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Gasparotti E, Vignali E, Quartieri S, Lazzeri R, Celi S. Numerical investigation on circular and elliptical bulge tests for inverse soft tissue characterization. Biomech Model Mechanobiol 2023; 22:1697-1707. [PMID: 37405537 DOI: 10.1007/s10237-023-01730-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Accepted: 05/23/2023] [Indexed: 07/06/2023]
Abstract
The acquisition of insights concerning the mechanobiology of aneurysmatic aortic tissues is an important field of investigation. The complete characterization of aneurysm mechanical behaviour can be carried out by biaxial experimental tests on ex vivo specimens. In literature, several works proposed bulge inflation tests as a valid method to analyse aneurysmatic tissue. Bulge test data processing requires the adoption of digital image correlation and inverse analysis approaches to estimate strain and stress distributions, respectively. In this context, however, the accuracy of inverse analysis method has not been evaluated yet. This aspect appears particularly interesting given the anisotropic behaviour of the soft tissue and the possibility to adopt different die geometries. The goal of this study is to provide an accuracy characterization of the inverse analysis applied to the bulge test technique using a numerical approach. In particular, different cases of bulge inflation were simulated in a finite element environment as a reference. To investigate the effect of tissue anisotropic degree and bulge die geometries (circular and elliptical), different input parameters were considered to obtain multiple test cases. The specimen deformed shapes, resulting from the reference finite element simulations, were then analysed through an inverse analysis approach to produce an estimation of stress distributions. The estimated stresses were, at last, compared with the values from the reference finite element simulations. The results demonstrated that the circular die geometry produces a satisfactory estimation accuracy only under certain conditions of material quasi-isotropy. On the other hand, the choice of an elliptical bulge die was proven to be more suitable for the analysis of anisotropic tissues.
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Affiliation(s)
- Emanuele Gasparotti
- BioCardioLab, Bioengineering Unit, Heart Hospital, Fondazione CNR - Regione Toscana G. Monasterio, Via Aurelia Sud, 54100, Massa, Italy
| | - Emanuele Vignali
- BioCardioLab, Bioengineering Unit, Heart Hospital, Fondazione CNR - Regione Toscana G. Monasterio, Via Aurelia Sud, 54100, Massa, Italy
| | - Stefano Quartieri
- BioCardioLab, Bioengineering Unit, Heart Hospital, Fondazione CNR - Regione Toscana G. Monasterio, Via Aurelia Sud, 54100, Massa, Italy
- Civil and Industrial Engineering Department, University of Pisa, Largo Lucio Lazzarino, 2, 56122, Pisa, Italy
| | - Roberta Lazzeri
- Civil and Industrial Engineering Department, University of Pisa, Largo Lucio Lazzarino, 2, 56122, Pisa, Italy
| | - Simona Celi
- BioCardioLab, Bioengineering Unit, Heart Hospital, Fondazione CNR - Regione Toscana G. Monasterio, Via Aurelia Sud, 54100, Massa, Italy.
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2
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Salmasi MY, Pirola S, Asimakopoulos G, Nienaber C, Athanasiou T. Risk prediction for thoracic aortic dissection: Is it time to go with the flow? J Thorac Cardiovasc Surg 2023; 166:1034-1042. [PMID: 35672182 DOI: 10.1016/j.jtcvs.2022.05.016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Revised: 04/21/2022] [Accepted: 05/03/2022] [Indexed: 11/26/2022]
Affiliation(s)
- M Yousuf Salmasi
- Department of Surgery, Imperial College London, London, United Kingdom.
| | - Selene Pirola
- BHF Centre of Research Excellence, Institute of Clinical Sciences, Imperial College London, London, United Kingdom
| | - George Asimakopoulos
- Department of Cardiology, Royal Brompton and Harefield Trust, London, United Kingdom
| | - Christoph Nienaber
- Department of Cardiology, Royal Brompton and Harefield Trust, London, United Kingdom
| | - Thanos Athanasiou
- Department of Surgery, Imperial College London, London, United Kingdom
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3
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Wang X, Carpenter HJ, Ghayesh MH, Kotousov A, Zander AC, Amabili M, Psaltis PJ. A review on the biomechanical behaviour of the aorta. J Mech Behav Biomed Mater 2023; 144:105922. [PMID: 37320894 DOI: 10.1016/j.jmbbm.2023.105922] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Revised: 05/14/2023] [Accepted: 05/20/2023] [Indexed: 06/17/2023]
Abstract
Large aortic aneurysm and acute and chronic aortic dissection are pathologies of the aorta requiring surgery. Recent advances in medical intervention have improved patient outcomes; however, a clear understanding of the mechanisms leading to aortic failure and, hence, a better understanding of failure risk, is still missing. Biomechanical analysis of the aorta could provide insights into the development and progression of aortic abnormalities, giving clinicians a powerful tool in risk stratification. The complexity of the aortic system presents significant challenges for a biomechanical study and requires various approaches to analyse the aorta. To address this, here we present a holistic review of the biomechanical studies of the aorta by categorising articles into four broad approaches, namely theoretical, in vivo, experimental and combined investigations. Experimental studies that focus on identifying mechanical properties of the aortic tissue are also included. By reviewing the literature and discussing drawbacks, limitations and future challenges in each area, we hope to present a more complete picture of the state-of-the-art of aortic biomechanics to stimulate research on critical topics. Combining experimental modalities and computational approaches could lead to more comprehensive results in risk prediction for the aortic system.
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Affiliation(s)
- Xiaochen Wang
- School of Electrical and Mechanical Engineering, The University of Adelaide, Adelaide, South Australia 5005, Australia.
| | - Harry J Carpenter
- School of Electrical and Mechanical Engineering, The University of Adelaide, Adelaide, South Australia 5005, Australia
| | - Mergen H Ghayesh
- School of Electrical and Mechanical Engineering, The University of Adelaide, Adelaide, South Australia 5005, Australia.
| | - Andrei Kotousov
- School of Electrical and Mechanical Engineering, The University of Adelaide, Adelaide, South Australia 5005, Australia
| | - Anthony C Zander
- School of Electrical and Mechanical Engineering, The University of Adelaide, Adelaide, South Australia 5005, Australia
| | - Marco Amabili
- Department of Mechanical Engineering, McGill University, Montreal H3A 0C3, Canada
| | - Peter J Psaltis
- Adelaide Medical School, The University of Adelaide, Adelaide, South Australia 5005, Australia; Department of Cardiology, Central Adelaide Local Health Network, Adelaide, South Australia 5000, Australia; Vascular Research Centre, Heart Health Theme, South Australian Health & Medical Research Institute (SAHMRI), Adelaide, South Australia 5000, Australia
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Karkhaneh Yousefi AA, Petit C, Ben Hassine A, Avril S. Stiffness sensing by smooth muscle cells: Continuum mechanics modeling of the acto-myosin role. J Mech Behav Biomed Mater 2023; 144:105990. [PMID: 37385127 DOI: 10.1016/j.jmbbm.2023.105990] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2023] [Revised: 05/30/2023] [Accepted: 06/23/2023] [Indexed: 07/01/2023]
Abstract
Aortic smooth muscle cells (SMCs) play a vital role in maintaining homeostasis in the aorta by sensing and responding to mechanical stimuli. However, the mechanisms that underlie the ability of SMCs to sense and respond to stiffness change in their environment are still partially unclear. In this study, we focus on the role of acto-myosin contractility in stiffness sensing and introduce a novel continuum mechanics approach based on the principles of thermal strains. Each stress fiber satisfies a universal stress-strain relationship driven by a Young's modulus, a contraction coefficient scaling the fictitious thermal strain, a maximum contraction stress and a softening parameter describing the sliding effects between actin and myosin filaments. To account for the inherent variability of cellular responses, large populations of SMCs are modeled with the finite-element method, each cell having a random number and a random arrangement of stress fibers. Moreover, the level of myosin activation in each stress fiber satisfies a Weibull probability density function. Model predictions are compared to traction force measurements on different SMC lineages. It is demonstrated that the model not only predicts well the effects of substrate stiffness on cellular traction, but it can also successfully approximate the statistical variations of cellular tractions induced by intercellular variability. Finally, stresses in the nuclear envelope and in the nucleus are computed with the model, showing that the variations of cytoskeletal forces induced by substrate stiffness directly induce deformations of the nucleus which can potentially alter gene expression. The predictability of the model combined to its relative simplicity are promising assets for further investigation of stiffness sensing in 3D environments. Eventually, this could contribute to decipher the effects of mechanosensitivity impairment, which are known to be at the root of aortic aneurysms.
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Affiliation(s)
| | - Claudie Petit
- Mines Saint-Etienne, Université Jean Monnet, INSERM, U1059 SAINBIOSE, 42023, Saint-Etienne, France
| | - Amira Ben Hassine
- Mines Saint-Etienne, Université Jean Monnet, INSERM, U1059 SAINBIOSE, 42023, Saint-Etienne, France
| | - Stéphane Avril
- Mines Saint-Etienne, Université Jean Monnet, INSERM, U1059 SAINBIOSE, 42023, Saint-Etienne, France.
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Wang X, Ghayesh MH, Kotousov A, Zander AC, Dawson JA, Psaltis PJ. Fluid-structure interaction study for biomechanics and risk factors in Stanford type A aortic dissection. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2023:e3736. [PMID: 37258411 DOI: 10.1002/cnm.3736] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Revised: 04/04/2023] [Accepted: 05/16/2023] [Indexed: 06/02/2023]
Abstract
Aortic dissection is a life-threatening condition with a rising prevalence in the elderly population, possibly as a consequence of the increasing population life expectancy. Untreated aortic dissection can lead to myocardial infarction, aortic branch malperfusion or occlusion, rupture, aneurysm formation and death. This study aims to assess the potential of a biomechanical model in predicting the risks of a non-dilated thoracic aorta with Stanford type A dissection. To achieve this, a fully coupled fluid-structure interaction model was developed under realistic blood flow conditions. This model of the aorta was developed by considering three-dimensional artery geometry, multiple artery layers, hyperelastic artery wall, in vivo-based physiological time-varying blood velocity profiles, and non-Newtonian blood behaviours. The results demonstrate that in a thoracic aorta with Stanford type A dissection, the wall shear stress (WSS) is significantly low in the ascending aorta and false lumen, leading to potential aortic dilation and thrombus formation. The results also reveal that the WSS is highly related to blood flow patterns. The aortic arch region near the brachiocephalic and left common carotid artery is prone to rupture, showing a good agreement with the clinical reports. The results have been translated into their potential clinical relevance by revealing the role of the stress state, WSS and flow characteristics as the main parameters affecting lesion progression, including rupture and aneurysm. The developed model can be tailored for patient-specific studies and utilised as a predictive tool to estimate aneurysm growth and initiation of wall rupture inside the human thoracic aorta.
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Affiliation(s)
- Xiaochen Wang
- School of Mechanical Engineering, University of Adelaide, Adelaide, Australia
| | - Mergen H Ghayesh
- School of Mechanical Engineering, University of Adelaide, Adelaide, Australia
| | - Andrei Kotousov
- School of Mechanical Engineering, University of Adelaide, Adelaide, Australia
| | - Anthony C Zander
- School of Mechanical Engineering, University of Adelaide, Adelaide, Australia
| | - Joseph A Dawson
- Department of Vascular & Endovascular Surgery, Royal Adelaide Hospital, Adelaide, Australia
- Trauma Surgery Unit, Royal Adelaide Hospital, Adelaide, Australia
- Adelaide Medical School, University of Adelaide, Adelaide, Australia
| | - Peter J Psaltis
- Adelaide Medical School, University of Adelaide, Adelaide, Australia
- Vascular Research Centre, Lifelong Health Theme, South Australian Health & Medical Research Institute (SAHMRI), Adelaide, Australia
- Department of Cardiology, Central Adelaide Local Health Network, Adelaide, Australia
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6
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Gomez A, Wang Z, Xuan Y, Hope MD, Saloner DA, Guccione JM, Ge L, Tseng EE. Association of diameter and wall stresses of tricuspid aortic valve ascending thoracic aortic aneurysms. J Thorac Cardiovasc Surg 2022; 164:1365-1375. [PMID: 34275618 PMCID: PMC8716675 DOI: 10.1016/j.jtcvs.2021.05.049] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/04/2020] [Revised: 05/17/2021] [Accepted: 05/21/2021] [Indexed: 12/27/2022]
Abstract
OBJECTIVE Ascending thoracic aortic aneurysms carry a risk of acute type A dissection. Elective repair guidelines are designed around size thresholds, but the 1-dimensional parameter of maximum diameter cannot predict acute events in small aneurysms. Biomechanically, dissection can occur when wall stress exceeds strength. Patient-specific ascending thoracic aortic aneurysm wall stresses may be a better predictor of dissection. Our aim was to compare wall stresses in tricuspid aortic valve-associated ascending thoracic aortic aneurysms based on diameter. METHODS Patients with tricuspid aortic valve-associated ascending thoracic aortic aneurysm and diameter 4.0 cm or greater (n = 221) were divided into groups by 0.5-cm diameter increments. Three-dimensional geometries were reconstructed from computed tomography images, and finite element models were developed taking into account prestress geometries. A fiber-embedded hyperelastic material model was applied to obtain longitudinal and circumferential wall stress distributions under systolic pressure. Median stresses with interquartile ranges were determined. The Kruskal-Wallis test was used for comparisons between size groups. RESULTS Peak longitudinal wall stresses for tricuspid aortic valve-associated ascending thoracic aortic aneurysm were 290 (265-323) kPa for size 4.0 to 4.4 cm versus 330 (296-359) kPa for 4.5 to 4.9 cm versus 339 (320-373) kPa for 5.0 to 5.4 cm versus 318 (293-351) kPa for 5.5 to 5.9 cm versus 373 (363-449) kPa for 6.0 cm or greater (P = 8.7e-8). Peak circumferential wall stresses were 460 (421-543) kPa for size 4.0 to 4.4 cm versus 503 (453-569) kPa for 4.5 to 4.9 cm versus 549 (430-588) kPa for 5.0 to 5.4 cm versus 540 (471-608) kPa for 5.5 to 5.9 cm versus 596 (506-649) kPa for 6.0 cm or greater (P = .0007). CONCLUSIONS Circumferential and longitudinal wall stresses are higher as diameter increases, but size groups had large overlap of stress ranges. Wall stress thresholds based on aneurysm wall strength may be a better predictor of patient-specific risk of dissection than diameter in small ascending thoracic aortic aneurysms.
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Affiliation(s)
- Axel Gomez
- Division of Adult Cardiothoracic Surgery, Department of Surgery, University of California San Francisco and San Francisco VA Medical Center, San Francisco, Calif
| | - Zhongjie Wang
- Division of Adult Cardiothoracic Surgery, Department of Surgery, University of California San Francisco and San Francisco VA Medical Center, San Francisco, Calif
| | - Yue Xuan
- Division of Adult Cardiothoracic Surgery, Department of Surgery, University of California San Francisco and San Francisco VA Medical Center, San Francisco, Calif
| | - Michael D Hope
- Department of Radiology & Biomedical Imaging, University of California San Francisco and San Francisco VA Medical Center, San Francisco, Calif
| | - David A Saloner
- Department of Radiology & Biomedical Imaging, University of California San Francisco and San Francisco VA Medical Center, San Francisco, Calif
| | - Julius M Guccione
- Division of Adult Cardiothoracic Surgery, Department of Surgery, University of California San Francisco and San Francisco VA Medical Center, San Francisco, Calif
| | - Liang Ge
- Division of Adult Cardiothoracic Surgery, Department of Surgery, University of California San Francisco and San Francisco VA Medical Center, San Francisco, Calif
| | - Elaine E Tseng
- Division of Adult Cardiothoracic Surgery, Department of Surgery, University of California San Francisco and San Francisco VA Medical Center, San Francisco, Calif.
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7
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Taheri RA, Razaghi R, Bahramifar A, Morshedi M, Mafi M, Karimi A. Interaction of the Blood Components with Ascending Thoracic Aortic Aneurysm Wall: Biomechanical and Fluid Analyses. Life (Basel) 2022; 12:1296. [PMID: 36143333 PMCID: PMC9503674 DOI: 10.3390/life12091296] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Revised: 08/09/2022] [Accepted: 08/19/2022] [Indexed: 01/13/2023] Open
Abstract
BACKGROUND Ascending thoracic aortic aneurysm (ATAA) is an asymptomatic localized dilation of the aorta that is prone to rupture with a high rate of mortality. While diameter is the main risk factor for rupture assessment, it has been shown that the peak wall stress from finite element (FE) simulations may contribute to refinement of clinical decisions. In FE simulations, the intraluminal boundary condition is a single-phase blood flow that interacts with the thoracic aorta (TA). However, the blood is consisted of red blood cells (RBCs), white blood cells (WBCs), and plasma that interacts with the TA wall, so it may affect the resultant stresses and strains in the TA, as well as hemodynamics of the blood. METHODS In this study, discrete elements were distributed in the TA lumen to represent the blood components and mechanically coupled using fluid-structure interaction (FSI). Healthy and aneurysmal human TA tissues were subjected to axial and circumferential tensile loadings, and the hyperelastic mechanical properties were assigned to the TA and ATAA FE models. RESULTS The ATAA showed larger tensile and shear stresses but smaller fluid velocity compared to the ATA. The blood components experienced smaller shear stress in interaction with the ATAA wall compared to TA. The computational fluid dynamics showed smaller blood velocity and wall shear stress compared to the FSI. CONCLUSIONS This study is a first proof of concept, and future investigations will aim at validating the novel methodology to derive a more reliable ATAA rupture risk assessment considering the interaction of the blood components with the TA wall.
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Affiliation(s)
- Ramezan Ali Taheri
- Nanobiotechnology Research Center, Baqiyatallah University of Medical Sciences, Tehran 1435916471, Iran
| | - Reza Razaghi
- Department of Ophthalmology and Visual Sciences, University of Alabama at Birmingham, Birmingham, AL 35233, USA
| | - Ali Bahramifar
- Trauma Research Center, Baqiyatallah University of Medical Sciences, Tehran 1435916471, Iran
| | - Mahdi Morshedi
- Department of Surgery, Trauma Research Center, Baqiyatallah University of Medical Sciences, Tehran 1435916471, Iran
| | - Majid Mafi
- Biomedical Engineering Research Center, Baqiyatallah University of Medical Sciences, Tehran 1435916471, Iran
| | - Alireza Karimi
- Department of Ophthalmology and Visual Sciences, University of Alabama at Birmingham, Birmingham, AL 35233, USA
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8
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He X, Lu J. On strain-based rupture criterion for ascending aortic aneurysm: the role of fiber waviness. Acta Biomater 2022; 149:51-59. [PMID: 35760348 DOI: 10.1016/j.actbio.2022.06.034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Revised: 05/29/2022] [Accepted: 06/20/2022] [Indexed: 11/01/2022]
Abstract
We propose a new approach for constructing strain-based rupture criterion for ascending thoracic aortic aneurysm. The rupture metric is formulated using an effective strain, which is a measure of net strain that the collagen bundles experience after fiber uncrimping. The effective strain is a function of the total strain and the waviness properties of the collagen fibers. In the present work, the waviness properties are obtained from fitting biaxial response data to constitutive models that explicitly consider the collagen waviness and fiber recruitment. Inflation test data from 10 ascending thoracic aortic aneurysm specimens are analyzed. For each specimen, tension-strain data at ∼2300 material points are garnered. The effective strain fields in the configuration immediately before rupture are computed. It is found that the hotspots of the effective strain match the rupture sites very well in all 10 samples. More importantly, the values of effective strain at the hotsopts are closely clustered around 0.1, in contrast to a much wider distribution of the total strain. The study underscores the importance of considering the fiber recruitment in formulating strain-based rupture metric, and suggests that ϵ¯≈0.1, where ϵ¯ is the effective strain metric defined in this work, can be considered as a criterion for assessing the imminent rupture risk of ascending aortic aneurysms.
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Affiliation(s)
- Xuehuan He
- Department of Mechanical Engineering, and Iowa Technology Institute The University of Iowa, Iowa City, IA 52242, USA
| | - Jia Lu
- Department of Mechanical Engineering, and Iowa Technology Institute The University of Iowa, Iowa City, IA 52242, USA.
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9
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Gomez A, Wang Z, Xuan Y, Hope MD, Saloner DA, Guccione JM, Ge L, Tseng EE. Regional wall stress differences on tricuspid aortic valve-associated ascending aortic aneurysms. Interact Cardiovasc Thorac Surg 2022; 34:1115-1123. [PMID: 34718581 PMCID: PMC10634398 DOI: 10.1093/icvts/ivab269] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2021] [Revised: 07/15/2021] [Accepted: 08/27/2021] [Indexed: 11/13/2022] Open
Abstract
OBJECTIVES Ascending thoracic aortic aneurysms (aTAAs) carry a risk of acute type A dissection. Elective repair guidelines are based on diameter, but complications often occur below diameter threshold. Biomechanically, dissection can occur when wall stress exceeds wall strength. Aneurysm wall stresses may better capture dissection risk. Our aim was to investigate patient-specific aTAA wall stresses associated with a tricuspid aortic valve (TAV) by anatomic region. METHODS Patients with aneurysm diameter ≥4.0 cm underwent computed tomography angiography. Aneurysm geometries were reconstructed and loaded to systemic pressure while taking prestress into account. Finite element analyses were conducted to obtain wall stress distributions. The 99th percentile longitudinal and circumferential stresses were determined at systole. Wall stresses between regions were compared using one-way analysis of variance with post hoc Tukey HSD for pairwise comparisons. RESULTS Peak longitudinal wall stresses on aneurysms (n = 204) were 326 [standard deviation (SD): 61.7], 246 (SD: 63.4) and 195 (SD: 38.7) kPa in sinuses of Valsalva, sinotubular junction (STJ) and ascending aorta (AscAo), respectively, with significant differences between AscAo and both sinuses (P < 0.001) and STJ (P < 0.001). Peak circumferential wall stresses were 416 (SD: 85.1), 501 (SD: 119) and 340 (SD: 57.6) kPa for sinuses, STJ and AscAo, respectively, with significant differences between AscAo and both sinuses (P < 0.001) and STJ (P < 0.001). CONCLUSIONS Circumferential and longitudinal wall stresses were greater in the aortic root than AscAo on aneurysm patients with a TAV. Aneurysm wall stress magnitudes and distribution relative to respective regional wall strength could improve understanding of aortic regions at greater risk of dissection in a particular patient.
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Affiliation(s)
- Axel Gomez
- Division of Adult Cardiothoracic Surgery, Department of Surgery, University of California San Francisco and San Francisco VA Medical Center, San Francisco, CA, USA
| | - Zhongjie Wang
- Division of Adult Cardiothoracic Surgery, Department of Surgery, University of California San Francisco and San Francisco VA Medical Center, San Francisco, CA, USA
| | - Yue Xuan
- Division of Adult Cardiothoracic Surgery, Department of Surgery, University of California San Francisco and San Francisco VA Medical Center, San Francisco, CA, USA
| | - Michael D Hope
- Department of Radiology, University of California San Francisco and San Francisco VA Medical Center, San Francisco, CA, USA
| | - David A Saloner
- Department of Radiology, University of California San Francisco and San Francisco VA Medical Center, San Francisco, CA, USA
| | - Julius M Guccione
- Division of Adult Cardiothoracic Surgery, Department of Surgery, University of California San Francisco and San Francisco VA Medical Center, San Francisco, CA, USA
| | - Liang Ge
- Division of Adult Cardiothoracic Surgery, Department of Surgery, University of California San Francisco and San Francisco VA Medical Center, San Francisco, CA, USA
| | - Elaine E Tseng
- Division of Adult Cardiothoracic Surgery, Department of Surgery, University of California San Francisco and San Francisco VA Medical Center, San Francisco, CA, USA
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Laubrie JD, Mousavi SJ, Avril S. About prestretch in homogenized constrained mixture models simulating growth and remodeling in patient-specific aortic geometries. Biomech Model Mechanobiol 2022; 21:455-469. [PMID: 35067825 PMCID: PMC8940846 DOI: 10.1007/s10237-021-01544-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Accepted: 10/01/2021] [Indexed: 11/10/2022]
Abstract
Evolution of mechanical and structural properties in the Ascending Thoracic Aorta (ATA) is the results of complex mechanobiological processes. In this work, we address some numerical challenges in order to elaborate computational models of these processes. For that, we extend the state of the art of homogenized constrained mixture (hCM) models. In these models, prestretches are assigned to the mixed constituents in order to ensure local mechanical equilibrium macroscopically, and to maintain a homeostatic level of tension in collagen fibers microscopically. Although the initial prestretches were assumed as homogeneous in idealized straight tubes, more elaborate prestretch distributions need to be considered for curved geometrical models such as patient-specific ATA. Therefore, we introduce prestretches having a three-dimensional gradient across the ATA geometry in the homeostatic reference state. We test different schemes with the objective to ensure stable growth and remodeling (G&R) simulations on patient-specific curved vessels. In these simulations, aneurysm progression is triggered by tissue changes in the constituents such as mass degradation of intramural elastin. The results show that the initial prestretches are not only critical for the stability of numerical simulations, but they also affect the G&R response. Eventually, we submit that initial conditions required for G&R simulations need to be identified regionally for ensuring realistic patient-specific predictions of aneurysm progression.
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11
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Patient-Specific Analysis of Ascending Thoracic Aortic Aneurysm with the Living Heart Human Model. Bioengineering (Basel) 2021; 8:bioengineering8110175. [PMID: 34821741 PMCID: PMC8615119 DOI: 10.3390/bioengineering8110175] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Revised: 10/26/2021] [Accepted: 11/03/2021] [Indexed: 01/11/2023] Open
Abstract
In ascending thoracic aortic aneurysms (ATAAs), aneurysm kinematics are driven by ventricular traction occurring every heartbeat, increasing the stress level of dilated aortic wall. Aortic elongation due to heart motion and aortic length are emerging as potential indicators of adverse events in ATAAs; however, simulation of ATAA that takes into account the cardiac mechanics is technically challenging. The objective of this study was to adapt the realistic Living Heart Human Model (LHHM) to the anatomy and physiology of a patient with ATAA to assess the role of cardiac motion on aortic wall stress distribution. Patient-specific segmentation and material parameter estimation were done using preoperative computed tomography angiography (CTA) and ex vivo biaxial testing of the harvested tissue collected during surgery. The lumped-parameter model of systemic circulation implemented in the LHHM was refined using clinical and echocardiographic data. The results showed that the longitudinal stress was highest in the major curvature of the aneurysm, with specific aortic quadrants having stress levels change from tensile to compressive in a transmural direction. This study revealed the key role of heart motion that stretches the aortic root and increases ATAA wall tension. The ATAA LHHM is a realistic cardiovascular platform where patient-specific information can be easily integrated to assess the aneurysm biomechanics and potentially support the clinical management of patients with ATAAs.
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Hu H, Liu Z, Chen G, Yuan D, Zheng T. Analysis of aortic wall stress and morphology in patients with type B aortic dissection. MEDICINE IN NOVEL TECHNOLOGY AND DEVICES 2021. [DOI: 10.1016/j.medntd.2021.100081] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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13
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Ghadie NM, St-Pierre JP, Labrosse MR. The Contribution of Glycosaminoglycans/Proteoglycans to Aortic Mechanics in Health and Disease: A Critical Review. IEEE Trans Biomed Eng 2021; 68:3491-3500. [PMID: 33872141 DOI: 10.1109/tbme.2021.3074053] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
While elastin and collagen have received a lot of attention as major contributors to aortic biomechanics, glycosaminoglycans (GAGs) and proteoglycans (PGs) recently emerged as additional key players whose roles must be better elucidated if one hopes to predict aortic ruptures caused by aneurysms and dissections more reliably. GAGs are highly negatively charged polysaccharide molecules that exist in the extracellular matrix (ECM) of the arterial wall. In this critical review, we summarize the current understanding of the contributions of GAGs/PGs to the biomechanics of the normal aortic wall, as well as in the case of aortic diseases such as aneurysms and dissections. Specifically, we describe the fundamental swelling behavior of GAGs/PGs and discuss their contributions to residual stresses and aortic stiffness, thereby highlighting the importance of taking these polyanionic molecules into account in mathematical and numerical models of the aorta. We suggest specific lines of investigation to further the acquisition of experimental data to complement simulations and solidify our current understanding. We underscore different potential roles of GAGs/PGs in thoracic aortic aneurysm (TAAD) and abdominal aortic aneurysm (AAA). Namely, we report findings according to which the accumulation of GAGs/PGs in TAAD causes stress concentrations which may be sufficient to initiate and propagate delamination. On the other hand, there seems to be no clear indication of a relationship between the marked reduction in GAG/PG content and the stiffening and weakening of the aortic wall in AAA.
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14
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Zuo D, Avril S, Ran C, Yang H, Mousavi SJ, Hackl K, He Y. Sensitivity analysis of non-local damage in soft biological tissues. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2021; 37:e3427. [PMID: 33301233 DOI: 10.1002/cnm.3427] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Revised: 11/27/2020] [Accepted: 12/04/2020] [Indexed: 06/12/2023]
Abstract
Computational modeling can provide insight into understanding the damage mechanisms of soft biological tissues. Our gradient-enhanced damage model presented in a previous publication has shown advantages in considering the internal length scales and in satisfying mesh independence for simulating damage, growth and remodeling processes. Performing sensitivity analyses for this model is an essential step towards applications involving uncertain patient-specific data. In this paper, a numerical analysis approach is developed. For that we integrate two existing methods, that is, the gradient-enhanced damage model and the surrogate model-based probability analysis. To increase the computational efficiency of the Monte Carlo method in uncertainty propagation for the nonlinear hyperelastic damage analysis, the surrogate model based on Legendre polynomial series is employed to replace the direct FEM solutions, and the sparse grid collocation method (SGCM) is adopted for setting the collocation points to further reduce the computational cost in training the surrogate model. The effectiveness of the proposed approach is illustrated by two numerical examples, including an application of artery dilatation mimicking to the clinical problem of balloon angioplasty.
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Affiliation(s)
- Di Zuo
- State Key Lab of Structural Analysis for Industrial Equipment, Department of Engineering Mechanics, Dalian University of Technology, Dalian, China
| | - Stéphane Avril
- Mines Saint-Étienne, University Lyon, INSERM, U1059 Sainbiose, Centre CIS, Saint-Étienne, France
| | - Chunjiang Ran
- State Key Lab of Structural Analysis for Industrial Equipment, Department of Engineering Mechanics, Dalian University of Technology, Dalian, China
| | - Haitian Yang
- State Key Lab of Structural Analysis for Industrial Equipment, Department of Engineering Mechanics, Dalian University of Technology, Dalian, China
| | - S Jamaleddin Mousavi
- Mines Saint-Étienne, University Lyon, INSERM, U1059 Sainbiose, Centre CIS, Saint-Étienne, France
| | - Klaus Hackl
- Institute of Mechanics of Materials, Ruhr-Universität Bochum, Bochum, Germany
| | - Yiqian He
- State Key Lab of Structural Analysis for Industrial Equipment, Department of Engineering Mechanics, Dalian University of Technology, Dalian, China
- Key Laboratory of Biorheological and Technology of Ministry of Education, Chongqing University, Chongqing, China
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15
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Regulation of SMC traction forces in human aortic thoracic aneurysms. Biomech Model Mechanobiol 2021; 20:717-731. [PMID: 33449277 PMCID: PMC7979631 DOI: 10.1007/s10237-020-01412-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2019] [Accepted: 12/12/2020] [Indexed: 01/03/2023]
Abstract
Smooth muscle cells (SMCs) usually express a contractile phenotype in the healthy aorta. However, aortic SMCs have the ability to undergo profound changes in phenotype in response to changes in their extracellular environment, as occurs in ascending thoracic aortic aneurysms (ATAA). Accordingly, there is a pressing need to quantify the mechanobiological effects of these changes at single cell level. To address this need, we applied Traction Force Microscopy (TFM) on 759 cells coming from three primary healthy (AoPrim) human SMC lineages and three primary aneurysmal (AnevPrim) human SMC lineages, from age and gender matched donors. We measured the basal traction forces applied by each of these cells onto compliant hydrogels of different stiffness (4, 8, 12, 25 kPa). Although the range of force generation by SMCs suggested some heterogeneity, we observed that: 1. the traction forces were significantly larger on substrates of larger stiffness; 2. traction forces in AnevPrim were significantly higher than in AoPrim cells. We modelled computationally the dynamic force generation process in SMCs using the motor-clutch model and found that it accounts well for the stiffness-dependent traction forces. The existence of larger traction forces in the AnevPrim SMCs were related to the larger size of cells in these lineages. We conclude that phenotype changes occurring in ATAA, which were previously known to reduce the expression of elongated and contractile SMCs (rendering SMCs less responsive to vasoactive agents), tend also to induce stronger SMCs. Future work aims at understanding the causes of this alteration process in aortic aneurysms.
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16
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Estimating aortic thoracic aneurysm rupture risk using tension-strain data in physiological pressure range: an in vitro study. Biomech Model Mechanobiol 2021; 20:683-699. [PMID: 33389275 DOI: 10.1007/s10237-020-01410-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Accepted: 12/02/2020] [Indexed: 12/17/2022]
Abstract
Previous studies have shown that the rupture properties of an ascending thoracic aortic aneurysm (ATAA) are strongly correlated with the pre-rupture response features. In this work, we present a two-step machine learning method to predict where the rupture is likely to occur in ATAA and what safety reserve the structure may have. The study was carried out using ATAA specimens from 15 patients who underwent surgical intervention. Through inflation test, full-field deformation data and post-rupture images were collected, from which the wall tension and surface strain distributions were computed. The tension-strain data in the pressure range of 9-18 kPa were fitted to a third-order polynomial to characterize the response properties. It is hypothesized that the region where rupture is prone to initiate is associated with a high level of tension buildup. A machine learning method is devised to predict the peak risk region. The predicted regions were found to match the actual rupture sites in 13 samples out of the total 15. In the second step, another machine learning model is utilized to predict the tissue's rupture strength in the peak risk region. Results suggest that the ATAA rupture risk can be reasonably predicted using tension-strain response in the physiological range. This may open a pathway for evaluating the ATAA rupture propensity using information of in vivo response.
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17
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Subramaniam DR, Gutmark E, Andersen N, Nielsen D, Mortensen K, Gravholt C, Backeljauw P, Gutmark-Little I. Influence of Material Model and Aortic Root Motion in Finite Element Analysis of Two Exemplary Cases of Proximal Aortic Dissection. J Biomech Eng 2021; 143:014504. [PMID: 32793953 DOI: 10.1115/1.4048084] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2020] [Indexed: 01/25/2023]
Abstract
The risk of type-A dissection is increased in subjects with connective tissue disorders and dilatation of the proximal aorta. The location and extents of vessel wall tears in these patients could be potentially missed during prospective imaging studies. The objective of this study is to estimate the distribution of systolic wall stress in two exemplary cases of proximal dissection using finite element analysis (FEA) and evaluate the sensitivity of the distribution to the choice of anisotropic material model and root motion. FEA was performed for predissection aortas, without prior knowledge of the origin and extents of vessel wall tear. The stress distribution was evaluated along the wall tear in the postdissection aortas. The stress distribution was compared for the Fung and Holzapfel models with and without root motion. For the subject with spiral dissection, peak stress coincided with the origin of the tear in the sinotubular junction. For the case with root dissection, maximum stress was obtained at the distal end of the tear. The FEA predicted tear pressure was 20% higher for the subject with root dissection as compared to the case with spiral dissection. The predicted tear pressure was higher (9-11%) for root motions up to 10 mm. The Holzapfel model predicted a tear pressure that was lower (8-15%) than the Fung model. The FEA results showed that both material response and root motion could potentially influence the predicted dissection pressure of the proximal aorta at least for conditions tested in this study.
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Affiliation(s)
| | - Ephraim Gutmark
- Department of Aerospace Engineering and Engineering Mechanics, University of Cincinnati, Cincinnati, OH 45221-0070
| | - Niels Andersen
- Department of Cardiology, Aalborg University Hospital, Aalborg 9100, Denmark
| | - Dorte Nielsen
- Department of Cardiology, Aarhus University Hospital, Aarhus 8200, Denmark
| | - Kristian Mortensen
- Cardiorespiratory Unit, Great Ormond Street Hospital for Children, London WC1N 3JH, UK
| | - Claus Gravholt
- Department of Endocrinology and Internal Medicine, Aarhus University Hospital, Aarhus 8200, Denmark
| | - Philippe Backeljauw
- Division of Endocrinology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229
| | - Iris Gutmark-Little
- Division of Endocrinology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229
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18
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Prediction of local strength of ascending thoracic aortic aneurysms. J Mech Behav Biomed Mater 2020; 115:104284. [PMID: 33348213 DOI: 10.1016/j.jmbbm.2020.104284] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2019] [Revised: 12/08/2020] [Accepted: 12/14/2020] [Indexed: 12/12/2022]
Abstract
Knowledges of both local stress and strength are needed for a reliable evaluation of the rupture risk for ascending thoracic aortic aneurysm (ATAA). In this study, machine learning is applied to predict the local strength of ATAA tissues based on tension-strain data collected through in vitro inflation tests on tissue samples. Inputs to machine learning models are tension, strain, slope, and curvature values at two points on the low strain region of the tension-strain curve. The models are trained using data from locations where the tissue ruptured, and subsequently applied to data from intact sites to predict the local rupture strength. The predicted strengths are compared with the known strength at rupture sites as well as the highest tension the tissues experienced at the intact sites. A local rupture index, which is the ratio of the end tension to the predicted rupture strength, is computed. The 'hot spots' of the rupture index are found to match the rupture sites better than those of the peak tension. The study suggests that the strength of ATAA tissue could be reliably predicted from early phase response features defined in this work.
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Vignali E, di Bartolo F, Gasparotti E, Malacarne A, Concistré G, Chiaramonti F, Murzi M, Positano V, Landini L, Celi S. Correlation between micro and macrostructural biaxial behavior of ascending thoracic aneurysm: a novel experimental technique. Med Eng Phys 2020; 86:78-85. [PMID: 33261737 DOI: 10.1016/j.medengphy.2020.10.012] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2020] [Revised: 10/01/2020] [Accepted: 10/21/2020] [Indexed: 02/08/2023]
Abstract
Mechanical properties and microstructural modifications of vessel tissues are strongly linked, as established in the state of the art of cardiovascular diseases. Techniques to obtain both mechanical and structural information are reported, but the possibility to obtain real-time microstructural and macrostructural data correlated is still lacking. An experimental approach to characterize the aortic tissue is presented. A setup integrating biaxial traction and Small Angle Light Scattering (SALS) analysis is described. The system was adopted to test ex-vivo aorta specimens from healthy and aneusymatic (aTAA) cases. A significant variation of the fiber dispersion with respect to the unloaded state was encountered during the material traction. The corresponding microstructural and mechanical data were successfully used to fit a given anisotropic constitutive model, with satisfactory R2 values (0.97±0.11 and 0.96±0.17, for aTAA and healthy population, respectively) and fiber dispersion parameters variations between the aTAA and healthy populations (0.39±0.23 and 0.15±0.10). The method integrating the biaxial/SALS technique was validated, allowing for real-time synchronization between mechanical and microstructural analysis of anisotropic biological tissues.
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Affiliation(s)
- Emanuele Vignali
- BioCardioLab, Ospedale del Cuore, Fondazione Toscana G. Monasterio, Massa, Italy; Department of Information Engineering, University of Pisa, Pisa, Italy
| | - Francesco di Bartolo
- BioCardioLab, Ospedale del Cuore, Fondazione Toscana G. Monasterio, Massa, Italy; Department of Information Engineering, University of Pisa, Pisa, Italy
| | - Emanuele Gasparotti
- BioCardioLab, Ospedale del Cuore, Fondazione Toscana G. Monasterio, Massa, Italy; Department of Information Engineering, University of Pisa, Pisa, Italy
| | | | - Giovanni Concistré
- Adult Cardiosurgery Unit, Ospedale del Cuore, Fondazione Toscana Gabriele Monasterio, Massa, Italy
| | - Francesca Chiaramonti
- Adult Cardiosurgery Unit, Ospedale del Cuore, Fondazione Toscana Gabriele Monasterio, Massa, Italy
| | - Michele Murzi
- Adult Cardiosurgery Unit, Ospedale del Cuore, Fondazione Toscana Gabriele Monasterio, Massa, Italy
| | - Vincenzo Positano
- BioCardioLab, Ospedale del Cuore, Fondazione Toscana G. Monasterio, Massa, Italy
| | - Luigi Landini
- Department of Information Engineering, University of Pisa, Pisa, Italy
| | - Simona Celi
- BioCardioLab, Ospedale del Cuore, Fondazione Toscana G. Monasterio, Massa, Italy.
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20
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Bersi MR, Acosta Santamaría VA, Marback K, Di Achille P, Phillips EH, Goergen CJ, Humphrey JD, Avril S. Multimodality Imaging-Based Characterization of Regional Material Properties in a Murine Model of Aortic Dissection. Sci Rep 2020; 10:9244. [PMID: 32514185 PMCID: PMC7280301 DOI: 10.1038/s41598-020-65624-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Accepted: 05/04/2020] [Indexed: 01/21/2023] Open
Abstract
Chronic infusion of angiotensin-II in atheroprone (ApoE-/-) mice provides a reproducible model of dissection in the suprarenal abdominal aorta, often with a false lumen and intramural thrombus that thickens the wall. Such lesions exhibit complex morphologies, with different regions characterized by localized changes in wall composition, microstructure, and properties. We sought to quantify the multiaxial mechanical properties of murine dissecting aneurysm samples by combining in vitro extension-distension data with full-field multimodality measurements of wall strain and thickness to inform an inverse material characterization using the virtual fields method. A key advance is the use of a digital volume correlation approach that allows for characterization of properties not only along and around the lesion, but also across its wall. Specifically, deformations are measured at the adventitial surface by tracking motions of a speckle pattern using a custom panoramic digital image correlation technique while deformations throughout the wall and thrombus are inferred from optical coherence tomography. These measurements are registered and combined in 3D to reconstruct the reference geometry and compute the 3D finite strain fields in response to pressurization. Results reveal dramatic regional variations in material stiffness and strain energy, which reflect local changes in constituent area fractions obtained from histology but emphasize the complexity of lesion morphology and damage within the dissected wall. This is the first point-wise biomechanical characterization of such complex, heterogeneous arterial segments. Because matrix remodeling is critical to the formation and growth of these lesions, we submit that quantification of regional material properties will increase the understanding of pathological mechanical mechanisms underlying aortic dissection.
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Affiliation(s)
- Matthew R Bersi
- Department of Biomedical Engineering, Yale University, New Haven, CT, USA
- Department of Biomedical Engineering, Vanderbilt University, Nashville, TN, USA
| | | | - Karl Marback
- Department of Biomedical Engineering, Yale University, New Haven, CT, USA
| | - Paolo Di Achille
- Department of Biomedical Engineering, Yale University, New Haven, CT, USA
| | - Evan H Phillips
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN, USA
| | - Craig J Goergen
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN, USA
| | - Jay D Humphrey
- Department of Biomedical Engineering, Yale University, New Haven, CT, USA
- Vascular Biology and Therapeutics Program, Yale School of Medicine, New Haven, CT, USA
| | - Stéphane Avril
- Mines Saint-Etienne, University of Lyon, University Jean Monnet, INSERM, Saint-Etienne, France.
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21
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Iliopoulos DC, Sokolis DP. Ascending aorta mechanics in bicuspid aortopathy: controversy or fact? Asian Cardiovasc Thorac Ann 2020; 29:592-604. [PMID: 32447961 DOI: 10.1177/0218492320928731] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Bicuspid aortic valve is the most common congenital cardiovascular defect, often associated with proximal aortic dilatation, and the ideal management strategy is debated. The inconsistency in previous and present guideline recommendations emphasizes the insufficiency of the maximal diameter as the sole criterion for prophylactic repair. Our ability to guide clinical decisions may improve through an understanding of the mechanical properties of ascending thoracic aortic aneurysms in bicuspid compared to tricuspid aortic valve patients and non-aneurysmal aortas, because dissection and rupture are aortic wall mechanical failures. Such an understanding of the mechanical properties has been attempted by several authors, and this article addresses whether there is a controversy in the accumulated knowledge. The available mechanical studies are briefly reviewed, discussing factors such as age, sex, and the region of mechanical examination that may be responsible for the lack of unanimity in the reported findings. The rationale for acquiring layer-specific properties is presented along with the main results from our recent study. No mechanical vulnerability of ascending thoracic aortic aneurysms was evidenced in bicuspid aortic valve patients, corroborating present conservative guidelines concerning the management of bicuspid aortopathy. Weakening and additional vulnerability was evidenced in aged patients and those with coexisting valve pathology, aortic root dilatation, hypertension, and hyperlipidemia. Discussion of these results from age- and sex-matched subjects, accounting for the region- and layer-specific aortic heterogeneity, in relation to intact wall results and histologic confirmation, helps to reconcile previous findings and affords a universal interpretation of ascending aorta mechanics in bicuspid aortopathy.
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Affiliation(s)
- Dimitrios C Iliopoulos
- Department of Cardiac Surgery, National and Kapodistrian University of Athens, and 4th Cardiac Surgery Department, Hygeia Hospital, Athens, Greece
| | - Dimitrios P Sokolis
- Biomechanics Laboratory, Center of Clinical, Experimental Surgery, and Translational Research, Biomedical Research Foundation of the Academy of Athens, Athens, Greece
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22
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Characterization of chemoelastic effects in arteries using digital volume correlation and optical coherence tomography. Acta Biomater 2020; 102:127-137. [PMID: 31794873 DOI: 10.1016/j.actbio.2019.11.049] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2019] [Revised: 11/25/2019] [Accepted: 11/26/2019] [Indexed: 12/13/2022]
Abstract
Understanding stress-strain relationships in arteries is important for fundamental investigations in mechanobiology. Here we demonstrate the essential role of chemoelasticity in determining the mechanical properties of arterial tissues. Stepwise stress-relaxation uniaxial tensile tests were carried out on samples of porcine thoracic aortas immersed in a hyperosmotic solution. The tissue deformations were tracked using optical coherence tomography (OCT) during the tensile tests and digital volume correlation (DVC) was used to obtain measurements of depth-resolved strains across the whole thickness of the tested aortas. The hyperosmotic solution exacerbated chemoelastic effects, and we were able to measure different manifestations of these chemoelastic effects: swelling of the media inducing a modification of its optical properties, and existence of a transverse tensile strain. For the first time ever to our best knowledge, 3D strains induced by chemoelastic effects in soft tissues were quantified thanks to the OCT-DVC method. Without doubt, chemoelasticity plays an essential role in arterial mechanobiology in vivo and future work should focus on characterizing chemoelastic effects in arterial walls under physiological and disease conditions. STATEMENT OF SIGNIFICANCE: Chemoelasticity, coupling osmotic phenomena and mechanical stresses, is essential in soft tissue mechanobiology. For the first time ever, we measure and analyze 3D strain fields induced by these chemoelastic effects thanks to the unique combination of OCT imaging and digital volume correlation.
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Korenczuk CE, Dhume RY, Liao KK, Barocas VH. Ex Vivo Mechanical Tests and Multiscale Computational Modeling Highlight the Importance of Intramural Shear Stress in Ascending Thoracic Aortic Aneurysms. J Biomech Eng 2019; 141:121010. [PMID: 31633165 PMCID: PMC7104749 DOI: 10.1115/1.4045270] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Revised: 10/17/2019] [Indexed: 11/08/2022]
Abstract
Ascending thoracic aortic aneurysms (ATAAs) are anatomically complex in terms of architecture and geometry, and both complexities contribute to unpredictability of ATAA dissection and rupture in vivo. The goal of this work was to examine the mechanism of ATAA failure using a combination of detailed mechanical tests on human tissue and a multiscale computational model. We used (1) multiple, geometrically diverse, mechanical tests to characterize tissue properties; (2) a multiscale computational model to translate those results into a broadly usable form; and (3) a model-based computer simulation of the response of an ATAA to the stresses generated by the blood pressure. Mechanical tests were performed in uniaxial extension, biaxial extension, shear lap, and peel geometries. ATAA tissue was strongest in circumferential extension and weakest in shear, presumably because of the collagen and elastin in the arterial lamellae. A multiscale, fiber-based model using different fiber properties for collagen, elastin, and interlamellar connections was specified to match all of the experimental data with one parameter set. Finally, this model was used to simulate ATAA inflation using a realistic geometry. The predicted tissue failure occurred in regions of high stress, as expected; initial failure events involved almost entirely interlamellar connections, consistent with arterial dissection-the elastic lamellae remain intact, but the connections between them fail. The failure of the interlamellar connections, paired with the weakness of the tissue under shear loading, is suggestive that shear stress within the tissue may contribute to ATAA dissection.
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Affiliation(s)
- Christopher E. Korenczuk
- Department of Biomedical Engineering, University of Minnesota,7-105 Nils Hasselmo Hall, 312 Church Street SE, Minneapolis, MN 55455e-mail:
| | - Rohit Y. Dhume
- Department of Mechanical Engineering, University of Minnesota,7-105 Nils Hasselmo Hall, 312 Church Street SE, Minneapolis, MN 55455e-mail:
| | - Kenneth K. Liao
- Department of Surgery, University of Minnesota,420 Delaware Street SE, MMC 207, Minneapolis, MN 55455e-mail:
| | - Victor H. Barocas
- Department of Biomedical Engineering, University of Minnesota,7-105 Nils Hasselmo Hall, 312 Church Street SE, Minneapolis, MN 55455e-mail:
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Sherifova S, Holzapfel GA. Biomechanics of aortic wall failure with a focus on dissection and aneurysm: A review. Acta Biomater 2019; 99:1-17. [PMID: 31419563 PMCID: PMC6851434 DOI: 10.1016/j.actbio.2019.08.017] [Citation(s) in RCA: 80] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Revised: 08/05/2019] [Accepted: 08/08/2019] [Indexed: 12/12/2022]
Abstract
Aortic dissections and aortic aneurysms are fatal events characterized by structural changes to the aortic wall. The maximum diameter criterion, typically used for aneurysm rupture risk estimations, has been challenged by more sophisticated biomechanically motivated models in the past. Although these models are very helpful for the clinicians in decision-making, they do not attempt to capture material failure. Following a short overview of the microstructure of the aorta, we analyze the failure mechanisms involved in the dissection and rupture by considering also traumatic rupture. We continue with a literature review of experimental studies relevant to quantify tissue strength. More specifically, we summarize more extensively uniaxial tensile, bulge inflation and peeling tests, and we also specify trouser, direct tension and in-plane shear tests. Finally we analyze biomechanically motivated models to predict rupture risk. Based on the findings of the reviewed studies and the rather large variations in tissue strength, we propose that an appropriate material failure criterion for aortic tissues should also reflect the microstructure in order to be effective. STATEMENT OF SIGNIFICANCE: Aortic dissections and aortic aneurysms are fatal events characterized by structural changes to the aortic wall. Despite the advances in medical, biomedical and biomechanical research, the mortality rates of aneurysms and dissections remain high. The present review article summarizes experimental studies that quantify the aortic wall strength and it discusses biomechanically motivated models to predict rupture risk. We identified contradictory observations and a large variation within and between data sets, which may be due to biological variations, different sample sizes, differences in experimental protocols, etc. Based on the findings of the reviewed literature and the rather large variations in tissue strength, it is proposed that an appropriate criterion for aortic failure should also reflect the microstructure.
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Affiliation(s)
- Selda Sherifova
- Institute of Biomechanics, Graz University of Technology, Stremayrgasse 16/2, 8010 Graz, Austria
| | - Gerhard A Holzapfel
- Institute of Biomechanics, Graz University of Technology, Stremayrgasse 16/2, 8010 Graz, Austria; Department of Structural Engineering, Norwegian Institute of Science and Technology (NTNU), 7491 Trondheim, Norway.
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25
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Cavinato C, Molimard J, Curt N, Campisi S, Orgéas L, Badel P. Does the Knowledge of the Local Thickness of Human Ascending Thoracic Aneurysm Walls Improve Their Mechanical Analysis? Front Bioeng Biotechnol 2019; 7:169. [PMID: 31380360 PMCID: PMC6646470 DOI: 10.3389/fbioe.2019.00169] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2019] [Accepted: 07/02/2019] [Indexed: 12/22/2022] Open
Abstract
Ascending thoracic aortic aneurysm (ATAA) ruptures are life threatening phenomena which occur in local weaker regions of the diseased aortic wall. As ATAAs are evolving pathologies, their growth represents a significant local remodeling and degradation of the microstructural architecture and thus their mechanical properties. To address the need for deeper study of ATAAs and their failure, it is required to analyze the mechanical behavior at the sub-millimeter scale by making use of accurate geometrical and kinematical measurements during their deformation. For this purpose, we propose a novel methodology that combined an accurate tool for thickness distribution measurement of the arterial wall, digital image correlation to assess local strain fields and bulge inflation to characterize the physiological and failure response of flat unruptured human ATAA specimens. The analysis of the heterogeneity of the local thickness and local physiological stress and strain was carried out for each investigated subject. At the subject level, our results state the presence of a non-consistent relationship between the local wall thickness and the local physiological strain field and high heterogeneity of the variables. At the inter-subject level, thicknesses were studied in relation to physiological strain and stress and load at rupture. The rupture pressure was correlated with neither the average thickness nor the lowest thickness of the specimens. Our results confirm that intrinsic material strength (hence structure) differs a lot from a subject to another and even within the same subject.
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Affiliation(s)
- Cristina Cavinato
- Mines Saint-Etienne, Centre CIS, INSERM, U 1059 Sainbiose, Univ Lyon, Univ Jean Monnet, Saint-Etienne, France
| | - Jerome Molimard
- Mines Saint-Etienne, Centre CIS, INSERM, U 1059 Sainbiose, Univ Lyon, Univ Jean Monnet, Saint-Etienne, France
| | - Nicolas Curt
- Mines Saint-Etienne, Centre CIS, INSERM, U 1059 Sainbiose, Univ Lyon, Univ Jean Monnet, Saint-Etienne, France
| | - Salvatore Campisi
- Department of CardioVascular Surgery, CHU Hôpital Nord Saint-Etienne, Saint-Etienne, France
| | - Laurent Orgéas
- UMR 5521, Univ. Grenoble Alpes, CNRS, Grenoble INP, 3SR Lab, Grenoble, France
| | - Pierre Badel
- Mines Saint-Etienne, Centre CIS, INSERM, U 1059 Sainbiose, Univ Lyon, Univ Jean Monnet, Saint-Etienne, France
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Cosentino F, Agnese V, Raffa GM, Gentile G, Bellavia D, Zingales M, Pilato M, Pasta S. On the role of material properties in ascending thoracic aortic aneurysms. Comput Biol Med 2019; 109:70-78. [DOI: 10.1016/j.compbiomed.2019.04.022] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Revised: 04/20/2019] [Accepted: 04/20/2019] [Indexed: 12/31/2022]
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27
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Cosentino F, Scardulla F, D'Acquisto L, Agnese V, Gentile G, Raffa G, Bellavia D, Pilato M, Pasta S. Computational modeling of bicuspid aortopathy: Towards personalized risk strategies. J Mol Cell Cardiol 2019; 131:122-131. [PMID: 31047985 DOI: 10.1016/j.yjmcc.2019.04.026] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/26/2019] [Revised: 04/09/2019] [Accepted: 04/26/2019] [Indexed: 11/18/2022]
Abstract
This paper describes current advances on the application of in-silico for the understanding of bicuspid aortopathy and future perspectives of this technology on routine clinical care. This includes the impact that artificial intelligence can provide to develop computer-based clinical decision support system and that wearable sensors can offer to remotely monitor high-risk bicuspid aortic valve (BAV) patients. First, we discussed the benefit of computational modeling by providing tangible examples of in-silico software products based on computational fluid-dynamic (CFD) and finite-element method (FEM) that are currently transforming the way we diagnose and treat cardiovascular diseases. Then, we presented recent findings on computational hemodynamic and structural mechanics of BAV to highlight the potentiality of patient-specific metrics (not-based on aortic size) to support the clinical-decision making process of BAV-associated aneurysms. Examples of BAV-related personalized healthcare solutions are illustrated.
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Affiliation(s)
- Federica Cosentino
- Promozione della Salute, Materno-Infantile, di Medicina Interna e Specialistica di Eccellenza "G. D'Alessandro", University of Palermo, Piazza delle Cliniche, n.2, 90128 Palermo, Italy; Fondazione Ri.MED, Via Bandiera n.11, 90133 Palermo, Italy
| | - Francesco Scardulla
- Department of Engineering, University of Palermo, Viale delle Scienze Ed.8, 90128 Palermo, Italy
| | - Leonardo D'Acquisto
- Department of Engineering, University of Palermo, Viale delle Scienze Ed.8, 90128 Palermo, Italy
| | - Valentina Agnese
- Department for the Treatment and Study of Cardiothoracic Diseases and Cardiothoracic Transplantation, IRCCS-ISMETT, Via Tricomi n.5, 90127 Palermo, Italy
| | - Giovanni Gentile
- Department for the Treatment and Study of Cardiothoracic Diseases and Cardiothoracic Transplantation, IRCCS-ISMETT, Via Tricomi n.5, 90127 Palermo, Italy
| | - Giuseppe Raffa
- Department for the Treatment and Study of Cardiothoracic Diseases and Cardiothoracic Transplantation, IRCCS-ISMETT, Via Tricomi n.5, 90127 Palermo, Italy
| | - Diego Bellavia
- Department for the Treatment and Study of Cardiothoracic Diseases and Cardiothoracic Transplantation, IRCCS-ISMETT, Via Tricomi n.5, 90127 Palermo, Italy
| | - Michele Pilato
- Department for the Treatment and Study of Cardiothoracic Diseases and Cardiothoracic Transplantation, IRCCS-ISMETT, Via Tricomi n.5, 90127 Palermo, Italy
| | - Salvatore Pasta
- Fondazione Ri.MED, Via Bandiera n.11, 90133 Palermo, Italy; Department for the Treatment and Study of Cardiothoracic Diseases and Cardiothoracic Transplantation, IRCCS-ISMETT, Via Tricomi n.5, 90127 Palermo, Italy.
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Campobasso R, Condemi F, Viallon M, Croisille P, Campisi S, Avril S. Evaluation of Peak Wall Stress in an Ascending Thoracic Aortic Aneurysm Using FSI Simulations: Effects of Aortic Stiffness and Peripheral Resistance. Cardiovasc Eng Technol 2018; 9:707-722. [DOI: 10.1007/s13239-018-00385-z] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/17/2018] [Accepted: 10/08/2018] [Indexed: 12/25/2022]
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Mendez V, Di Giuseppe M, Pasta S. Comparison of hemodynamic and structural indices of ascending thoracic aortic aneurysm as predicted by 2-way FSI, CFD rigid wall simulation and patient-specific displacement-based FEA. Comput Biol Med 2018; 100:221-229. [DOI: 10.1016/j.compbiomed.2018.07.013] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2018] [Revised: 07/17/2018] [Accepted: 07/18/2018] [Indexed: 10/28/2022]
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30
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Farzaneh S, Trabelsi O, Avril S. Inverse identification of local stiffness across ascending thoracic aortic aneurysms. Biomech Model Mechanobiol 2018; 18:137-153. [DOI: 10.1007/s10237-018-1073-0] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2018] [Accepted: 08/16/2018] [Indexed: 01/06/2023]
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31
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Luo Y, Fan Z, Baek S, Lu J. Machine learning-aided exploration of relationship between strength and elastic properties in ascending thoracic aneurysm. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2018; 34:e2977. [PMID: 29504264 DOI: 10.1002/cnm.2977] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2017] [Revised: 02/07/2018] [Accepted: 02/23/2018] [Indexed: 06/08/2023]
Abstract
Machine learning was applied to classify tension-strain curves harvested from inflation tests on ascending thoracic aneurysm samples. The curves were classified into rupture and nonrupture groups using prerupture response features. Two groups of features were used as the basis for classification. The first was the constitutive parameters fitted from the tension-strain data, and the second was geometric parameters extracted from the tension-strain curve. Based on the importance scores provided by the machine learning, implications of some features were interrogated. It was found that (1) the value of a constitutive parameter is nearly the same for all members in the rupture group and (2) the strength correlates strongly with a tension in the early phase of response as well as with the end stiffness. The study suggests that the strength, which is not available without rupturing the tissue, may be indirectly inferred from prerupture response features.
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Affiliation(s)
- Yuanming Luo
- Department of Mechanical and Industrial Engineering, The University of Iowa, Iowa City, IA 52242, USA
| | - Zhiwei Fan
- Department of Computer Sciences, University of Wisconsin-Madison, 1210 W. Dayton St, Madison, WI 53706-1613, USA
| | - Stephen Baek
- Department of Mechanical and Industrial Engineering, The University of Iowa, Iowa City, IA 52242, USA
| | - Jia Lu
- Department of Mechanical and Industrial Engineering, The University of Iowa, Iowa City, IA 52242, USA
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32
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Mousavi SJ, Farzaneh S, Avril S. Computational predictions of damage propagation preceding dissection of ascending thoracic aortic aneurysms. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2018; 34:e2944. [PMID: 29171175 DOI: 10.1002/cnm.2944] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2017] [Revised: 10/10/2017] [Accepted: 11/12/2017] [Indexed: 06/07/2023]
Abstract
Dissections of ascending thoracic aortic aneurysms (ATAAs) cause significant morbidity and mortality worldwide. They occur when a tear in the intima-media of the aorta permits the penetration of the blood and the subsequent delamination and separation of the wall in 2 layers, forming a false channel. To predict computationally the risk of tear formation, stress analyses should be performed layer-specifically and they should consider internal or residual stresses that exist in the tissue. In the present paper, we propose a novel layer-specific damage model based on the constrained mixture theory, which intrinsically takes into account these internal stresses and can predict appropriately the tear formation. The model is implemented in finite-element commercial software Abaqus coupled with user material subroutine. Its capability is tested by applying it to the simulation of different exemplary situations, going from in vitro bulge inflation experiments on aortic samples to in vivo overpressurizing of patient-specific ATAAs. The simulations reveal that damage correctly starts from the intimal layer (luminal side) and propagates across the media as a tear but never hits the adventitia. This scenario is typically the first stage of development of an acute dissection, which is predicted for pressures of about 2.5 times the diastolic pressure by the model after calibrating the parameters against experimental data performed on collected ATAA samples. Further validations on a larger cohort of patients should hopefully confirm the potential of the model in predicting patient-specific damage evolution and possible risk of dissection during aneurysm growth for clinical applications.
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Affiliation(s)
- S Jamaleddin Mousavi
- CIS-EMSE, Ecole des Mines de Saint-Étienne, F-42023 Saint-Étienne, France
- INSERM, U1059, SAINBIOSE, F-42023 Saint-Étienne, France
- Université de Lyon, F-69000 Lyon, France
| | - Solmaz Farzaneh
- CIS-EMSE, Ecole des Mines de Saint-Étienne, F-42023 Saint-Étienne, France
- INSERM, U1059, SAINBIOSE, F-42023 Saint-Étienne, France
- Université de Lyon, F-69000 Lyon, France
| | - Stéphane Avril
- CIS-EMSE, Ecole des Mines de Saint-Étienne, F-42023 Saint-Étienne, France
- INSERM, U1059, SAINBIOSE, F-42023 Saint-Étienne, France
- Université de Lyon, F-69000 Lyon, France
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33
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A non-invasive methodology for ATAA rupture risk estimation. J Biomech 2018; 66:119-126. [DOI: 10.1016/j.jbiomech.2017.11.012] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2017] [Revised: 10/13/2017] [Accepted: 11/09/2017] [Indexed: 01/05/2023]
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34
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Farotto D, Segers P, Meuris B, Vander Sloten J, Famaey N. The role of biomechanics in aortic aneurysm management: requirements, open problems and future prospects. J Mech Behav Biomed Mater 2018; 77:295-307. [DOI: 10.1016/j.jmbbm.2017.08.019] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2017] [Revised: 08/09/2017] [Accepted: 08/15/2017] [Indexed: 12/18/2022]
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35
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Witzenburg CM, Dhume RY, Shah SB, Korenczuk CE, Wagner HP, Alford PW, Barocas VH. Failure of the Porcine Ascending Aorta: Multidirectional Experiments and a Unifying Microstructural Model. J Biomech Eng 2017; 139:2588206. [PMID: 27893044 DOI: 10.1115/1.4035264] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2016] [Indexed: 01/15/2023]
Abstract
The ascending thoracic aorta is poorly understood mechanically, especially its risk of dissection. To make better predictions of dissection risk, more information about the multidimensional failure behavior of the tissue is needed, and this information must be incorporated into an appropriate theoretical/computational model. Toward the creation of such a model, uniaxial, equibiaxial, peel, and shear lap tests were performed on healthy porcine ascending aorta samples. Uniaxial and equibiaxial tests showed anisotropy with greater stiffness and strength in the circumferential direction. Shear lap tests showed catastrophic failure at shear stresses (150-200 kPa) much lower than uniaxial tests (750-2500 kPa), consistent with the low peel tension (∼60 mN/mm). A novel multiscale computational model, including both prefailure and failure mechanics of the aorta, was developed. The microstructural part of the model included contributions from a collagen-reinforced elastin sheet and interlamellar connections representing fibrillin and smooth muscle. Components were represented as nonlinear fibers that failed at a critical stretch. Multiscale simulations of the different experiments were performed, and the model, appropriately specified, agreed well with all experimental data, representing a uniquely complete structure-based description of aorta mechanics. In addition, our experiments and model demonstrate the very low strength of the aorta in radial shear, suggesting an important possible mechanism for aortic dissection.
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Affiliation(s)
- Colleen M Witzenburg
- Department of Mechanical Engineering, University of Minnesota, Minneapolis, MN 55455
| | - Rohit Y Dhume
- Department of Mechanical Engineering, University of Minnesota, Minneapolis, MN 55455
| | - Sachin B Shah
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, MN 55455
| | | | - Hallie P Wagner
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, MN 55455
| | - Patrick W Alford
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, MN 55455
| | - Victor H Barocas
- Department of Biomedical Engineering, University of Minnesota, 7-105 Nils Hasselmo Hall, 312 Church Street SE, Minneapolis, MN 55455 e-mail:
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36
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Auricchio F, Ferrara A, Lanzarone E, Morganti S, Totaro P. A Regression Method Based on Noninvasive Clinical Data to Predict the Mechanical Behavior of Ascending Aorta Aneurysmal Tissue. IEEE Trans Biomed Eng 2017; 64:2607-2617. [DOI: 10.1109/tbme.2016.2645762] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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37
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Biaxial loading of arterial tissues with 3D in situ observations of adventitia fibrous microstructure: A method coupling multi-photon confocal microscopy and bulge inflation test. J Mech Behav Biomed Mater 2017; 74:488-498. [DOI: 10.1016/j.jmbbm.2017.07.022] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2017] [Revised: 07/06/2017] [Accepted: 07/18/2017] [Indexed: 12/24/2022]
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38
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Condemi F, Campisi S, Viallon M, Troalen T, Xuexin G, Barker AJ, Markl M, Croisille P, Trabelsi O, Cavinato C, Duprey A, Avril S. Fluid- and Biomechanical Analysis of Ascending Thoracic Aorta Aneurysm with Concomitant Aortic Insufficiency. Ann Biomed Eng 2017; 45:2921-2932. [DOI: 10.1007/s10439-017-1913-6] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2017] [Accepted: 08/31/2017] [Indexed: 01/18/2023]
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39
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Behdadfar S, Navarro L, Sundnes J, Maleckar MM, Avril S. Importance of material parameters and strain energy function on the wall stresses in the left ventricle. Comput Methods Biomech Biomed Engin 2017; 20:1223-1232. [DOI: 10.1080/10255842.2017.1347160] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Affiliation(s)
- Sareh Behdadfar
- Ecole Nationale Supérieure des Mines, CIS-EMSE, Institut national de la santé et de la recherche médicale, INSERM:UMR1059, SAINBIOSE, Saint-Etienne, France
| | - Laurent Navarro
- Ecole Nationale Supérieure des Mines, CIS-EMSE, Institut national de la santé et de la recherche médicale, INSERM:UMR1059, SAINBIOSE, Saint-Etienne, France
| | - Joakim Sundnes
- Computational Cardiac Modeling Department, Simula Research Laboratory, Fornebu, Norway
| | - Molly M. Maleckar
- Computational Cardiac Modeling Department, Simula Research Laboratory, Fornebu, Norway
- Modeling at the Allen Institute for Cell Science, Allen Institute, Seattle, WA, USA
| | - Stéphane Avril
- Ecole Nationale Supérieure des Mines, CIS-EMSE, Institut national de la santé et de la recherche médicale, INSERM:UMR1059, SAINBIOSE, Saint-Etienne, France
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40
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Patient-specific stress analyses in the ascending thoracic aorta using a finite-element implementation of the constrained mixture theory. Biomech Model Mechanobiol 2017; 16:1765-1777. [DOI: 10.1007/s10237-017-0918-2] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2016] [Accepted: 05/06/2017] [Indexed: 12/18/2022]
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41
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Rausch MK, Genet M, Humphrey JD. An augmented iterative method for identifying a stress-free reference configuration in image-based biomechanical modeling. J Biomech 2017; 58:227-231. [PMID: 28549603 DOI: 10.1016/j.jbiomech.2017.04.021] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2016] [Revised: 02/22/2017] [Accepted: 04/24/2017] [Indexed: 10/19/2022]
Abstract
Continued advances in computational power and methods have enabled image-based biomechanical modeling to become an important tool in basic science, diagnostic and therapeutic medicine, and medical device design. One of the many challenges of this approach, however, is identification of a stress-free reference configuration based on in vivo images of loaded and often prestrained or residually stressed soft tissues and organs. Fortunately, iterative methods have been proposed to solve this inverse problem, among them Sellier's method. This method is particularly appealing because it is easy to implement, convergences reasonably fast, and can be coupled to nearly any finite element package. By means of several practical examples, however, we demonstrate that in its original formulation Sellier's method is not optimally fast and may not converge for problems with large deformations. Fortunately, we can also show that a simple, inexpensive augmentation of Sellier's method based on Aitken's delta-squared process can not only ensure convergence but also significantly accelerate the method.
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Affiliation(s)
- Manuel K Rausch
- Department of Biomedical Engineering, Yale University, United States; Department of Aerospace Engineering & Engineering Mechanics, University of Texas at Austin, United States.
| | - Martin Genet
- LMS, École Polytechnique, CNRS, Université Paris-Saclay, France; Inria, Université Paris-Saclay, France
| | - Jay D Humphrey
- Department of Biomedical Engineering, Yale University, United States
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42
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Balzani D, Schmidt T, Ortiz M. Method for the quantification of rupture probability in soft collagenous tissues. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2017; 33:e02781. [PMID: 26929160 DOI: 10.1002/cnm.2781] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2015] [Revised: 01/29/2016] [Accepted: 02/22/2016] [Indexed: 06/05/2023]
Abstract
A computational method is presented for the assessment of rupture probabilities in soft collagenous tissues. This may in particular be important for the quantitative analysis of medical diseases such as atherosclerotic arteries or abdominal aortic aneurysms, where an unidentified rupture has in most cases fatal consequences. The method is based on the numerical minimization and maximization of probabilities of failure, which arise from random input quantities, for example, tissue properties. Instead of assuming probability distributions for these quantities, which are typically unknown especially for soft collagenous tissues, only restricted knowledge of these distributions is taken into account. Given this limited statistical input data, the minimized/maximized probabilities represent optimal bounds on the rupture probability, which enable a quantitative estimation of potential risks of performing or not performing medical treatment. Although easily extendable to all kinds of mechanical rupture criteria, the approach presented here incorporates stretch-based and damage-based criteria. These are evaluated based on numerical simulations of loaded tissues, where continuum mechanical material formulations are considered, which capture the supra-physiological behavior of soft collagenous tissues. Numerical examples are provided demonstrating the applicability of the method in an overstretched atherosclerotic artery. Copyright © 2016 John Wiley & Sons, Ltd.
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Affiliation(s)
- D Balzani
- TU Dresden, Institute of Mechanics and Shell Structures, Dresden, 01062, Germany
- Dresden Center for Computational Material Science, Dresden, 01062, Germany
| | - T Schmidt
- TU Dresden, Institute of Mechanics and Shell Structures, Dresden, 01062, Germany
| | - M Ortiz
- Graduate Aerospace Laboratories, California Institute of Technology, Pasadena, 91125, CA, USA
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43
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Biomechanical Characterization of Ascending Aortic Aneurysms. Biomech Model Mechanobiol 2016; 16:705-720. [DOI: 10.1007/s10237-016-0848-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2016] [Accepted: 10/17/2016] [Indexed: 12/26/2022]
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44
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Biaxial rupture properties of ascending thoracic aortic aneurysms. Acta Biomater 2016; 42:273-285. [PMID: 27345137 DOI: 10.1016/j.actbio.2016.06.028] [Citation(s) in RCA: 89] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Revised: 05/11/2016] [Accepted: 06/22/2016] [Indexed: 12/22/2022]
Abstract
UNLABELLED Although hundreds of samples obtained from ascending thoracic aortic aneurysms (ATAA) of patients undergoing elective surgical repair have already been characterized biomechanically, their rupture properties were always derived from uniaxial tensile tests. Due to their bulge shape, ATAAs are stretched biaxially in vivo. In order to understand the biaxial rupture of ATAAs, our group developed a novel methodology based on bulge inflation and full-field optical measurements. The objective of the current paper is threefold. Firstly, we will review the failure properties (maximum stress, maximum stretch) obtained by bulge inflation testing on a cohort of 31 patients and compare them with failure properties obtained by uniaxial tension in a previously published study. Secondly, we will investigate the relationship between the failure properties and the age of patients, showing that patients below 55years of age display significantly higher strength. Thirdly, we will define a rupture risk based on the extensibility of the tissue and we will show that this rupture risk is strongly correlated with the physiological elastic modulus of the tissue independently of the age, ATAA diameter or the aortic valve phenotype of the patient. STATEMENT OF SIGNIFICANCE Despite their medical importance, rupture properties of ascending thoracic aortic aneurysms (ATAA) subjected to biaxial tension were inexistent in the literature. In order to address this lack, our group developed a novel methodology based on bulge inflation and full-field optical measurements. Here we report rupture properties obtained with this methodology on 31 patients. It is shown for the first time that rupture occurs when the stretch applied to ATAAs reaches the maximum extensibility of the tissue and that this maximum extensibility correlates strongly with the elastic properties. The outcome is a better detection of at-risk individuals for elective surgical repair.
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45
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Local mechanical properties of human ascending thoracic aneurysms. J Mech Behav Biomed Mater 2016; 61:235-249. [DOI: 10.1016/j.jmbbm.2016.03.025] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2015] [Revised: 02/29/2016] [Accepted: 03/09/2016] [Indexed: 11/18/2022]
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