Computational fluid dynamics applied to virtually deployed drug-eluting coronary bioresorbable scaffolds: Clinical translations derived from a proof-of-concept.

Bill D Gogas,Girum Mekonnen,Olivia Y Hung,Emad Rasoul-Arzrumly,Gaetano Esposito,Boyi Yang,Don Giddens,Spencer B King,Mosaab Awad,Marina Piccinelli,Tiziano Passerini,Alessandro Veneziani,Michael Mcdaniel,Beth Holloway,Habib Samady

doi:10.5339/gcsp.2014.56

Abstract

Background: Three-dimensional design simulations of coronary metallic stents utilizing mathematical and computational algorithms have emerged as important tools for understanding biomechanical stent properties, predicting the interaction of the implanted platform with the adjacent tissue, and informing stent design enhancements. Herein, we demonstrate the hemodynamic implications following virtual implantation of bioresorbable scaffolds using finite element methods and advanced computational fluid dynamics (CFD) simulations to visualize the device-flow interaction immediately after implantation and following scaffold resorption over time. Methods and Results: CFD simulations with time averaged wall shear stress (WSS) quantification following virtual bioresorbable scaffold deployment in idealized straight and curved geometries were performed. WSS was calculated at the inflow, endoluminal surface (top surface of the strut), and outflow of each strut surface post-procedure (stage I) and at a time point when 33% of scaffold resorption has occurred (stage II). The average WSS at stage I over the inflow and outflow surfaces was 3.2 and 3.1 dynes/cm2 respectively and 87.5 dynes/cm2 over endoluminal strut surface in the straight vessel. From stage I to stage II, WSS increased by 100% and 142% over the inflow and outflow surfaces, respectively, and decreased by 27% over the endoluminal strut surface. In a curved vessel, WSS change became more evident in the inner curvature with an increase of 63% over the inflow and 66% over the outflow strut surfaces. Similar analysis at the proximal and distal edges demonstrated a large increase of 486% at the lateral outflow surface of the proximal scaffold edge. Conclusions: The implementation of CFD simulations over virtually deployed bioresorbable scaffolds demonstrates the transient nature of device/flow interactions as the bioresorption process progresses over time. Such hemodynamic device modeling is expected to guide future bioresorbable scaffold design.

Highlights

Despite tremendous innovations in platform design such as strut thickness reductions, use of novel antiproliferative agents, coatings with bioresorbable polymers or abluminal drug coatings,[1] the utilization of a permanent metallic prosthesis for the treatment of significant coronary artery disease remains a precipitating factor for sustained vascular inflammation, in-stent neoatherosclerosis and impaired vasomotor function.[2]
The implementation of computational fluid dynamics (CFD) simulations over virtually deployed bioresorbable scaffolds demonstrates the transient nature of device/flow interactions as the bioresorption process progresses over time
We examined 2 stages in each vessel model Stage I: post-implantation, where the strut thickness is 0.015 cm (150 mm); the distance between each strut 0.1 cm, the degree of embedding in the vessel wall 50% simulating half-embedded struts, and the radius of the vessel lumen 0.15 cm and stage II: follow-up, where the strut thickness is reduced to 0.010 cm (67%) reflecting a 33% strut bioresorption and the radius of the lumen reduced to 0.14975 cm simulating some degree of bioresorption and neointimal hyperplasia (NIH), respectively

Summary

Introduction

Despite tremendous innovations in platform design such as strut thickness reductions, use of novel antiproliferative agents, coatings with bioresorbable polymers or abluminal drug coatings,[1] the utilization of a permanent metallic prosthesis for the treatment of significant coronary artery disease remains a precipitating factor for sustained vascular inflammation, in-stent neoatherosclerosis and impaired vasomotor function.[2]. Several drug-eluting bioresorbable devices, such as the Absorb bioresorbable vascular scaffold (Abbott Vascular, SC, Calif.), the DESolve bioresorbable scaffold, (Elixir Medical, Sunnyvale, Calif.), and the Drug Eluting Absorbable Metal Scaffold (DREAMS) (Biotronik, Bulach, Switzerland) have been clinically tested in first-in-man studies utilizing multi modality imaging techniques showing encouraging clinical results up to 3-years. Conclusions: The implementation of CFD simulations over virtually deployed bioresorbable scaffolds demonstrates the transient nature of device/flow interactions as the bioresorption process progresses over time. Such hemodynamic device modeling is expected to guide future bioresorbable scaffold design

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