Abstract
To follow up the restenosis in arteries stented during an angioplasty is an important current clinical problem. A new approach to monitor the growth of neointimal tissue inside the stent is proposed on the basis of electrical impedance spectroscopy (EIS) sensors and the oscillation-based test (OBT) circuit technique. A mathematical model was developed to analytically describe the histological composition of the neointima, employing its conductivity and permittivity data. The bioimpedance model was validated against a finite element analysis (FEA) using COMSOL Multiphysics software. A satisfactory correlation between the analytical model and FEA simulation was achieved in most cases, detecting some deviations introduced by the thin “double layer” that separates the neointima and the blood. It is hereby shown how to apply conformal transformations to obtain bioimpedance electrical models for stack-layered tissues over coplanar electrodes. Particularly, this can be applied to characterize the neointima in real-time. This technique is either suitable as a main mechanism for restenosis follow-up or it can be combined with proposed intelligent stents for blood pressure measurements to auto-calibrate the sensibility loss caused by the adherence of the tissue on the micro-electro-mechanical sensors (MEMSs).
Highlights
IntroductionIschemic heart disease is the leading cause of morbidity and mortality in the world [1,2]
Ischemic heart disease is the leading cause of morbidity and mortality in the world [1,2].The interior of the elastic and muscular arteries shrinks, mainly by the growth of a lipid layer, causing angina chest pain and acute myocardial infarction
Analytical Model and 2D Finite Element Analysis Simulation Results the expected accuracy, given the error introduced by mathematical transformations and the ideal boundary conditions
Summary
Ischemic heart disease is the leading cause of morbidity and mortality in the world [1,2]. The interior of the elastic and muscular arteries shrinks (stenosis), mainly by the growth of a lipid layer (atherosclerosis), causing angina chest pain and acute myocardial infarction. Despite improvements to the surgery techniques and the stent design [5,6,7], there is a high probability of medium-term restenosis [8]. In [9], the use of micro-electro-mechanical pressure sensors (MEMSs) to monitor restenosis with intelligent stents is proposed. The sensors are implemented as parallel-plate capacitors: one is a fixed plate, whereas the other bends with increasing pressure.
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