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Session: Poster Session 1 (Even numbers)
Session starts: Thursday 26 January, 16:00
Presentation starts: 16:00

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Su Guvenir Torun (Erasmus Medical Center)
Pablo de Miguel Munoz (Erasmus Medical Center)
Hanneke Crielaard (Erasmus Medical Center)
Hence Verhagen (Erasmus Medical Center)
Gert-Jan Kremers (Erasmus Medical Center)
Antonius van der Steen (Erasmus Medical Center)
Ali C. Akyildiz (Erasmus Medical Center)

Abstract:
Biomechanical analysis of atherosclerotic plaque rupture is crucial since it is the local failure of fibrous plaque tissue. Currently, the knowledge on mechanical failure properties of fibrous plaque is scarce [1,2], and limited to global properties based on homogeneity assumption. However, the fibrous plaque has a highly collagenous heterogeneous structure, and its failure properties should be investigated locally, together with the underlying collagen structure information. Yet, only one study [1] investigated the structural and failure properties of carotid fibrous plaques, but it was limited to the global failure properties obtained at the ultimate failure. However, initiation of fibrous plaque rupture occurs before the ultimate failure. In this study, for the first time, we investigated local failure properties and the collagen structure of human carotid fibrous plaques at the rupture initiation. The pipeline consists of uniaxial tensile testing combined with digital image correlation, for obtaining local deformation at the failure, and second harmonic generation imaging, for the assessment of local collagen predominant angle (pDA) and dispersion of fibrous plaque strips (n=30). In structural analysis, the pre-testing collagen pDA in ~90% of measured local regions of all strips were observed to have close to circumferential orientation, with a varying level of local dispersion. Similarly, rupture regions were also observed to have close to circumferential pDAs. In mechanical analysis, the comparison of global strain measurements to local DIC measurements showed that the global analysis greatly underestimated tissue rupture strain. In addition, the locations of the high circumferential strain regions were correlated with the rupture regions. To the best of our knowledge, this study is the first to characterize local mechanical failure and structural collagen of fibrous plaques at rupture initiation. Findings from this work highlight the importance of patient-specific local assessment of mechanical failure and structural properties of the highly heterogenous fibrous plaques. The circumferential strain appears to be an important candidate for local rupture initiation assessment, whereas the structural collagen parameters alone were not observed to be sufficient. For future work, mechanical testing and structural imaging could be combined for the assessment of collagen re-alignment and local strains at rupture initiation. [1] Johnston R et al., Acta Biomaterialia, 124: 291-300, 2021. [2] Teng Z et al., Journal of Biomechanics, 48.14: 3859-3867, 2015.