro Piv ◽  
Stent Restenosis ◽  
Tibial Arteries ◽  
Hemodynamic Disturbance ◽  
Good Patency

Stent implantation is one of the most widely used interventional treatments for arterial stenosis which occurs predominantly due to atherosclerosis. Although stent placement can ensure very good patency of the lumen, stent-induced hemodynamic disturbance, which can lead to further stenosis, still remains a common clinical complication. This study investigates the degree of hemodynamic disturbance induced by stenting an idealized bifurcated popliteal artery, which branches into the anterior and posterior tibial arteries, and is known as a site prone to atherosclerosis. Both stent-free and stented bifurcated arteries were examined, and the local flow patterns analysed for the comparative disturbance through the use of Micro Particle Image Velocity (micro-PIV) system. A life-size model of the artery was reconstructed using dimensions obtained from a patient specific MRI scan. The experiments were conducted under steady flow conditions, and the flow rates across the bifurcation were visualized and measured using the micro-PIV system. It was shown that hemodynamic disturbances induced by the blood flow over the stent can further disrupt the arterial wall downstream of the stent causing further downstream vascular damage in addition to the in-stent restenosis. This downstream vascular disruption may require additional treatment depending on the type and severity of the damage. The results also support the hypothesis that links certain flow dynamic behaviour with the development of early intimal thickening, as the near wall low fluid momentum regions are found at locations where thickening was localized in bifurcated arteries in clinical studies.

DIPYRIDAMOLE ALONE OR WITH LOW DOSE ASPIRIN DOES NOT PREVENT ACUTE PLATELET THROMBUS FORMATION IN STENOSED DOG CORONARY ARTERIES

1987 ◽  
Author(s):  
J D Folts ◽  
S R Smith
Keyword(s):  
Clinical Trials ◽  
Blood Flow ◽  
Coronary Arteries ◽  
Low Dose ◽  
Thrombus Formation ◽  
Arterial Stenosis ◽  
In Vivo Model ◽  
Acute Ischemia ◽  
Pig Coronary Arteries

Dipyridamole (Dip) is reputed to inhibit (I) platelet aggregation (PA) and acute thrombus formation (ATF) by two mechanisms including inhibiting 1.) platelet (Pt) phosphodiesterase, 2.) adenosine (A) reuptake by red cells, which should raise plasma A. Both effects should raise Pt cyclic AMP and thus be a potent platelet inhibitor (PI). Because aspirin (AS) inhibits Pt thromboxane A2 production, a synergistic (S) PI effect for ASA and Dip given together has been postulated and used in clinical trials but this S has never been shown to I ATP in any in vivo model, which reasonably mimics human arterial stenosis. We have shown that ATF followed by embolization, occurs periodically in mechanically stenosed (MS) monkey and rabbit carotid arteries, and dog (D) and pig coronary arteries (CA), causing cyclical reductions in coronary blood flow (CRF) (measured with EMF probes) and periodic acute ischemia, and that these CRF can be abolished with a variety of PI including 3.0 mg/kg of ASA. To determine if there is a S effect between ASA and Dip, in open chest D, Dip was given, 2.0 mg/kg IV to D with a MS circumflex CA and having 14±5 CRF’s per hour, due to periodic ATF; and simultaneously flow measured in an unstenosed normal LAD CA. The frequency and size of CRF’s were not changed by Dip, although ABP decreased 21±9 mm Hg and blood flow in the unstenosed LAD increased 259±47%. A low dose of ASA, 1.0 mg/kg, which by itself diminishes but does not abolish CRF’s in this model was given IV 10 min. after Dip and CRF’s continued unchanged. When a second dose of ASA 1.0 mg/kg was given IV to reach the minimum effective dose of ASA in this model, CRF were abolished in all D. Thus Dip was not effective alone or in combination with low dose ASA to I CRF in this model which simulates the patient with stenosed CA. The majority of clinical trials that show inhibition of ATF, used ASA and Dip together without 3 separate patient groups on Dip alone, ASA alone and ASA plus Dip. The widespread use of Dip with ASA to prevent ATF in man needs to be reevaluated.

scholarly journals Integrating Patient-Specific Electrocardiogram Signals and Image-Based Computational Fluid Dynamics Method to Analyze Coronary Blood Flow in Patients during Cardiac Arrhythmias

2019 ◽  
Vol 40 (2) ◽  
pp. 264-272
Author(s):  
Szu-Hsien Chou ◽  
Kuan-Yu Lin ◽  
Zhen-Ye Chen ◽  
Chun-Jung Juan ◽  
Chien-Yi Ho ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Blood Flow ◽  
Coronary Artery ◽  
Cardiac Arrhythmia ◽  
Coronary Arteries ◽  
Flow Rate ◽  
Blood Flow Rate ◽  
Patient Specific ◽  
Ecg Signals

Abstract Purpose The aim of this study was to use the computational fluid dynamics (CFD) method, patient-specific electrocardiogram (ECG) signals, and computed tomography three-dimensional image reconstruction technique to investigate the blood flow in coronary arteries during cardiac arrhythmia. Methods Two patients with premature ventricular contraction-type cardiac arrhythmia and one with atrial fibrillation-type cardiac arrhythmia were investigated. The inlet velocity of the coronary artery in simulation was applied with the measured velocity profile of the left ventricular outflow tract (LVOT) from the Doppler echocardiography. The measured patient central aortic blood pressure waveform was employed for the coronary artery outlet in simulation. The no-slip boundary condition was applied to the arterial wall. Results For the patient with irregular cardiac rhythms (Case I), the coronary blood flow rate under the shortened and lengthened cardiac rhythms were 0.66 and 0.96 mL/s, respectively. In Case II, the maximum velocity at the LVOT under a normal heartbeat was found to be 101 cm/s, whereas the average value was 73 cm/s. In Case III, the patient was also diagnosed with a congenital stenosis problem at the myocardial bridge (MCB) at the LAD. The measured blood flow rate at the MCB of the LAD for the three heartbeats in Case III was found to be 0.68, 1.08, and 1.14 mL/s. Conclusion The integration of patient-specific ECG signals and image-based CFD methods can clearly analyze hemodynamic information for patients during cardiac arrhythmia. The cardiac arrhythmia can reduce the blood flow in the coronary arteries.

scholarly journals EXPERIMENTAL TESTING AND NUMERICAL MODELLING OF STENTS IN THE CORONARY ARTERIES

2016 ◽  
Vol 7 (2) ◽  
Author(s):  
Nenad Filipović ◽  
Dalibor Nikolić ◽  
Igor Saveljić ◽  
Themis Exarchos ◽  
Oberdan Parodi
Keyword(s):  
Numerical Methods ◽  
Coronary Arteries ◽  
Arterial Wall ◽  
Experimental Testing ◽  
Flow Simulation ◽  
Reaction Diffusion ◽  
Navier Stokes ◽  
Stent Deployment ◽  
Specific Patient ◽  
Solute Dynamics

In this study, experimental and numerical stent modelling with plaque formation and progression for specific patient in the coronary arteries is described. In the method, section experimental stent testing is firstly described. Then numerical methods with finite element methods are given. Blood flow simulation is described with Navier-Stokes and continuity equation. Blood vessel wall is modelled with nonlinear viscoelastic material properties. The coupling of fluid dynamics and solute dynamics at the endothelium was achieved by the Kedem-Katchalsky equations. The inflammatory process is modelled using three additional reaction-diffusion partial differential equations. In the results section, the examples with rigid and deformable arterial wall with stented and unstented arteries are presented. Effective stress analysis results for stent deployment have been shown. These experimental and numerical methods can give better understanding of stent deployment procedure and arterial wall response in everyday clinical practice.

scholarly journals 3D Reconstruction of Coronary Artery Stents From Optical Coherence Tomography: Experimental Validation and Clinical Feasibility

2021 ◽  
Author(s):  
Wei Wu ◽  
Khan Behram A. ◽  
Mohammadali Sharzehee ◽  
Shijia Zhao ◽  
Saurabhi Samant ◽  
...  
Keyword(s):  
Coronary Artery ◽  
3D Reconstruction ◽  
Coronary Arteries ◽  
Side Branch ◽  
Patient Specific ◽  
Micro Computed Tomography ◽  
Stent Deployment ◽  
Structural Morphology ◽  
Stent Strut ◽  
Coronary Artery Stents

Abstract The structural morphology of stents (e.g. expansion, lumen scaffolding, strut apposition, tissue protrusion, side branch jailing, strut fracture), and the local hemodynamic environment after stent deployment in coronary arteries are key determinants of procedural success and subsequent clinical outcomes. High-resolution intracoronary imaging has the potential to enable the geometrically correct 3D reconstruction of coronary stents. The aim of this work was to present a novel algorithm for 3D stent reconstruction of coronary artery stents by OCT and angiography, and test experimentally its accuracy, reproducibility, clinical feasibility and ability to perform CFD studies. Our method has the following steps: 3D lumen reconstruction by OCT and angiography, stent strut segmentation on OCT images, packaging, rotation and straightening of the segmented struts, and planar unrolling of the segmented struts, planar stent wireframe reconstruction, rolling back of the planar stent wireframe to the 3D reconstructed lumen, and stent volume reconstruction. We tested the accuracy and reproducibility of our method in stented patient-specific silicone models using micro computed tomography and stereoscopy as reference. The clinical feasibility and CFD studies were performed in clinically stented coronary bifurcations. Our experimental and clinical studies showed that our proposed algorithm can reproduce the complex stent configuration in space with high precision and reproducibility. Furthermore, our studies showed that the algorithm is feasible in clinical cases with stents deployed in diseased, bifurcated coronary arteries, enabling CFD studies to assess the hemodynamic environment. Notably, the high accuracy of our algorithm was consistent across different stent designs and diameters. Our method coupled with patient-specific CFD studies can facilitate stenting optimization, training in stenting techniques, and stent research and development.

Remodeling of the arterial wall: Response to restoration of normal blood flow after flow reduction

Biorheology ◽  
2018 ◽  
Vol 54 (2-4) ◽  
pp. 95-108 ◽  
Author(s):  
Kozaburo Hayashi ◽  
Daichi Kakoi ◽  
Akihisa Makino
Keyword(s):  
Blood Flow ◽  
Arterial Wall ◽  
Normal Blood ◽  
Flow Reduction ◽  
Normal Blood Flow

scholarly journals Myocardial Perfusion Simulation for Coronary Artery Disease: A Coupled Patient-Specific Multiscale Model

2020 ◽  
Author(s):  
Lazaros Papamanolis ◽  
Hyun Jin Kim ◽  
Clara Jaquet ◽  
Matthew Sinclair ◽  
Michiel Schaap ◽  
...  
Keyword(s):  
Coronary Artery Disease ◽  
Blood Flow ◽  
Coronary Artery ◽  
Coronary Arteries ◽  
Obstructive Coronary Artery Disease ◽  
Flow Simulation ◽  
Multiscale Model ◽  
Patient Specific ◽  
Human Data ◽  
Artery Disease

AbstractPatient-specific models of blood flow are being used clinically to diagnose and plan treatment for coronary artery disease. A remaining challenge is bridging scales from flow in arteries to the micro-circulation supplying the myocardium. Previously proposed models are descriptive rather than predictive and have not been applied to human data. The goal here is to develop a multiscale patient-specific model enabling blood flow simulation from large coronary arteries to myocardial tissue. Patient vasculatures are segmented from coronary computed tomography angiography data and extended from the image-based model down to the arteriole level using a space-filling forest of synthetic trees. Blood flow is modeled by coupling a 1D model of the coronary arteries to a single-compartment Darcy myocardium model. Simulated results on five patients with non-obstructive coronary artery disease compare overall well to [$$^{15}$$ 15 O]$$\text {H}_{{2}}$$ H 2 O PET exam data for both resting and hyperemic conditions. Results on a patient with severe obstructive disease link coronary artery narrowing with impaired myocardial blood flow, demonstrating the model’s ability to predict myocardial regions with perfusion deficit. This is the first report of a computational model for simulating blood flow from the epicardial coronary arteries to the left ventricle myocardium applied to and validated on human data.

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