Microcalcifications Increase Coronary Vulnerable Plaque Rupture Potential: A Patient-Based Micro-CT Fluid–Structure Interaction Study

Abstract

Asymptomatic vulnerable plaques (VP) in coronary arteries accounts for significant level of morbidity. Their main risk is associated with their rupture which may prompt fatal heart attacks and strokes. The role of microcalcifications (micro-Ca), embedded in the VP fibrous cap, in the plaque rupture mechanics has been recently established. However, their diminutive size offers a major challenge for studying the VP rupture biomechanics on a patient specific basis. In this study, a highly detailed model was reconstructed from a post-mortem coronary specimen of a patient with observed VP, using high resolution micro-CT which captured the microcalcifications embedded in the fibrous cap. Fluid-structure interaction (FSI) simulations were conducted in the reconstructed model to examine the combined effects of micro-Ca, flow phase lag and plaque material properties on plaque burden and vulnerability. This dynamic fibrous cap stress mapping elucidates the contribution of micro-Ca and flow phase lag VP vulnerability independently. Micro-Ca embedded in the fibrous cap produced increased stresses predicted by previously published analytical model, and corroborated our previous studies. The 'micro-CT to FSI' methodology may offer better diagnostic tools for clinicians, while reducing morbidity and mortality rates for patients with vulnerable plaques and ameliorating the ensuing healthcare costs.

Plaque Rupture Relationship to Plaque Composition in Coronary Arteries. A 320-Slice CT Angiographic Analysis

“…The superior contrast resolution of this CT captured the micro calcifications embedded in the fibrous cap, which would otherwise be missed, by the routine CT scanners and IVUS. 16 Our findings that plaque rupture is strongly associated with mixed plaque morphology, where specks of calcification are embedded in a background soft matrix, correlate with the above studies (Figs. 7 and 8).…”

A mechanistic analysis of the role of microcalcifications in atherosclerotic plaque stability: potential implications for plaque rupture

“…This study, combined with previous 3D FEA and fluidstructure interaction models (4,34,43,47) and ex vivo animal models (17), indicates the necessity for including Calcs in any realistic calculation of the PCS. The cap thickness and lipid/necrotic core size are clearly not the only determinants of plaque vulnerability.…”

“…43, like the present study, used accurate Mimics 3D reconstruction and the FSI model in Ref. 34. The primary difference is that we have greatly refined the FEA meshes at the interface of the Calcs and have optimized the type and number of elements and submodels required to maintain reasonable computational effort.…”

Effects of longitudinal asymmetric distribution of a lipid core on plaque wall stress

“…The Navier-Stokes equation with arbitrary Lagrangian-Eulerian formulation was used to solve governing equations in the presence of fluid-structure interaction (FSI), and a transient implicit scheme was applied to fluid flow computations. The velocity waveform obtained from a coronary flow waveform and the physiological pressure waveform (Rambhia et al, 2012) were applied at the inlet and the outlet of the vessel, respectively, in order to consider the phase lag between the pressure and the flow waves (Fig. 3).…”