Transverse wall shear stress, an index of multidirectional flow, correlated positively and significantly with atherosclerotic lesion prevalence in both immature and mature rabbit aortas.
Observational (n=17)
Does multidirectional flow (transWSS) correlate better with atherosclerotic lesion prevalence than oscillatory shear index (OSI) in rabbit aortas?
Multidirectional near-wall flow (transWSS) correlates significantly better with atherosclerotic lesion prevalence than low, oscillatory shear stress, challenging traditional biomechanical theories of atherogenesis.
The non-uniform distribution of atherosclerosis within the arterial system has been attributed to pro-atherogenic influences of low, oscillatory haemodynamic wall shear stress (WSS) on endothelial cells (EC). This theory is challenged by the changes in lesion location that occur with age in human and rabbit aortas. Furthermore, a number of point-wise comparisons of lesion prevalence and WSS have failed to support it. Here we investigate the hypothesis that multidirectional flow-characterized as the average magnitude of WSS components acting transversely to the mean vector (transWSS)-plays a key role. Maps of lesion prevalence around aortic branch ostia in immature and mature rabbits were compared with equivalent maps of time average WSS, the OSI (an index characterizing oscillatory flow) and transWSS, obtained from computational simulations; Spearman's rank correlation coefficients were calculated for aggregated data and 95% confidence intervals were obtained by bootstrapping methods. Lesion prevalence correlated positively, strongly and significantly with transWSS at both ages. Correlations of lesion prevalence with the other shear metrics were not significant or were significantly lower than those obtained for transWSS. No correlation supported the low, oscillatory WSS theory. The data are consistent with the view that multidirectional near-wall flow is highly pro-atherogenic. Effects of multidirectional flow on EC, and methods for investigating them, are reviewed. The finding that oscillatory flow has pro-inflammatory effects when acting perpendicularly to the long axis of EC but anti-inflammatory effects when acting parallel to it may explain the stronger correlation of lesion prevalence with transWSS than with the OSI.
Mohamied et al. (Tue,) conducted a observational in Atherosclerosis (n=17). Transverse wall shear stress (transWSS) vs. Time average wall shear stress (TAWSS) and Oscillatory shear index (OSI) was evaluated on Correlation between lesion prevalence and transWSS around aortic branch ostia. Transverse wall shear stress, an index of multidirectional flow, correlated positively and significantly with atherosclerotic lesion prevalence in both immature and mature rabbit aortas.