European Bifurcation Club 2019, EBC 2019 - Barcelona, Spain NEWS 1 Learnings From the Bench and a Thrombogenicity Model Author: Nicolas Foin, MSc, PhD, National Heart Research Institute Singapore; Philips Healthcare, Belgium LEARNINGS FROM THE BENCH Bench models allow to study questions in controlled and reproducible experimental environments Make use tools such as Micro-CT, Radial & Longitudinal Strength tes;ng, 3D printing, Perfusion test, Histology, SEM Microscopy. LIMITATIONS It can only provide a partial model to investigate a question and cannot mimic the entire tissue /plaque characteristics and in-vivo biological response. Results can not always be transposed directly to in-vivo situations and should be interpreted with caution. Bench models complement, but do not replace clinical/imaging studies SUMMARY Stent underexpansion and stent malapposition distances affect flow disturbances and shear rate in a dose-dependent relation. Severe malapposition (ISA distance > 300 um) create higher shear rate with persitent malapposition + uncovered strut at follow-up. In-vitro experiments with perfused blood suggest that large malapposed stent segment create potential sites for platelet adhesion and clot development. Stent optimisation (expansion and apposition) with appropriate sizing, post-dilatation and imaging can improve local hemodynamic environment and reduce area of high shear disturbance.
European Bifurcation Club 2014, EBC 2014 - Bordeaux, France BIFURCATION STENTING: LEARNING FROM BENCH AND SIMULATION Stent strut malapposition: insights from flow simulations and OCT imaging Author: Nicolas Foin, MD, PhD, National Heart Centre Singapore, Duke-NUS QUESTIONS How are blood flow patterns and shear rate affected by different degree of stent malapposition? How does baseline flow around ISA strut affect coverage at FU High shear and delayed coverage: are both contributing factors to thrombogenicity observed with ISA? METHODS Computer Model of different strut-wall malapposition distances, flow patterns and shear rates evaluated by CFD In-vivo:ISA and strut coverage (% uncovered, thickness) assessed sequentially in-vivo by OCT at both baseline and FU Comparison of shear patterns with OCT FU coverage response SUMMARY Strut-wall malapposition distances affect flow disturbances and shear rate in a dose-dependent relation. OCT sequential study revealed that baseline ISA is mostly resolved and covered at FU for strut ISA distance < 300 um More severe malapposition (ISA distance > 300 um) create higher shear disturbance with significantly higher rate of persitent malapposition and uncovered strut at FU. Strut thickness influence re-endothelialisation as well as shear rate disturbance: for minimal shear rate, thinner strut is better. Further in-vivo studies are required to evaluate the impact of flow on neointimal healing and adverse events.