Virtual reality simulation for the optimization of endovascular procedures : current perspectives

Endovascular technologies are rapidly evolving, often - requiring coordination and cooperation between clinicians and technicians from diverse specialties. These multidisciplinary interactions lead to challenges that are reflected in the high rate of errors occurring during endovascular procedures. Endovascular virtual reality (VR) simulation has evolved from simple benchtop devices to full physic simulators with advanced haptics and dynamic imaging and physiological controls. The latest developments in this field include the use of fully immersive simulated hybrid angiosuites to train whole endovascular teams in crisis resource management and novel technologies that enable practitioners to build VR simulations based on patient-specific anatomy. As our understanding of the skills, both technical and nontechnical, required for optimal endovascular performance improves, the requisite tools for objective assessment of these skills are being developed and will further enable the use of VR simulation in the training and assessment of endovascular interventionalists and their entire teams. Simulation training that allows deliberate practice without danger to patients may be key to bridging the gap between new endovascular technology and improved patient outcomes

Towards a Digital Twin of Coronary Stenting: A Suitable and Validated Image-Based Approach for Mimicking Patient-Specific Coronary Arteries

Considering the field of application involving stent deployment simulations, the exploitation of a digital twin of coronary stenting that can reliably mimic the patient-specific clinical reality could lead to improvements in individual treatments. A starting step to pursue this goal is the development of simple, but at the same time, robust and effective computational methods to obtain a good compromise between the accuracy of the description of physical phenomena and computational costs. Specifically, this work proposes an approach for the development of a patient-specific artery model to be used in stenting simulations. The finite element model was generated through a 3D reconstruction based on the clinical imaging (coronary Optical Coherence Tomography (OCT) and angiography) acquired on the pre-treatment patient. From a mechanical point of view, the coronary wall was described with a suitable phenomenological model, which is consistent with more complex constitutive approaches and accounts for the in vivo pressurization and axial pre-stretch. The effectiveness of this artery modeling method was tested by reproducing in silico the stenting procedures of two clinical cases and comparing the computational results with the in vivo lumen area of the stented vessel

Computational modelling of stent deployment and mechanical performance inside human atherosclerotic arteries

Atherosclerosis is the obstruction of blood stream caused by the formation of fatty plaques (stenosis) within human blood vessels. It is one of the most common cardiovascular conditions and the primary cause of death in developed countries. Nowadays stenting is a standard treatment for this disease and has been undergoing a rapid technological development. The aim of this PhD is to simulate the deployment of stents within atherosclerotic arteries in order to understand the mechanical performance of these devices. To this purpose, specific objectives were identified to study: (i) the effects of stent design, material and coating on stent deployment; (ii) the influence of balloon type, arterial constraints and vessel constitutive models in stenting simulation; (iii) the importance of plaque thickness, stenosis asymmetry and vessel curvature during the process of stent deployment; (iv) the necessity of considering vessel anisotropy and post-deployment stresses to assess stents mechanical behaviour; (v) the performance of biodegradable polymeric stents in comparison with metallic stents. Finite element (FE) analyses were employed to model the deployment of balloon-expandable stents. The balloon-stent-artery system was generated and meshed using finite element package Abaqus. Individual arterial layer and stenosis were modelled using hyperelastic Ogden model, while elastic-plastic behaviour with nonlinear hardening was used to describe the material behaviour of stents. The expansion of the stent was obtained by application of pressure inside the balloon, with hard contacts defined between stent, balloon and artery. The FE model was evaluated by mesh sensitivity study and further validated by comparison with published work. Comparative study between different commercially available stents (i.e. Palmaz-Schatz, Cypher, Xience and Endeavor stents) showed that open-cell design tends to have easier expansion and higher recoiling than closed-cell design, with lower stress level on the plaque after deployment. Also, stents made of materials with lower yield stress and weaker strain hardening experience higher deformation and recoiling, but less post-deployment stresses. Folded balloon produces sustained stent expansion under a lower pressure when compared to rubber balloon, with also increased stress level on the stent and artery. Simulations with different arterial constraints showed that stress on the plaque-artery system is higher for a free artery as a result of more severe stretch. Study of arterial constitutive models showed that saturation of expansion could not be noticed for models that neglect the second stretch invariant in the strain energy potential. Stent expansion is highly affected by plaque thickness, and stresses and recoiling increased considerably with the increasing level of stenosis. Asymmetry of the plaque causes non-uniform stent expansion and high levels of vessel wall stresses are developed in the regions covered by thin layer of plaque. Also, a reduction in stent expansion is observed with the increase of artery curvature, accompanied by an elevation of stresses in the plaque and arterial layers. Vessel anisotropic behaviour reduces the system expansion at peak pressure, and also lowers recoiling effect significantly. The post-deployment stresses caused by stent expansion increase the system flexibility during in-plane bending and radial compression. Comparative study of a PLLA stent (Elixir) and a Co-Cr alloy stent (Xience) showed that polymeric stent has a lower expansion rate and a reduction in final expansion than metallic stent

Review of patient-specific simulations of transcatheter aortic valve implantation

International audienceTranscatheter Aortic Valve Implantation (TAVI) accounts for one of the most promising new cardiovascular procedures. This minimally invasive technique is still at its early stage and is constantly developing thanks to imaging techniques, computer science, biomechanics and technologies of prosthesis and delivery tools. As a result, patient-specific simulation can find an exciting playground in TAVI. It canexpress its potential by providing the clinicians with powerful decision support, offering great assistance in their workflow. Through a review of the current scientific field, we try to identify the challenges and future evolutions of patient-specific simulation for TAVI. This review article is an attempt to summarize and coordinate data scattered across the literature about patient-specific biomechanical simulation for TAVI

Finite Element Analysis to Study Percutaneous Heart Valves

Communications engineering / telecommunication

Modeling of an implantable device for remote arterial pressure measurement

Cardiovascular diseases are the leading causes of illness and death in Europe, having a major impact on healthcare costs. An intelligent stent (e-stent), capable of obtaining and transmitting measurements of physiological parameters, can be a useful tool for real-time monitorization of arterial blockage without patient hospitalization. In this paper, a behavioral model of a pressure sensing-based e-stent is proposed and simulated under several restenosis conditions. Special attention has been given to the need of an accurate fault model, obtained from realistic finite-element simulations, to ensure long-term reliability; particularly for those faults whose behavior cannot be described by usual analytical models

Implantable Sensor System for Remote Detection of a Restenosis Condition

Part 7: Perceptional SystemsInternational audienceThe increase of life expectancy in the European Union, and the high risk of cardiovascular diseases associated with age, are some of the main factors to contribute to the rise of healthcare costs. An intelligent stent (e-stent), capable of obtaining and transmitting real-time measurements of physiological parameters for its clinical consultation, can be a useful tool for long-term monitoring, diagnostic, and early warning system for arterial blockage without patient hospitalization. In this paper, a behavioural model of capacitive Micro-Electro-Mechanical (MEMS) pressure sensor is proposed and simulated under several restenosis conditions. Special attention has been given to the need of an accurate fault model, obtained from realistic finite-element simulations,to ensure long-term reliability; particularly for those faults whose behavior cannot be easily described by an analytical model