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Bioengineering
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Advances in Computational Modelling of Abdominal Aortic Aneurysm
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Advances in Computational Modelling of Abdominal Aortic Aneurysm

A special issue of Bioengineering (ISSN 2306-5354). This special issue belongs to the section "Biomedical Engineering and Biomaterials".

Deadline for manuscript submissions: closed (30 September 2023) | Viewed by 5115

Special Issue Editors

Dr. Konstantinos Tzirakis

E-Mail Website
Guest Editor
Department of Mechanical Engineering, Hellenic Mediterranean University, 71410 Heraklion, Greece
Interests: computational fluid dynamics; finite element analysis; non-Newtonian rheology; abdominal aortic aneurysm
Dr. Nikolaos Kontopodis

E-Mail Website
Guest Editor
Vascular Surgery Department, Medical School, University of Crete, 71003 Heraklion-Crete, Greece
Interests: vascular/endovascular surgery; arterial/abdominal aortic aneurysms; non-Newtonian rheology

Special Issue Information

Dear Colleagues,

Abdominal Aortic Aneurysm (AAA) is a disease of the elderly, commonly encountered in the aging population of developed countries. Due to its unique geometric configuration, leading to particular patterns of blood flow and the development of various forces, these lesions present a significant hemodynamic and biomechanical background and, as such, have received attention from a research perspective through computational modelling.

This Special Issue on “Advances in Computational Modelling of Abdominal Aortic Aneurysm” will focus on the computational methods used to study the hemodynamic and biomechanical variables that develop inside AAAs and identify possible correlations with the risk of rupture. The maximum diameter criterion that is currently used as the main (if not the sole) determinant of rupture and, therefore, the need for intervention, was proven to be inadequate for accurate rupture risk prediction at a patient-specific level. Numerical simulations can provide an insight into the physiology and pathophysiology of these lesions and possibly assist in the delineation of their natural history. The individualized characteristics of AAAs may further define the risk of rupture beyond the universal maximum diameter criterion. Moreover, the treatment of AAAs with open surgical or endovascular techniques may present a variable hemodynamic performance with various possible configurations, each one presenting specific advantages and disadvantages. Computational modelling can be employed to study these treatment modalities to provide insight into their comparative efficacy and, in this regard, guide clinical practice.

Topics of interest for this Special Issue include, but are not limited to, the following:

  • The role of peak wall stress in the natural history of AAAs;
  • The relevancy of wall shear stress in the prognosis of AAAs;
  • The effect of model assumptions on the results of numerical simulations;
  • The development of novel biomechanical and hemodynamic rupture risk markers;
  • The comparison of various grafts and endografts during endovascular or surgical repair of AAAs.

Dr. Konstantinos Tzirakis
Dr. Nikolaos Kontopodis
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Bioengineering is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2700 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • abdominal aortic aneursym
  • computational fluid dynamics
  • numerical methods
  • mathematical modelling
  • blood flow
  • non-Newtonian rheology

Published Papers (4 papers)

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Research

20 pages, 3186 KiB  
Article
Computational Study of Abdominal Aortic Aneurysm Walls Accounting for Patient-Specific Non-Uniform Intraluminal Thrombus Thickness and Distinct Material Models: A Pre- and Post-Rupture Case
by Platon Sarantides, Anastasios Raptis, Dimitrios Mathioulakis, Konstantinos Moulakakis, John Kakisis and Christos Manopoulos
Bioengineering 2024, 11(2), 144; https://doi.org/10.3390/bioengineering11020144 - 31 Jan 2024
Viewed by 824
Abstract
An intraluminal thrombus (ILT) is present in the majority of abdominal aortic aneurysms, playing a crucial role in their growth and rupture. Although most computational studies do not include the ILT, in the present study, this is taken into account, laying out the [...] Read more.
An intraluminal thrombus (ILT) is present in the majority of abdominal aortic aneurysms, playing a crucial role in their growth and rupture. Although most computational studies do not include the ILT, in the present study, this is taken into account, laying out the whole simulation procedure, namely, from computed tomography scans to medical image segmentation, geometry reconstruction, mesh generation, biomaterial modeling, finite element analysis, and post-processing, all carried out in open software. By processing the tomography scans of a patient’s aneurysm before and after rupture, digital twins are reconstructed assuming a uniform aortic wall thickness. The ILT and the aortic wall are assigned different biomaterial models; namely, the first is modeled as an isotropic linear elastic material, and the second is modeled as the Mooney–Rivlin hyperelastic material as well as the transversely isotropic hyperelastic Holzapfel–Gasser–Ogden nonlinear material. The implementation of the latter requires the designation of local Cartesian coordinate systems in the aortic wall, suitably oriented in space, for the proper orientation of the collagen fibers. The composite aneurysm geometries (ILT and aortic wall structures) are loaded with normal and hypertensive static intraluminal pressure. Based on the calculated stress and strain distributions, ILT seems to be protecting the aneurysm from a structural point of view, as the highest stresses appear in the thrombus-free areas of the aneurysmal wall. Full article
(This article belongs to the Special Issue Advances in Computational Modelling of Abdominal Aortic Aneurysm)
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12 pages, 4593 KiB  
Article
Modelling and Simulation of the Combined Use of IABP and Impella as a Rescue Procedure in Cardiogenic Shock: An Alternative for Non-Transplant Centres?
by Beatrice De Lazzari, Massimo Capoccia, Roberto Badagliacca and Claudio De Lazzari
Bioengineering 2023, 10(12), 1434; https://doi.org/10.3390/bioengineering10121434 - 17 Dec 2023
Viewed by 867
Abstract
The treatment of critically ill patients remains an evolving and controversial issue. Mechanical circulatory support through a percutaneous approach for the management of cardiogenic shock has taken place in recent years. The combined use of IABP and the Impella 2.5 device may have [...] Read more.
The treatment of critically ill patients remains an evolving and controversial issue. Mechanical circulatory support through a percutaneous approach for the management of cardiogenic shock has taken place in recent years. The combined use of IABP and the Impella 2.5 device may have a role to play for this group of patients. A simulation approach may help with a quantitative assessment of the achievable degree of assistance. In this paper, we analyse the interaction between the Impella 2.5 pump applied as the LVAD and IABP using the numerical simulator of the cardiovascular system developed in our laboratory. Starting with pathological conditions reproduced using research data, the simulations were performed by setting different rotational speeds for the LVAD and driving the IABP in full mode (1:1) or partial mode (1:2, 1:3 and 1:4). The effects induced by drug administration during the assistance were also simulated. The haemodynamic parameters under investigation were aa follows: mean aortic pressure, systolic and diastolic aortic pressure, mean pulmonary arterial pressure, mean left and right atrial pressure, cardiac output, cardiac index, left and right ventricular end-systolic volume, left ventricular end-diastolic volume and mean coronary blood flow. The energetic variables considered in this study were as follows: left and right ventricular external work and left and right atrial pressure-volume area. The outcome of our simulations shows that the combined use of IABP and Impella 2.5 achieves adequate support in the acute phase of cardiogenic shock compared to each standalone device. This would allow further stabilisation and transfer to a transplant centre should the escalation of treatment be required. Full article
(This article belongs to the Special Issue Advances in Computational Modelling of Abdominal Aortic Aneurysm)
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16 pages, 73817 KiB  
Article
Influence of Blood Rheology and Turbulence Models in the Numerical Simulation of Aneurysms
by Alberto Brambila-Solórzano, Federico Méndez-Lavielle, Jorge Luis Naude, Gregorio Josué Martínez-Sánchez, Azael García-Rebolledo, Benjamín Hernández and Carlos Escobar-del Pozo
Bioengineering 2023, 10(10), 1170; https://doi.org/10.3390/bioengineering10101170 - 08 Oct 2023
Cited by 1 | Viewed by 1386
Abstract
An aneurysm is a vascular malformation that can be classified according to its location (cerebral, aortic) or shape (saccular, fusiform, and mycotic). Recently, the study of blood flow interaction with aneurysms has gained attention from physicians and engineers. Shear stresses, oscillatory shear index [...] Read more.
An aneurysm is a vascular malformation that can be classified according to its location (cerebral, aortic) or shape (saccular, fusiform, and mycotic). Recently, the study of blood flow interaction with aneurysms has gained attention from physicians and engineers. Shear stresses, oscillatory shear index (OSI), gradient oscillatory number (GON), and residence time have been used as variables to describe the hemodynamics as well as the origin and evolution of aneurysms. However, the causes and hemodynamic conditions that promote their growth are still under debate. The present work presents numerical simulations of three types of aneurysms: two aortic and one cerebral. Simulation results showed that the blood rheology is not relevant for aortic aneurysms. However, for the cerebral aneurysm case, blood rheology could play a relevant role in the hemodynamics. The evaluated turbulence models showed equivalent results in both cases. Lastly, a simulation considering the fluid–structure interaction (FSI) showed that this phenomenon is the dominant factor for aneurysm simulation. Full article
(This article belongs to the Special Issue Advances in Computational Modelling of Abdominal Aortic Aneurysm)
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23 pages, 4812 KiB  
Article
Intraluminal Thrombus Characteristics in AAA Patients: Non-Invasive Diagnosis Using CFD
by Djelloul Belkacemi, Miloud Tahar Abbes, Mohammad Al-Rawi, Ahmed M. Al-Jumaily, Sofiane Bachene and Boualem Laribi
Bioengineering 2023, 10(5), 540; https://doi.org/10.3390/bioengineering10050540 - 27 Apr 2023
Cited by 5 | Viewed by 1608
Abstract
Abdominal aortic aneurysms (AAA) continue to pose a high mortality risk despite advances in medical imaging and surgery. Intraluminal thrombus (ILT) is detected in most AAAs and may critically impact their development. Therefore, understanding ILT deposition and growth is of practical importance. To [...] Read more.
Abdominal aortic aneurysms (AAA) continue to pose a high mortality risk despite advances in medical imaging and surgery. Intraluminal thrombus (ILT) is detected in most AAAs and may critically impact their development. Therefore, understanding ILT deposition and growth is of practical importance. To assist in managing these patients, the scientific community has been researching the relationship between intraluminal thrombus (ILT) and hemodynamic parameters wall shear stress (WSS) derivatives. This study analyzed three patient-specific AAA models reconstructed from CT scans using computational fluid dynamics (CFD) simulations and a pulsatile non-Newtonian blood flow model. The co-localization and relationship between WSS-based hemodynamic parameters and ILT deposition were examined. The results show that ILT tends to occur in regions of low velocity and time-averaged WSS (TAWSS) and high oscillation shear index (OSI), endothelial cell activation potential (ECAP), and relative residence time (RRT) values. ILT deposition areas were found in regions of low TAWSS and high OSI independently of the nature of flow near the wall characterized by transversal WSS (TransWSS). A new approach is suggested which is based on the estimation of CFD-based WSS indices specifically in the thinnest and thickest ILT areas of AAA patients; this approach is promising and supports the effectiveness of CFD as a decision-making tool for clinicians. Further research with a larger patient cohort and follow-up data are needed to confirm these findings. Full article
(This article belongs to the Special Issue Advances in Computational Modelling of Abdominal Aortic Aneurysm)
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