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Valeti C, Gurusamy S, Krishnakumar K, Easwer HV, Kannath SK, Sudhir BJ, Patnaik BSV. Numerical investigation of unruptured middle cerebral artery bifurcation aneurysms: influence of aspect ratio. Comput Methods Biomech Biomed Engin 2023:1-16. [PMID: 37968912 DOI: 10.1080/10255842.2023.2279508] [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: 12/13/2022] [Accepted: 10/30/2023] [Indexed: 11/17/2023]
Abstract
An aneurysm is a disease condition, which is due to the pathological weakening of an arterial wall. These aneurysms are often found in various branch points and bifurcations of an artery in the cerebral circulation. Most aneurysms come to medical attention, either due to brain hemorrhages caused by rupture or found unruptured. To consider surgically invasive treatment modalities, clinicians need scientific methods such as, hemodynamic analysis to assess rupture risk. The arterial wall loses its structural integrity when wall shear stress (WSS) and other hemodynamic parameters exceed a certain threshold. In the present study, numerical simulations are carried out for unruptured middle cerebral artery (MCA) aneurysms. Three distinct representative sizes are chosen from a larger patient pool of 26 MCA aneurysms. Logically, these aneurysms represent three growth stages of any patient with similar anatomical structure. Simulations are performed to compare the three growth phases (with different aspect ratios) of an aneurysm and correlate their hemodynamic parameters. Simulations with patient specific boundary conditions reveal that, aneurysms with a higher aspect ratio (AR) correspond to an attendant decrease in both time-averaged wall shear stress (TAWSS) and spatial wall shear stress gradients (WSSG). Smaller MCAs were observed to have higher positive wall shear stress divergence (WSSD), exemplifying the tensile nature of arterial wall stretching. Present study identifies positive wall shear stress divergence (PWSSD) to be a potential biomarker for evaluating the growth of an aneurysm.
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Affiliation(s)
- Chanikya Valeti
- Department of Applied Mechanics and Biomedical Engineering, IIT Madras, Chennai, India
| | - Saravanan Gurusamy
- Department of Civil, Structural and Environmental Engineering, Trinity College, Dublin, Ireland
| | - K Krishnakumar
- Department of Neurosurgery, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Trivandrum, India
| | - Hariharan Venkat Easwer
- Department of Neurosurgery, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Trivandrum, India
| | - Santhosh K Kannath
- Department of Imaging Sciences and Interventional Radiology, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Trivandrum, India
| | - B J Sudhir
- Department of Applied Mechanics and Biomedical Engineering, IIT Madras, Chennai, India
- Department of Neurosurgery, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Trivandrum, India
| | - B S V Patnaik
- Department of Applied Mechanics and Biomedical Engineering, IIT Madras, Chennai, India
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Shar JA, Keswani SG, Grande-Allen KJ, Sucosky P. Significance of aortoseptal angle anomalies to left ventricular hemodynamics and subaortic stenosis: A numerical study. Comput Biol Med 2022; 146:105613. [PMID: 35751200 PMCID: PMC10570849 DOI: 10.1016/j.compbiomed.2022.105613] [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: 04/05/2022] [Revised: 05/02/2022] [Accepted: 05/10/2022] [Indexed: 11/03/2022]
Abstract
PURPOSE Discrete subaortic stenosis (DSS) is an obstructive cardiac disease caused by a membranous lesion in the left ventricular (LV) outflow tract (LVOT). Although its etiology is unknown, the higher prevalence of DSS in LVOT anatomies featuring a steep aortoseptal angle (AoSA) suggests a potential role for hemodynamics. Therefore, the objective of this study was to quantify the impact of AoSA steepening on the LV three-dimensional (3D) hemodynamic stress environment. METHODS A 3D LV model reconstructed from cardiac cine-magnetic resonance imaging was connected to four LVOT geometrical variations spanning the clinical AoSA range (115°-160°). LV hemodynamic stresses were characterized in terms of cycle-averaged pressure, temporal shear magnitude (TSM), and oscillatory shear index. The wall shear stress (WSS) topological skeleton was further analyzed by computing the scaled divergence of the WSS vector field. RESULTS AoSA steepening caused an increasingly perturbed subaortic flow marked by LVOT flow skewness and complex 3D secondary flow patterns. These disturbances generated WSS overloads (>45% increase in TSM vs. 160° model) on the inferior LVOT wall, and increased WSS contraction (>66% decrease in WSS divergence vs. 160° model) in regions prone to DSS membrane formation. CONCLUSIONS AoSA steepening generated substantial hemodynamic stress abnormalities in LVOT regions prone to DSS formation. Further studies are needed to assess the possible impact of such mechanical abnormalities on the tissue and cellular responses.
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Affiliation(s)
- Jason A Shar
- Department of Mechanical Engineering, Kennesaw State University, 840 Polytechnic Lane, Marietta, GA, 30060, USA.
| | - Sundeep G Keswani
- Division of Pediatric Surgery, Texas Children's Hospital, Department of Surgery, Baylor College of Medicine, USA.
| | | | - Philippe Sucosky
- Department of Mechanical Engineering, Kennesaw State University, 840 Polytechnic Lane, Marietta, GA, 30060, USA.
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The association between hemodynamics and wall characteristics in human intracranial aneurysms: a review. Neurosurg Rev 2021; 45:49-61. [PMID: 33913050 DOI: 10.1007/s10143-021-01554-w] [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] [Received: 02/17/2021] [Revised: 04/02/2021] [Accepted: 04/20/2021] [Indexed: 12/28/2022]
Abstract
Hemodynamics plays a key role in the natural history of intracranial aneurysms (IAs). However, studies exploring the association between aneurysmal hemodynamics and the biological and mechanical characteristics of the IA wall in humans are sparse. In this review, we survey the current body of literature, summarize the studies' methodologies and findings, and assess the degree of consensus among them. We used PubMed to perform a systematic review of studies that explored the association between hemodynamics and human IA wall features using different sources. We identified 28 publications characterizing aneurysmal flow and the IA wall: 4 using resected tissues, 17 using intraoperative images, and 7 using vessel wall magnetic resonance imaging (MRI). Based on correlation to IA tissue, higher flow conditions, such as high wall shear stress (WSS) with complex pattern and elevated pressure, were associated with degenerated walls and collagens with unphysiological orientation and faster synthesis. MRI studies strongly supported that low flow, characterized by low WSS and high blood residence time, was associated with thicker walls and post-contrast enhancement. While significant discrepancies were found among those utilized intraoperative images, they generally supported that thicker walls coexist at regions with prolonged residence time and that thinner regions are mainly exposed to higher pressure with complex WSS patterns. The current body of literature supports a theory of two general hemodynamic-biologic mechanisms for IA development. One, where low flow conditions are associated with thickening and atherosclerotic-like remodeling, and the other where high and impinging flow conditions are related to wall degeneration, thinning, and collagen remodeling.
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Mazzi V, Gallo D, Calò K, Najafi M, Khan MO, De Nisco G, Steinman DA, Morbiducci U. A Eulerian method to analyze wall shear stress fixed points and manifolds in cardiovascular flows. Biomech Model Mechanobiol 2019; 19:1403-1423. [PMID: 31865482 DOI: 10.1007/s10237-019-01278-3] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2019] [Accepted: 12/08/2019] [Indexed: 12/12/2022]
Abstract
Based upon dynamical systems theory, a fixed point of a vector field such as the wall shear stress (WSS) at the luminal surface of a vessel is a point where the vector field vanishes. Unstable/stable manifolds identify contraction/expansion regions linking fixed points. The significance of such WSS topological features lies in their strong link with "disturbed" flow features like flow stagnation, separation and reversal, deemed responsible for vascular dysfunction initiation and progression. Here, we present a Eulerian method to analyze WSS topological skeleton through the identification and classification of WSS fixed points and manifolds in complex vascular geometries. The method rests on the volume contraction theory and analyzes the WSS topological skeleton through the WSS vector field divergence and Poincar[Formula: see text] index. The method is here applied to computational hemodynamics models of carotid bifurcation and intracranial aneurysm. An in-depth analysis of the time dependence of the WSS topological skeleton along the cardiac cycle is provided, enriching the information obtained from cycle-average WSS. Among the main findings, it emerges that on the carotid bifurcation, instantaneous WSS fixed points co-localize with cycle-average WSS fixed points for a fraction of the cardiac cycle ranging from 0 to [Formula: see text]; a persistent instantaneous WSS fixed point confined on the aneurysm dome does not co-localize with the cycle-average low-WSS region. In conclusion, the here presented approach shows the potential to speed up studies on the physiological significance of WSS topological skeleton in cardiovascular flows, ultimately increasing the chance of finding mechanistic explanations to clinical observations.
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Affiliation(s)
- Valentina Mazzi
- Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129, Turin, Italy
- PolitoBIOMed Lab, Politecnico di Torino, Turin, Italy
| | - Diego Gallo
- Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129, Turin, Italy
- PolitoBIOMed Lab, Politecnico di Torino, Turin, Italy
| | - Karol Calò
- Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129, Turin, Italy
- PolitoBIOMed Lab, Politecnico di Torino, Turin, Italy
| | - Mehdi Najafi
- Biomedical Simulation Laboratory, Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, ON, Canada
| | | | - Giuseppe De Nisco
- Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129, Turin, Italy
- PolitoBIOMed Lab, Politecnico di Torino, Turin, Italy
| | - David A Steinman
- Biomedical Simulation Laboratory, Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, ON, Canada
| | - Umberto Morbiducci
- Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129, Turin, Italy.
- PolitoBIOMed Lab, Politecnico di Torino, Turin, Italy.
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Jiang P, Liu Q, Wu J, Chen X, Li M, Li Z, Yang S, Guo R, Gao B, Cao Y, Wang R, Wang S. Hemodynamic characteristics associated with thinner regions of intracranial aneurysm wall. J Clin Neurosci 2019; 67:185-190. [PMID: 31253387 DOI: 10.1016/j.jocn.2019.06.024] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2018] [Revised: 04/20/2019] [Accepted: 06/09/2019] [Indexed: 11/30/2022]
Abstract
Aneurysm wall thickness is an important determinant of aneurysm progression and intra-procedural rupture. Several previous studies have evaluated the association between hemodynamic stress and aneurysm wall thickness, but conflicting results were obtained and no consensus has been achieved. According to the intraoperative findings, twenty-eight unruptured middle cerebral artery (MCA) aneurysms presented with thin-walled regions were enrolled in our study. Patient-specific 3D aneurysm models were constructed from preoperative computed tomography angiography (CTA) data and computational fluid dynamics (CFD) analyses were performed under pulsatile-flow conditions. Thin-walled regions of aneurysm dome were recognized by two experienced reviewers based on the intraoperative microscopy findings. Hemodynamic parameters derived from CFD analysis, including normalized wall shear stress (NWSS), normalized pressure (NP), the oscillatory shear index (OSI) and relative residence time (RRT), were compared between thin-walled regions and surrounding normal-thickness areas. Of the included aneurysms, twenty-eight pairs of thin-walled and normal surrounding regions were determined. Compared with surrounding tissues, thin-walled regions of aneurysm wall tended to present with higher pressure (1.232 vs 1.043, p < 0.05) and lower wall shear stress (0.693 vs 0.868, p < 0.05). Multivariate analysis revealed that elevated NP was significantly associated with thinning of the local aneurysm wall. Higher pressure and lower WSS were characteristic hemodynamic features associated with thinner regions of the aneurysm wall, elevated NP was an independent risk factor for local aneurysm wall thinning. CFD seems to be a useful method to estimate the location of thin-walled region, which will be helpful in reducing the risk of intraoperative rupture.
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Affiliation(s)
- Pengjun Jiang
- Department of Neurosurgery, Beijing Tiantan Hospital, Capital Medical University, Beijing, People's Republic of China; China National Clinical Research Center for Neurological Diseases, Beijing, People's Republic of China; Center of Stroke, Beijing Institute for Brain Disorders, Beijing, People's Republic of China; Beijing Key Laboratory of Translational Medicine for Cerebrovascular Diseases, Beijing, People's Republic of China
| | - Qingyuan Liu
- Department of Neurosurgery, Beijing Tiantan Hospital, Capital Medical University, Beijing, People's Republic of China; China National Clinical Research Center for Neurological Diseases, Beijing, People's Republic of China; Center of Stroke, Beijing Institute for Brain Disorders, Beijing, People's Republic of China; Beijing Key Laboratory of Translational Medicine for Cerebrovascular Diseases, Beijing, People's Republic of China
| | - Jun Wu
- Department of Neurosurgery, Beijing Tiantan Hospital, Capital Medical University, Beijing, People's Republic of China; China National Clinical Research Center for Neurological Diseases, Beijing, People's Republic of China; Center of Stroke, Beijing Institute for Brain Disorders, Beijing, People's Republic of China; Beijing Key Laboratory of Translational Medicine for Cerebrovascular Diseases, Beijing, People's Republic of China
| | - Xin Chen
- Department of Neurosurgery, Beijing Tiantan Hospital, Capital Medical University, Beijing, People's Republic of China; China National Clinical Research Center for Neurological Diseases, Beijing, People's Republic of China; Center of Stroke, Beijing Institute for Brain Disorders, Beijing, People's Republic of China; Beijing Key Laboratory of Translational Medicine for Cerebrovascular Diseases, Beijing, People's Republic of China
| | - Maogui Li
- Department of Neurosurgery, Beijing Tiantan Hospital, Capital Medical University, Beijing, People's Republic of China; China National Clinical Research Center for Neurological Diseases, Beijing, People's Republic of China; Center of Stroke, Beijing Institute for Brain Disorders, Beijing, People's Republic of China; Beijing Key Laboratory of Translational Medicine for Cerebrovascular Diseases, Beijing, People's Republic of China
| | - Zhengsong Li
- Department of Neurosurgery, Beijing Tiantan Hospital, Capital Medical University, Beijing, People's Republic of China; China National Clinical Research Center for Neurological Diseases, Beijing, People's Republic of China; Center of Stroke, Beijing Institute for Brain Disorders, Beijing, People's Republic of China; Beijing Key Laboratory of Translational Medicine for Cerebrovascular Diseases, Beijing, People's Republic of China
| | - Shuzhe Yang
- Department of Neurosurgery, Beijing Tiantan Hospital, Capital Medical University, Beijing, People's Republic of China; China National Clinical Research Center for Neurological Diseases, Beijing, People's Republic of China; Center of Stroke, Beijing Institute for Brain Disorders, Beijing, People's Republic of China; Beijing Key Laboratory of Translational Medicine for Cerebrovascular Diseases, Beijing, People's Republic of China
| | - Rui Guo
- Department of Neurosurgery, Beijing Tiantan Hospital, Capital Medical University, Beijing, People's Republic of China; China National Clinical Research Center for Neurological Diseases, Beijing, People's Republic of China; Center of Stroke, Beijing Institute for Brain Disorders, Beijing, People's Republic of China; Beijing Key Laboratory of Translational Medicine for Cerebrovascular Diseases, Beijing, People's Republic of China
| | - Bin Gao
- School of Life Science and BioEngineering, Beijing University of Technology, Beijing, People's Republic of China
| | - Yong Cao
- Department of Neurosurgery, Beijing Tiantan Hospital, Capital Medical University, Beijing, People's Republic of China; China National Clinical Research Center for Neurological Diseases, Beijing, People's Republic of China; Center of Stroke, Beijing Institute for Brain Disorders, Beijing, People's Republic of China; Beijing Key Laboratory of Translational Medicine for Cerebrovascular Diseases, Beijing, People's Republic of China
| | - Rong Wang
- Department of Neurosurgery, Beijing Tiantan Hospital, Capital Medical University, Beijing, People's Republic of China; China National Clinical Research Center for Neurological Diseases, Beijing, People's Republic of China; Center of Stroke, Beijing Institute for Brain Disorders, Beijing, People's Republic of China; Beijing Key Laboratory of Translational Medicine for Cerebrovascular Diseases, Beijing, People's Republic of China
| | - Shuo Wang
- Department of Neurosurgery, Beijing Tiantan Hospital, Capital Medical University, Beijing, People's Republic of China; China National Clinical Research Center for Neurological Diseases, Beijing, People's Republic of China; Center of Stroke, Beijing Institute for Brain Disorders, Beijing, People's Republic of China; Beijing Key Laboratory of Translational Medicine for Cerebrovascular Diseases, Beijing, People's Republic of China.
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Shimano K, Serigano S, Ikeda N, Yuchi T, Shiratori S, Nagano H. Understanding of boundary conditions imposed at multiple outlets in computational haemodynamic analysis of cerebral aneurysm. ACTA ACUST UNITED AC 2019. [DOI: 10.17106/jbr.33.32] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Affiliation(s)
- Kenjiro Shimano
- Department of Mechanical Systems Engineering, Faculty of Engineering, Tokyo City University
| | - Shota Serigano
- Graduate School of Integrative Science and Engineering, Tokyo City University
| | - Naoki Ikeda
- Department of Mechanical Systems Engineering, Faculty of Engineering, Tokyo City University
| | - Tomoki Yuchi
- Department of Mechanical Systems Engineering, Faculty of Engineering, Tokyo City University
| | - Suguru Shiratori
- Department of Mechanical Systems Engineering, Faculty of Engineering, Tokyo City University
| | - Hideaki Nagano
- Department of Mechanical Systems Engineering, Faculty of Engineering, Tokyo City University
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