A Comprehensive Numerical Simulation on the Safety and Efficacy of Circular-Versus Trapezoidal-Shaped Intravascular Drug-Eluting Stents

Abstract

In modern days, drug-eluting stent (DES) acts as a kingpin for the treatment of coronary artery disease (CAD) and it has a dramatic reduction rate of in-stent restenosis (ISR) in compare to a bare metal stent (BMS). To replicate the drug release from therapeutic devices and its corresponding transportation in the physiological atmosphere, mathematical and computational simulations have become an effective technique. The present article is developed by a thorough comparative analysis of drug transport mechanisms between half-embedded trapezoidal-shaped and circular-shaped struts and also its optimality in stent-based drug delivery. The geometry of the implanted struts (trapezoidal-shaped and circular-shaped) is modeled in a two-dimensional axi-symmetric environment and the target lesion is considered as a single homogeneous layer with identical diffusivity. Due to the hydrostatic pressure of blood, plasma filtration is allowed through the blood-tissue interface along the transmural direction and the flow of interstitial fluid within the porous arterial wall is governed by the unsteady Navier–Stokes equation and the equation of continuity. While the drug is distributed within the arterial wall, tissue receptors grip the drug molecules, so the present study includes the binding of drug along with free drug. An unsteady convection-diffusion–reaction process demonstrates the transportation of free drug, but only reaction process manifests the transportation of bound drug. The mathematical equations of interstitial fluid flow and the transportation of drug along with pertinent initial and boundary conditions are penciled by using a two-dimensional (2D) cylindrical polar coordinate system. A staggered grid generation technique is also leveraged to discretize all the governing equations and boundary conditions, which are then successfully solved numerically by using Marker-and-Cell (MAC) method. The coefficient of variance (CV), a statistical parameter, is introduced in this present drug delivery system to access the consistency of the drug distribution. The study incorporates several necessary factors, such as drug efficacy, tissue drug content, and therapeutic effectiveness to optimize the choice of strut shape and the overall performance of the stent. To achieve the best possible outcomes, a robust sensitivity analysis of several perturbed parameters is carried out by implementing one-way ANOVA. The results highlight that, for long-term safety and efficacy, trapezoidal-shaped struts may be a good choice in compared to circular ones. Furthermore, the tailored combination of strut shape and drug delivery strategy presented herein offers a significant advancement in designing the next-generation DES.