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Session: Poster session I
Session starts: Thursday 24 January, 15:00

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Giuseppe De Nisco (Politecnico di Torino)
Annette M. Kok (Erasmus MC)
Claudio Chiastra (Politecnico di Milano)
Diego Gallo (Politecnico di Torino)
Ayla Hoogendoorn (Erasmus MC)
Francesco Migliavacca (Politecnico di Milano)
Umberto Morbiducci (Politecnico di Torino)
Jolanda J. Wentzel (Erasmus MC)

Abstract:
INTRODUCTION In recent years a distinguishable arterial intravascular blood flow feature, helical flow (HF), has been identified as an atheroprotective hemodynamic phenotype, because of its capability to suppress flow disturbances[1,2,3]. In this study, we (1) describe in depth for the first time helical blood flow in swine coronary arteries, and (2) explore the existence of associations between helical flow descriptors and descriptors of disturbed shear stress. METHODS The lumen geometry of 30 coronary arteries (10 left anterior descending, 10 left circumflex, and 10 right coronary arteries) of adult low density lipoprotein receptors mutation pigs was acquired at the early stage of a high fat diet protocol and reconstructed from fusion of CT angiography and IVUS images[4]. Personalized computational hemodynamics approach was applied to solve the discretized Navier-Stokes equations, with swine-specific flow rates at inflow and outflow sections (at the side branches) obtained from Doppler velocity measurements. The luminal surface averaged values of three “established” descriptors of low/oscillatory wall shear stress (WSS), i.e. the time-averaged WSS (TAWSS), the oscillatory shear index (OSI), and the relative residence time (RRT), and descriptors quantifying WSS multidirectionality[5], were computed in each vessel. Helicity-based hemodynamic descriptors proposed elsewhere[1] were computed to describe helical flow structure in coronary arteries. Possible associations between HF and WSS-based descriptors were explored by Spearman correlation coefficient ρ, significance was assumed for p<0.05. RESULTS It was observed that distinguishable counter-rotating HF structures characterize the intravascular hemodynamics of all the investigated coronary arteries, although with different intensity. Significant associations were observed between helicity intensity h2 and WSS-descriptors. In particular, h2 was found to be strongly positively correlated with TAWSS (ρ=0.92), i.e. high helicity intensity values imply higher, more atheroprotective, TAWSS values. A result of interest is that the investigated coronary arteries resulted to be exposed to a moderately-to-scarcely multidirectional WSS. CONCLUSIONS This study demonstrates that HF is naturally present in healthy coronary arteries and that, as in other arteries[1,3], it has an atheroprotective nature, because of its positive influence on pro-atherogenic hemodynamic WSS-descriptors. Future analysis will clarify if HF in coronary arteries is also correlated to lower prevalence of atherosclerosis.