Sequential Vascular Structural And Fluid Dynamics Analysis Of Balloon-Expandable Stent Inside Patient-Specific Coronary Artery

Epidemiology data reveal that coronary artery disease(CAD)is one of the most common diseases throughout the world.Its prevention,diagnosis and treatment has always been the hotspot for researchers.Coronary stent deployment has been widely used in treatment of CAD.Appropriate stenting scheme is prerequisite for favorable PCI prognosis.Otherwise,it may lead to severe complications such as incomplete stent expansion,stent migration,stent thrombosis and in-stent restenosis.Due to individual differences between patients and complexity of stenosis lesion,there is not an acknowledged criterion on stenting scheme,which mainly depends on clinicians’ experience.Moreover,once a PCI scheme is performed,it may cause irreversible changes to coronary artery vessels.If the outcome is not good enough,re-stenting or surgical treatment is an expensive process with higher risk.Therefore,it will be of great clinical significance for virtual stenting technology based on finite element numerical simulation and clinical images to achieve “precise stent deployment” by combining physicians’ experience and individualized patients.This could be used to help doctors to develop better surgical plans,predict surgical outcomes and potential risk factors.Studies also show that stent deployment could improve artery vessel and restore normal blood flow.At the same time,it could cause mechanical damage to the vessel wall,disturb the fluid environments,which maybe a potential risk factor for long-term instent restenosis.Hence,it is of great significance to accurately evaluate the biomechanical properties of vessel wall during stent procedures.Given this,we intend to comprehensively study the stent/vascular structural mechanics and blood flow changes through sequential structural and hemodynamics numerical analysis.Firstly,we simulated the virtual stenting deployment in ABAQUS/Explict module based on a real clinical case and validated the reliability and veracity of simulation with clinical images;secondly,we assessed the interaction between balloon/stent and vascular wall as well as their morphological changes and stress distribution at different time points;then,fluid domain model was established according to the results of structural analysis and be used in transient hemodynamic analysis to study the hemodynamics changes after stent implantation;at last,we investigated the transient edge vascular response during stenting procedure in assessment of instant altered geometry and biomechanical changes through virtual stenting technology.Validation analysis showed that numerical simulation was in good agreement with clinical OCT images,which verified the feasibility of virtual technology in simulating stent implantation.The results of structural analysis showed that: balloon pre-dilatation could preliminarily reshape the stenotic vascular lumen;stent deployment straightened the vascular wall and changed lumen diameter and area,especially in the stenotic sites;the maximal principle stress mainly concentrated in the contact area between stent struts and vascular wall and was not uniform along the circumferential direction;the peak Mises stress of stent occurred in the corner of the strut and at the connection between crowns.Results from transient CFD analysis showed that stent deployment increased the wall shear stress gradient and formed low WSS area near stent strut;stent strut changed the blood flow direction,resulting in flow separation as well as low velocity area.Also,diameter and ellipticity varied along the longitudinal direction of the edge vascular wall and more than 90% of the changes concentrated within 2 mm range adjacent to both stent ends;stress mismatch occurred along the longitudinal direction of edge vascular wall.In this paper,we studied individualized coronary stent deployment procedure as well as the post-stent deformation behavior and biomechanical behavior,providing reference for assessing surgical plan and illuminating biomechanical mechanism of instent restenosis.At the same time,it may contribute to novel stent development and optimization design,assist doctor to make better surgical scheme as well as predict surgical results.