Correlation of Computational Instantaneous Wave-Free Ratio with Fractional Flow Reserve for Intermediate Multi-Vessel Coronary Disease

2021 ◽  
Author(s):  
Arash Ghorbanniahassankiadeh ◽  
David S. Marks ◽  
John LaDisa
Keyword(s):  
Fractional Flow Reserve ◽  
Stokes Equations ◽  
Navier Stokes ◽  
Lesion Group ◽  
Patient Specific ◽  
Dynamics Modeling ◽  
Multiple Lesion ◽  
Fractional Flow ◽  
Navier Stokes Equations ◽  
Flow Reserve

Abstract This study computationally assesses the accuracy of an instantaneous wave-free ratio (iFR) threshold range compared to standard modalities such as fractional flow reserve (FFR) and coronary flow reserve (CFR) for multiple intermediate lesions near the left main (LM) coronary bifurcation. iFR is an adenosine-independent index encouraged for assessment of coronary artery disease, but different thresholds are debated. This becomes particularly challenging in multi-vessel disease when sensitivity to downstream lesions is unclear. Idealized LM coronary arteries with 34 different intermediate stenoses were created and categorized (Medina) as single and multiple lesion groups. Computational fluid dynamics modeling was performed with physiologic boundary conditions using an open source software (SimVascular; simtk.org) to solve the time-dependent Navier-Stokes equations. A strong linear relationship between iFR and FFR was observed among studied models, indicating computational iFR values of 0.92 and 0.93 are statistically equivalent to an FFR of 0.80 in single and multiple lesion groups, respectively. At the clinical FFR value (i.e. 0.8), a triple-lesion group had smaller CFR compared to the single and double lesion groups (e.g. triple=3.077 vs. single=3.133 and double=3.132). In general, the effect of additional intermediate downstream lesions (minimum lumen area >3 mm2) was not statistically significant for iFR and CFR. A computational iFR of 0.92 best predicts an FFR 0.80 and may be recommended as threshold criteria for computational assessment of LM stenosis following additional validation using patient-specific models.

A novel patient-specific model to compute coronary fractional flow reserve

2014 ◽  
Vol 116 (1) ◽  
pp. 48-55 ◽  
Author(s):  
Soon-Sung Kwon ◽  
Eui-Chul Chung ◽  
Jin-Seo Park ◽  
Gook-Tae Kim ◽  
Jun-Woo Kim ◽  
...  
Keyword(s):  
Fractional Flow Reserve ◽  
Specific Model ◽  
Patient Specific ◽  
Fractional Flow ◽  
Flow Reserve

scholarly journals Effects of the Haemodynamic Stimulus on the Location of Carotid Plaques Based on a Patient-Specific Mechanobiological Plaque Atheroma Formation Model

2021 ◽  
Vol 9 ◽  
Author(s):  
Patricia Hernández-López ◽  
Myriam Cilla ◽  
Miguel Martínez ◽  
Estefanía Peña
Keyword(s):  
Carotid Arteries ◽  
Stokes Equations ◽  
Shape Index ◽  
Mechanical Stimulus ◽  
Diffusion Reaction ◽  
Navier Stokes ◽  
Patient Specific ◽  
Clinical Images ◽  
Navier Stokes Equations ◽  
Using Data

In this work, we propose a mechanobiological atheroma growth model modulated by a new haemodynamic stimulus. To test this model, we analyse the development of atheroma plaques in patient-specific bifurcations of carotid arteries for a total time of 30 years. In particular, eight geometries (left or right carotid arteries) were segmented from clinical images and compared with the solutions obtained computationally to validate the model. The influence of some haemodynamical stimuli on the location and size of plaques is also studied. Plaques predicted by the mechanobiological models using the time average wall shear stress (TAWSS), the oscillatory shear index (OSI) and a new index proposed in this work are compared. The new index predicts the shape index of the endothelial cells as a combination of TAWSS and OSI values and was fitted using data from the literature. The mechanobiological model represents an evolution of the one previously proposed by the authors. This model uses Navier-Stokes equations to simulate blood flow along the lumen in the transient mode. It also employs Darcy's law and Kedem-Katchalsky equations for plasma and substance flow across the endothelium using the three-pore model. The mass balances of all the substances that have been considered in the model are implemented by convection-diffusion-reaction equations, and finally the growth of the plaques has been computed. The results show that by using the new mechanical stimulus proposed in this study, prediction of plaques is, in most cases, better than only using TAWSS or OSI with a minimal and maximal errors on stenosis ratio of 2.77 and 32.89 %, respectively. However, there are a few geometries in which haemodynamics cannot predict the location of plaques, and other biological or genetic factors would be more relevant than haemodynamics. In particular, the model predicts correctly eleven of the fourteen plaques presented in all the geometries considered. Additionally, a healthy geometry has been computed to check that plaque is not developed with the model in this case.

A Particle-Based Model for Prediction of Cement Diffusion During Osteoporotic Hip Augmentation Surgery: Theory and Validation

2010 ◽  
Author(s):  
E. Basafa ◽  
Y. Otake ◽  
M. D. Kutzer ◽  
R. S. Armiger ◽  
M. Armand
Keyword(s):  
Bone Cement ◽  
Stokes Equations ◽  
Navier Stokes ◽  
Patient Specific ◽  
Osteoporotic Bone ◽  
Navier Stokes Equations ◽  
Injection Process ◽  
Particle Hydrodynamics ◽  
Smoothed Particle ◽  
And Control

Elderly patients with preexisting osteoporotic hip fracture are at high risk of a subsequent fracture in their contralateral hip. Current preventive approaches commonly have a long delay in restoring bone strength leaving patients at continued risk despite preventive efforts. Femoroplasty — injection of bone cement into the proximal femur — has been proposed as a potential preventive approach. However, it can cause complications because of extravasation of the cement into unwanted regions of the bone and an increased pressure within the bone, if not controlled and planned carefully. Therefore, precise modeling of the diffusion of the bone cement in osteoporotic bone and control over the injection process is of substantial importance. This paper presents a patient-specific fluid dynamics model to simulate the diffusion of the bone cement inside femur. The model is based on the smoothed particle hydrodynamics (SPH) method for particle-based modeling of fluids. The Navier-Stokes equations were built into the SPH formulations and viscosity effects were added to model the flow of cement inside porous media. To validate the model, a new prototype automatic injection device was used to inject acrylic silicone into a porous foam block. Results of simulation of the injection show close matching with experimental data. The model is therefore promising for further development of optimized and fully controlled femoroplasty procedures.

scholarly journals The role of extra-coronary vascular conditions that affect coronary fractional flow reserve estimation.

2021 ◽  
Author(s):  
Jermiah Joseph ◽  
Daniel Goldman ◽  
Sanjay R Kharche
Keyword(s):  
Atrial Fibrillation ◽  
Fractional Flow Reserve ◽  
Microvascular Disease ◽  
Patient Specific ◽  
Fractional Flow ◽  
Reserve Estimation ◽  
Coronary Vasculature ◽  
Flow Reserve ◽  
Flow Investigation ◽  
The Right

The treatment of coronary stenosis is often based upon invasive high risk surgical assessment. The surgical assessment quantifies the fractional flow reserve (FFR), a ratio of distal to proximal pressures in respect of the stenosis. Non-invasive imaging-computational methodologies call for robust and calibrated mathematical descriptions of the coronary vasculature that can be personalized. In addition, it is important to understand non-vascular factors that FFR. In this preliminary work, a 0D coronary vasculature model capable of personalization was implemented. The model was used to demonstrate the roles of focal and extended stenosis (intra-vascular), as well as microvascular disease and atrial fibrillation (extra-vascular) on FFR. It was found that FFR the right coronary artery is maximally affected by disease conditions. Interestingly, the severity of both microvascular disease and atrial fibrillation were found to be secondary to their mere presence regarding the modelling based FFR estimation. The 0D model provides a computationally inexpensive instrument for in silico coronary blood flow investigation as well as clinical-imaging decision making. Further- more, it establishes a basis for 3D computational fluid dynamics assessment of FFR in patient specific geometries.

Assessment of Invasive Fractional Flow Reserve Procedures Using Computational Fluid Dynamics

2020 ◽  
Author(s):  
Yasser Abuouf ◽  
Muhamed Albadawi ◽  
Shinichi Ookawara ◽  
Mahmoud Ahmed
Keyword(s):  
Blood Flow ◽  
Coronary Artery ◽  
Pressure Drop ◽  
Fractional Flow Reserve ◽  
Treatment Plan ◽  
Three Dimensional ◽  
Patient Specific ◽  
Concomitant Treatment ◽  
Fractional Flow ◽  
Flow Reserve

Abstract Coronary artery disease is the abnormal contraction of heart supply blood vessel. It may lead to major consequences such as heart attack and death. This narrowing in the coronary artery limits the oxygenated blood flow to the heart. Thus, diagnosing its severity helps physicians to select the appropriate treatment plan. Fractional Flow Reserve (FFR) is one of the most accurate methods to pinpoint the stenosis severity. The advantages of FFR are high accuracy, immediate estimation of the severity of the stenosis, and concomitant treatment using balloon or stent. Nevertheless, the main disadvantage of the FFR is being an invasive procedure that requires an incision under anesthesia. Moreover, inserting the guidewire across the stenosis may result in a ‘tight-fit’ between the vessel lumen and the guidewire. This may cause an increase in the measured pressure drop, leading to a false estimation of the blood flow parameters. To estimate the errors in diagnosis procedures, a comprehensive three-dimensional model blood flow along with guidewire is developed. Reconstructed three-dimensional coronary artery geometry from a patient-specific scan is used. Blood is considered non-Newtonian and the flow is pulsatile. The comprehensive model is numerically simulated using boundary conditions. Based on the predicted results, the ratio between pressure drop and distal dynamic pressure (CDP) is studied. The predicted results for each case are compared with the control case (the case without guidewire) and analyzed. It was found that simulating the model by placing the guidewire at a full position prior to the simulation leads to an overestimation of the CDP as it increases by 34.3%. However, simulating the procedure of guidewire insertion is more accurate. It shows that the CDP value increases by 7%.

An Outflow Boundary Condition Model for Noninvasive Prediction of Fractional Flow Reserve in Diseased Coronary Arteries

2018 ◽  
Vol 140 (4) ◽  
Author(s):  
Iyad A. Fayssal ◽  
Fadl Moukalled ◽  
Samir Alam ◽  
Hussain Isma'eel
Keyword(s):  
Boundary Condition ◽  
Coronary Arteries ◽  
Fractional Flow Reserve ◽  
Physiological Parameters ◽  
Arterial System ◽  
Patient Specific ◽  
Fractional Flow ◽  
Condition Model ◽  
Flow Reserve ◽  
Boundary Condition Model

This paper reports on a new boundary condition formulation to model the total coronary myocardial flow and resistance characteristics of the myocardial vascular bed for any specific patient when considered for noninvasive diagnosis of ischemia. The developed boundary condition model gives an implicit representation of the downstream truncated coronary bed. Further, it is based on incorporating patient-specific physiological parameters that can be noninvasively extracted to account for blood flow demand to the myocardium at rest and hyperemic conditions. The model is coupled to a steady three-dimensional (3D) collocated pressure-based finite volume flow solver and used to characterize the “functional significance” of a patient diseased coronary artery segment without the need for predicting the hemodynamics of the entire arterial system. Predictions generated with this boundary condition provide a deep understanding of the inherent challenges behind noninvasive image-based diagnostic techniques when applied to human diseased coronary arteries. The overall numerical method and formulated boundary condition model are validated via two computational-based procedures and benchmarked with available measured data. The newly developed boundary condition is used via a designed computational methodology to (a) confirm the need for incorporating patient-specific physiological parameters when modeling the downstream coronary resistance, (b) explain the discrepancies presented in the literature between measured and computed fractional flow reserve (FFRCT), and (c) discuss the current limitations and future challenges in shifting to noninvasive assessment of ischemia.

scholarly journals Quantification of effects of mean blood pressure and left ventricular mass on noninvasive fast fractional flow reserve

2020 ◽  
Vol 319 (2) ◽  
pp. H360-H369
Author(s):  
Jun-Mei Zhang ◽  
Gaurav Chandola ◽  
Ru-San Tan ◽  
Ping Chai ◽  
Lynette L. S. Teo ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Left Ventricular Mass ◽  
Fractional Flow Reserve ◽  
Disease Diagnosis ◽  
Left Ventricular ◽  
Mean Blood Pressure ◽  
Patient Specific ◽  
Fractional Flow ◽  
Flow Reserve ◽  
Ventricular Mass

While brachial mean blood pressure (MBP) and left ventricular mass (LVM) measured from CTCA are the two CFD simulation input parameters, their effects on noninvasive fractional flow reserve (FFRB) have not been systematically investigated. We demonstrate that inaccurate MBP and LVM inputs differing from patient-specific values could result in misclassification of borderline ischemic lesions. This is important in the clinical application of noninvasive FFR in coronary artery disease diagnosis.

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