Integrative model of coronary flow in anatomically based vasculature under myogenic, shear, and metabolic regulation

Namani, Ravi; Kassab, Ghassan S.; Lanir, Yoram

doi:10.1085/jgp.201711795

Cited by 23 publications

(46 citation statements)

References 104 publications

(183 reference statements)

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“…The four model parameters are: (1) the maximum decrease in vessel radius (or the peak amplitude), ρ m ; (2) ϕ m is the transvascular pressure at which the vessel radius decreases by ρ m (the pressure at peak amplitude); (3) the pressure bandwidth of the vessel radius change is C m (Namani et al, 2018 ); (4) and the exponent, m , is assumed to be 2.0 (Young et al, 2012 ).…”

Section: Collecting and Analyzing Existing Datamentioning

confidence: 99%

“…The model of Cornelissen and colleagues incorporated a network of vessels with diameter-dependent myogenic responses and generated theoretical pressure-flow curves with prominent autoregulation (Cornelissen et al, 2000 , 2002 ). Most recently, Namani et al provided an integrative model of coronary flow based on a realistic anatomy, active and passive flow determinants, and myogenic reactivity data (Namani et al, 2018 ). While important mechanistic insights were provided by these studies, a limitation of the previous modeling efforts is that they relied upon data from dissimilar species and/or ex vivo active autoregulation data (i.e., isolated hearts in which coronary flow typically exceeds values seen in vivo ).…”

Section: Introductionmentioning

confidence: 99%

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Role of Coronary Myogenic Response in Pressure-Flow Autoregulation in Swine: A Meta-Analysis With Coronary Flow Modeling

et al. 2018

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Myogenic responses (pressure-dependent contractions) of coronary arterioles play a role in autoregulation (relatively constant flow vs. pressure). Publications on myogenic reactivity in swine coronaries vary in caliber, analysis, and degree of responsiveness. Further, data on myogenic responses and autoregulation in swine have not been completely compiled, compared, and modeled. Thus, it has been difficult to understand these physiological phenomena. Our purpose was to: (a) analyze myogenic data with standard criteria; (b) assign results to diameter categories defined by morphometry; and (c) use our novel multiscale flow model to determine the extent to which ex vivo myogenic reactivity can explain autoregulation in vivo. When myogenic responses from the literature are an input for our model, the predicted coronary autoregulation approaches in vivo observations. More complete and appropriate data are now available to investigate the regulation of coronary blood flow in swine, a highly relevant model for human physiology and disease.

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Section: Collecting and Analyzing Existing Datamentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Role of Coronary Myogenic Response in Pressure-Flow Autoregulation in Swine: A Meta-Analysis With Coronary Flow Modeling

et al. 2018

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“…The inclusion of autoregulation may affect results presented in this study (Meier et al, 2004 ). It will also permit testing of further factors that affect local and global flow, as shown recently by Namani et al ( 2018 ).…”

Section: Limitationsmentioning

confidence: 88%

Computational Assessment of Blood Flow Heterogeneity in Peritoneal Dialysis Patients' Cardiac Ventricles

et al. 2018

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Dialysis prolongs life but augments cardiovascular mortality. Imaging data suggests that dialysis increases myocardial blood flow (BF) heterogeneity, but its causes remain poorly understood. A biophysical model of human coronary vasculature was used to explain the imaging observations, and highlight causes of coronary BF heterogeneity. Post-dialysis CT images from patients under control, pharmacological stress (adenosine), therapy (cooled dialysate), and adenosine and cooled dialysate conditions were obtained. The data presented disparate phenotypes. To dissect vascular mechanisms, a 3D human vasculature model based on known experimental coronary morphometry and a space filling algorithm was implemented. Steady state simulations were performed to investigate the effects of altered aortic pressure and blood vessel diameters on myocardial BF heterogeneity. Imaging showed that stress and therapy potentially increased mean and total BF, while reducing heterogeneity. BF histograms of one patient showed multi-modality. Using the model, it was found that total coronary BF increased as coronary perfusion pressure was increased. BF heterogeneity was differentially affected by large or small vessel blocking. BF heterogeneity was found to be inversely related to small blood vessel diameters. Simulation of large artery stenosis indicates that BF became heterogeneous (increase relative dispersion) and gave multi-modal histograms. The total transmural BF as well as transmural BF heterogeneity reduced due to large artery stenosis, generating large patches of very low BF regions downstream. Blocking of arteries at various orders showed that blocking larger arteries results in multi-modal BF histograms and large patches of low BF, whereas smaller artery blocking results in augmented relative dispersion and fractal dimension. Transmural heterogeneity was also affected. Finally, the effects of augmented aortic pressure in the presence of blood vessel blocking shows differential effects on BF heterogeneity as well as transmural BF. Improved aortic blood pressure may improve total BF. Stress and therapy may be effective if they dilate small vessels. A potential cause for the observed complex BF distributions (multi-modal BF histograms) may indicate existing large vessel stenosis. The intuitive BF heterogeneity methods used can be readily used in clinical studies. Further development of the model and methods will permit personalized assessment of patient BF status.

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“…A shortcoming in that work was the limitation to topology, ignoring the 3D distribution over the myocardium. More extensive work came from the group of Kassab, who in a series of studies described these characteristics in the arterial, capillary, and venous coronary bed of pigs, also based on corrosion casts, followed by extensive modeling and hemodynamic analyses (Kassab et al, 1993(Kassab et al, , 1999Kassab and Fung, 1994;Kalsho and Kassab, 2004;Kassab, 2005;Mittal et al, 2005a,b;Kaimovitz et al, 2008;Namani et al, 2018). Following initial work on manual segmentation of the coronary vasculature based on corrosion casts, our lab has developed an imaging cryomicrotome that allows for extensive 3D recording of branching structures (Spaan et al, 2005) and applied this technique for the study of network characteristics in several species and organs (van Horssen et al, 2010(van Horssen et al, , 2014van den Wijngaard et al, 2011;Hakimzadeh et al, 2014;Bedussi et al, 2015;Schwarz et al, 2017), culminating in the current work on the human heart.…”

Section: Previous Datamentioning

confidence: 99%

“…In the beating heart, systolic flow in notably the subendocardium is impaired by the contracting surrounding myocardium (Hoffman and Spaan, 1990). In a model study, Namani et al showed that not only is flow higher under passive conditions than under autoregulation, but that ignoring the interaction between vessels and the surrounding myocardium indeed results in increased flow and thus perfusion estimates (Namani et al, 2018). Bache et al found an increase in the subendocardium/subepicardium perfusion ratio with decreasing heart rate at maximal vasodilation (Bache and Cobb, 1977).…”

Section: Hemodynamic Predictionsmentioning

confidence: 99%

Topologic and Hemodynamic Characteristics of the Human Coronary Arterial Circulation

et al. 2020

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Background: Many processes contributing to the functional and structural regulation of the coronary circulation have been identified. A proper understanding of the complex interplay of these processes requires a quantitative systems approach that includes the complexity of the coronary network. The purpose of this study was to provide a detailed quantification of the branching characteristics and local hemodynamics of the human coronary circulation. Methods: The coronary arteries of a human heart were filled post-mortem with fluorescent replica material. The frozen heart was alternately cut and block-face imaged using a high-resolution imaging cryomicrotome. From the resulting 3D reconstruction of the left coronary circulation, topological (node and loop characteristics), topographic (diameters and length of segments), and geometric (position) properties were analyzed, along with predictions of local hemodynamics (pressure and flow). Results: The reconstructed left coronary tree consisted of 202,184 segments with diameters ranging from 30 µm to 4 mm. Most segments were between 100 µm and 1 mm long. The median segment length was similar for diameters ranging between 75 and 200 µm. 91% of the nodes were bifurcations. These bifurcations were more symmetric and less variable in smaller vessels. Most of the pressure drop occurred in vessels between 200 µm and 1 mm in diameter. Downstream conductance variability affected neither local pressure nor median local flow and added limited extra variation of local flow. The left coronary circulation perfused 358 cm 3 of myocardium. Median perfused volume at a truncation level of 100 to 200 µm was 20 mm 3 with a median perfusion of 5.6 ml/min/g and a high local heterogeneity. Conclusion: This study provides the branching characteristics and hemodynamic analysis of the left coronary arterial circulation of a human heart. The resulting model can be deployed for further hemodynamic studies at the whole organ and local level.

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Integrative model of coronary flow in anatomically based vasculature under myogenic, shear, and metabolic regulation

Cited by 23 publications

References 104 publications

Role of Coronary Myogenic Response in Pressure-Flow Autoregulation in Swine: A Meta-Analysis With Coronary Flow Modeling

Role of Coronary Myogenic Response in Pressure-Flow Autoregulation in Swine: A Meta-Analysis With Coronary Flow Modeling

Computational Assessment of Blood Flow Heterogeneity in Peritoneal Dialysis Patients' Cardiac Ventricles

Topologic and Hemodynamic Characteristics of the Human Coronary Arterial Circulation

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