Theoretical models for coronary vascular biomechanics: Progress & challenges

Abstract

A key aim of the cardiac Physiome Project is to develop theoretical models to simulate the functional behaviour of the heart under physiological and pathophysiological conditions. Heart function is critically dependent on the delivery of an adequate blood supply to the myocardium via the coronary vasculature. Key to this critical function of the coronary vasculature is system dynamics that emerge via the interactions of the numerous constituent components at a range of spatial and temporal scales. Here, we focus on several components for which theoretical approaches can be applied, including vascular structure and mechanics, blood flow and mass transport, flow regulation, angiogenesis and vascular remodelling, and vascular cellular mechanics. For each component, we summarise the current state of the art in model development, and discuss areas requiring further research. We highlight the major challenges associated with integrating the component models to develop a computational tool that can ultimately be used to simulate the responses of the coronary vascular system to changing demands and to diseases and therapies.

Scalability and in vivo validation of a multiscale numerical model of the left coronary circulation

“…Validation of such models requires direct comparison of simulated and experimental waveform shapes, including any high-frequency flow transients. However, although this has been performed for systemic large arteries (53), very little validation of 1D/multiscale coronary arterial models has been presented, a void that has been recognized in recent reviews (34,73).Moreover, to our knowledge no models (multiscale or otherwise) of the newborn coronary circulation have been described or validated. Indeed, aside from a few published Doppler velocity recordings (47, 48), relatively little information about phasic coronary hemodynamics in the newborn is available.…”

Evolution and rupture of vulnerable plaques: a review of mechanical effects

“…The treatment of the flow boundary conditions for the carotid and aortic arch is quite similar, whereas circulation beds such as coronary vasculature have a specific hemodynamic condition and require a specific treatment. The complexity of the implementation of numerical methods in the coronary vasculature comes from the different spatial (arterial, venous, capillary system) and temporal scales (short, cardiac cycle changes; long, remodeling and neovascularization) involved 33 in the modeling, but also from the strong coupling between mechanical and biological effects. 34 Indeed, the specificity of the coronary circulation is the compression of the blood vessels as the heart contracts, combined with the necessity to provide continuous perfusion to match metabolic rates (such as oxygen).…”

“…34 Indeed, the specificity of the coronary circulation is the compression of the blood vessels as the heart contracts, combined with the necessity to provide continuous perfusion to match metabolic rates (such as oxygen). 33 During the systole, the contracting myocardium generates a high level of intramyocardial pressure that compresses the coronary microvasculature, thereby impeding blood flow. Conversely, during diastole (much longer than the systole), intraventricular pressures transmitted into the left ventricular wall exert a small compressive force on the intramural vasculature, creating "waterfalls" at the level of the arterioles and the venules.…”

“…These adjustments correspond mainly to a change in the diameter of the arterioles and microvessels. The extensive reviews of Waters et al, 33 Westerhof et al, 34 and Duncker and Bache 35 give a detailed insight of the complexity of the flow in coronary vasculature. In particular, Waters et al 33 recently reviewed current challenges to model accurately coronary vascular biomechanics.…”

euHeart: personalized and integrated cardiac care using patient-specific cardiovascular modelling

“…Pressure boundary conditions are applied to the endocardium along with no-flux flow conditions at the endo-and epicardial surfaces. Apart from its clinical use in diagnosis support, the resulting model provides potential to analyse a wider variety of biophysical processes relevant at different levels in the coronary circulation as recently reviewed [62,64]. In the past 2 years, the focus has been on improving technologies for obtaining and interpreting images [65,66].…”