Evaluation of Implanted Stent Occlusion Status Based on Neointimal Tissue Bioimpedance Simulations

Abstract

This paper describes the characterization of the light hole, also known as the lumen, in implanted stents affected by restenosis processes using bioimpedance (BI) as a biomarker. The presented approach will enable real-time monitoring of lumens in implanted stents. The basis of the work hereby reported is the fact that neointimal tissues involved in restenosis can be detected and measured through their impedance properties, namely, conductivity and permittivity. To exploit these properties, a 4-electrode setup for BI measurement is proposed. This setup allows study of the influence of the various tissues involved in restenosis fat, muscle, fibre, and endothelium, together with the blood, on the BI value at several frequencies. In addition, BI simulation tests were performed using the electric physics module available in COMSOL Multiphysics®. Interestingly, fat constitutes the most influential layer on the value of impedance (measured in kΩ/μm—magnitude change per micrometre of lumen occlusion). A case study using a standard stent is also presented. In this study, where the involved tissues and blood were simultaneously considered, we conducted an analysis for stable and vulnerable plaques in restenosis test situations. In this regard, the proposed method is useful to test the stent obstruction and detect potential dangerous cases due to nonstable fat accumulation.

Bioimpedance Sensing of Implanted Stent Occlusions: Smart Stent

“…The simulations carried out showed a uniform and homogenous distribution of the electric current for the non-pathological model. This is in accordance with previous partial results published in [ 11 ], where a mathematical model was developed to analytically describe the histological composition of the neointima, employing its conductivity and permittivity data.…”

“…The conditions for the blood fluid model were obtained following different models used in [ 14 , 15 ], using the Laminar Flow Analysis module of COMSOL Multiphysics with the dimensions of the artery previously shown, and the flow parameters shown in Figure 3 . The movement of the blood is an important parameter for the monitoring of impedance, and its simulation improves the model reported in [ 11 ].…”

“…The geometry of the model is shown in Figure 1 . The values used to implement that geometry, and the electrical properties of the different layers were extracted from [ 11 ] and are summarized in Table 1 , Table 2 and Table 3 .…”

“…An initial mathematical model was developed to analytically describe the histological composition of the neointima, employing its conductivity and permittivity data [ 10 ]. In another work [ 11 ], a 4-electrode setup for bioimpedance measurements was proposed. This setup allowed the study of the influence of the various tissues involved in restenosis: fat, muscle, fibre, and endothelium, together with the blood, with interesting and promising results for the local monitoring of restenosis with bioimpedance measurements.…”

3D-Printed Sensors and Actuators in Cell Culture and Tissue Engineering: Framework and Research Challenges

“…Specifically, six functional inks were fabricated based on high-conductance and biocompatible soft materials. Targeting also cardiovascular applications, different implanted devices for the monitoring of the stent occlusion status were proposed in [ 47 ], and the potential use of 3D printing technologies for the fabrication of these devices was studied in [ 48 ], highlighting specific materials, such as PEDOT:PSS or flexible printed electrodes. However, further work is still required to test biocompatibility and functional behavior of these designed devices under in vivo situations.…”