Patient-specific simulations of stenting procedures in coronary bifurcations: Two clinical cases
Introduction
In the last decade, several numerical models have been implemented to simulate different stenting procedures and provide new information about their biomechanical influence on the surrounding vascular environment [1]. The main advantage of these models is the ability of assessing several quantities hard to measure with in vivo or in vitro tests such as the stresses in the arterial wall or the mechanical deformation of the devices [2], [3]. In literature, these quantities have been associated with poor clinical outcomes [4], [5]. In particular, post-stenting adverse events include thrombus formation within the stented segment and/or intimal hyperplasia (the rapid proliferation of smooth muscle cells in vessel wall) [6] which, in the extreme, leads to restenosis (re-occlusion of the vessel).
Currently, important limitations still preclude the routine application of computational models in the clinical field. Among these limits, the majority of numerical studies until today is still based on highly idealized geometries and only aims at replicating standard stenting procedures [7], [8], [9], [10]. Therefore, such studies can only provide universal guidelines and not patient-specific indications for the planning of each treatment. The possibility to compare different procedural options considering the specific anatomical and mechanical properties of each patient before its treatment might help the improvement of the interventional planning and clinical outcome. However, recent developments in coronary imaging have paved the way to new methods that are able to create realistic image-based reconstructions of vascular districts [11], potentially useful for patient-specific simulations of stenting procedures.
In this light, the aim of this work is to prove the feasibility of implementing patient-specific structural models starting from image-based reconstructions of atherosclerotic coronary arteries. The replicas of two real clinical cases are simulated by following the procedural indications of the physician who actually performed the interventions. In particular, the two studied cases involved coronary bifurcations of the left anterior descending (LAD) coronary artery since such regions are very critical from a biomechanics point of view [12] and are still affected by lower clinical and procedural outcomes [13]. Interventions were performed at University Hospital Doctor Peset in Valencia (Spain) and patients were treated with a provisional side branch (PSB) stenting without final kissing balloon. This strategy consists of deploying a stent in the main branch (MB) across the bifurcation followed by the optional treatment of the side branch (SB) in the case of sub-optimal clinical results [14]. Pre-stenting acquisitions with computed tomography angiography (CTA) and conventional coronary angiography (CCA) are used to generate image-based models of the atherosclerotic bifurcations [15] that are subsequently discretized with fully hexahedral meshes. Atherosclerotic plaques are included in the model, monitoring the distance from each node to the centerline of the external wall. Curvature and tortuosity of the coronaries entail the development of preliminary structural analyses to accurately crimp and advance the devices to the correct position. Afterwards, stressed configurations of the devices are used within the final structural simulations, replicating the actual stenting procedures by means of a finite element commercial code [9]. Lastly, for one case, the final geometrical configuration obtained in silico is compared with the image-based reconstruction of post-stenting geometry providing a qualitative validation of the proposed numerical approach.
Section snippets
Image-based coronary bifurcation models
Two clinical cases of adult females are investigated in this work, after informed patient consent and approval of the hospital ethical committee for this study. In both cases, the patients underwent percutaneous coronary stent implantation. In particular, the first case investigated (case A) involves the proximal section of the LAD while in the second case (case B) both the proximal and mid part of LAD are included. Pre-treatment CCA and CTA are used to reconstruct the internal surfaces of the
Choice of the solution scheme
The ABAQUS finite element commercial code includes two different tools to solve structural problems: ABAQUS/Standard and ABAQUS/Explicit. For several analyses, it is clear which solver should be used but in some cases, such as the quasi-static non-linear problems investigated in this study, the choice is not trivial [24]. Each strategy has its own advantages and modeling difficulties and several studies have been recently published to compare the two approaches [25], [26], [27], [28].
In this
Conclusion
This work shows the feasibility of implementing a patient-specific virtual model replicating two actual clinical cases. This step may be considered a step forward toward the routine application of such models in the clinical field that, however, is still limited by some restrictions such as the computational cost and complex preparation of the models itself. In both simulations, the straightening of the arterial wall due to stent implantation is obtained, in agreement with previous experimental
Conflict of interest
The authors declare that they have no competing interests in this study.
Ethical approval
“Dr. Peset” Hospital Ethical Committee approval was obtained on 30/06/2010. Local Code: 19/10. Patients gave informed consent to the work on their anonymous image data.
Acknowledgements
Authors affiliated to Politecnico di Milano are supported by the projects “RT3S-Real Time Simulation for Safer vascular Stenting” funded by the European Commission and “Development of hybrid magnesium degradable stents with polymeric coating for medical application” funded by the Fondazione CARITRO. Authors affiliated to UPF and Dr. Peset are partially funded by a CDTI CENIT-cvREMOD grant of the Spanish Ministry of Science and Innovation. R.C. is also funded by a Beatriu de Pinòs post-doctoral
References (41)
- et al.
Predicting neointimal hyperplasia in stented arteries using time-dependant computational fluid dynamics: a review
Comput Biol Med
(2010) - et al.
Pathobiologic responses to stenting
Am J Cardiol
(1998) - et al.
Assessment of tissue prolapse after balloon-expandable stenting: influence of stent cell geometry
Med Eng Phys
(2009) - et al.
Finite element analysis of side branch access during bifurcation stenting
Med Eng Phys
(2009) - et al.
Left anterior descending coronary artery wall thickness measured by high-frequency transthoracic and epicardial echocardiography includes adventitia
Am J Cardiol
(2003) - et al.
Static circumferential tangential modulus of human atherosclerotic tissue
J Biomech
(1994) - et al.
Comparison of the implicit and explicit finite element methods using crystal plasticity
Comput Mater Sci
(2007) - et al.
Comparison of implicit and explicit finite element methods for dynamic problems
J Mater Proc Technol
(2000) - et al.
Coronary stent implantation changes 3-D vessel geometry and 3-D shear stress distribution
J Biomech
(2000) - et al.
Longitudinal straightening effect of stents is an additional predictor for major adverse cardiac events Austrian Wiktor Stent Study Group and European Paragon Stent Investigators
J Am Coll Cardiol
(2000)
Numerical investigation of the intravascular coronary stent flexibility
J Biomech
Impact of stent overlap on angiographic and long-term clinical outcome in patients undergoing drug-eluting stent implantation
J Am Coll Cardiol
Incidence and predictors of drug-eluting stent fracture in human coronary artery a pathologic analysis
J Am Coll Cardiol
Computational fluid dynamics of stented coronary bifurcations studied with a hybrid discretization method
Eur J Mech B: Fluids
Computational structural modeling of coronary stent deployment: a review
Comput Methods Biomech Biomed Eng
Migration of adventitial myofibroblasts following vascular balloon injury: insights from in vivo gene transfer to rat carotid arteries
Cardiovasc Res
Serial follow-up after optimized ultrasound-guided deployment of Palmaz–Schatz stents in-stent neointimal proliferation without significant reference segment response
Circulation
Modeling of the provisional side-branch stenting approach for the treatment of atherosclerotic coronary bifurcations: effects of stent positioning
Biomech Model Mechanobiol
Local hemodynamic changes caused by main branch stent implantation and subsequent virtual side branch balloon angioplasty in a representative coronary bifurcation
J Appl Physiol
Cited by (97)
Residence time in complex left main bifurcation disease after stenting
2024, Cardiovascular Revascularization MedicineA review on the use of finite element simulations for structural analyses of coronary stenting: What can we do nowadays and what do we need to move forward?
2023, European Journal of Mechanics, A/SolidsEffects of leaflet curvature and thickness on the crimping stresses in transcatheter heart valve
2023, Journal of BiomechanicsComputational analysis of the effects of geometric irregularities on the interaction of an additively manufactured 316L stainless steel stent and a coronary artery
2022, Journal of the Mechanical Behavior of Biomedical MaterialsCitation Excerpt :Since stent-artery interaction has a strong influence on the long-term clinical success of stent treatment, its analysis has become an integral part of stent research and development. To reduce the number of experimental studies as well as ethically questionable animal experiments, computational analyses of stent-artery interaction based on structural mechanics as well as fluid dynamics were established, enabling the identification of predictors for ISR (Timmins et al., 2008, 2011; Wu et al., 2007; Morlacchi et al., 2013; Prendergast et al., 2003; Auricchio et al., 2011; Wei et al., 2019). Within these simulations, a stent model is virtually expanded in an artery, and the interaction of the stent with the arterial wall or the influence of the stent on hemodynamics is assessed.
Impact of stent malapposition on intracoronary flow dynamics: An optical coherence tomography-based patient-specific study
2021, Medical Engineering and Physics