Investigation of the influence of side-branches on wall shear stress in coronary arteries reconstructed from intravascular ultrasound

Atherosclerotic plaques are found to occur in arterial segments exposed to low wall shear stress (WSS). In order for WSS to be precisely calculated, an accurate representation of the coronary anatomy is critical. Several side-branches originate along the length of the coronary arteries, which should be included in simulations. The aim of this work is to investigate the influence of excluding the coronary side-branches on WSS and on predicting coronary artery disease progression with WSS. Three patient-specific coronary arteries were imaged using virtual histology intravascular ultrasound (VH-IVUS) at baseline and 12 months follow-up. Using the baseline images, 3D reconstructions were created and side-branches as visible in IVUS images were added to each patient. WSS was calculated for models with and without side-branches. There were large differences in absolute WSS between the models with side-branches and those without. WSS was found to be low opposite the flow divider in models with side-branches while this was not always the case in models without side-branches. There was little difference between both models in predicting plaque progression.