Moshe Brand - Academia.edu (original) (raw)
Papers by Moshe Brand
Aortic Aneurysm, 2017
Abdominal aortic aneurysms (AAAs) are a significant cause of death in the Western world. Endovasc... more Abdominal aortic aneurysms (AAAs) are a significant cause of death in the Western world. Endovascular aneurysm repair (EVAR) is becoming the prevalently used procedure to repair AAAs (versus the traditional approach of open surgery). In cases of infrarenal AAAs, there is a risk of the renal arteries being blocked by the stent graft (SG) inserted to repair the aneurysm. In these cases, two additional SGs termed"chimney" stent grafts (CSGs) are inserted into the renal arteries in parallel with the main SG to exclude this hazard. In this study, the hemodynamics of an infrarenal AAA endovascularly repaired by a system of SGs using the "chimney" technique is investigated. Two AAA models are analyzed using computational fluid dynamics (CFD, Ansys Fluent)-a healthy abdominal aorta and an abdominal aorta post"chimney" endovascular aneurysm repair (ChEVAR) with a CSG inserted into each renal artery in parallel with the aortic SG. Results indicate that CSGs induce stagnation zones downstream the renal arteries yet mild and confined overall flow and wall shear stress (WSS) modifications. The flow regime remains principally laminar. The study findings indicate the limited hemodynamic modifications of the ChEVAR procedure and thus further support its merit.
Royal Society Open Science
Endovascular aortic aneurysm repair is a minimally invasive procedure with low mortality and morb... more Endovascular aortic aneurysm repair is a minimally invasive procedure with low mortality and morbidity. Clinical studies have revealed that a displacement force (DF) can cause stent graft (SG) migration in some circumstances requiring repeated intervention. This study aims to determine the relationship between the SG curvature and the calculated DF from four patient-specific computational fluid dynamics models. The SG's curvature was defined according to the centrelines of the implanted SG's branches. The centrelines were defined as either intersecting or separated lines. The centreline curvature (CLC) metrics were calculated based on the local curvature radii and the distances from the centrelines of idealized straight branches. The average CLC value and average variation were calculated to represent the entire graft's curvature. These CLC calculations were compared, and the method that gave the best correlation to the calculated DF was found. The optimal correlation is...
Main cause of restenosis after balloon angioplasty is due to the stresses generated in the artery... more Main cause of restenosis after balloon angioplasty is due to the stresses generated in the artery as well as from the stent artery interaction. Understanding the factors that are involved in this interaction and the ability to evaluate the stresses that are formed in the artery, could help to lessen the number of failures. The goal of the present study is to develop computationally efficient analytical model for estimating the potential damage factor as the contact stresses, and to investigate their influence upon stent design, artery and plaque parameters. The artery was stipulated to be thick walled cylinder and its stress-strain state was determined from analytic solution of Lame problem. An analytic model based on the analysis of the beams deformation in the framework EulerBernoulli assumptions was formulated for the stent. The radial pressure, which is exerted on the inner surface of the artery, is assumed to be an average of contact stresses applied by the stent and the blood ...
In recent years, more aortic aneurysm repairs are performed endovascularly using stent grafts (SG... more In recent years, more aortic aneurysm repairs are performed endovascularly using stent grafts (SGs). In this study, we analyze the hemodynamics in an aneurysmatic abdominal aorta (AAA) endovascularly repaired by a stent graft (SG) system using the chimney technique. Computational fluid dynamics (CFD) is employed to study models of a healthy aorta versus an aorta post 'chimney' endovascular aneurysm repair (ChEVAR) using chimney stent grafts (CSG). Results demonstrate that the presence of the CSGs results in stagnation regions and wall shear stress (WSS) modifications, yet the flow regime remains laminar.
Abstract—The human arm may be considered to be a redundant mechanism given a pointing task. As a ... more Abstract—The human arm may be considered to be a redundant mechanism given a pointing task. As a result, multiple arm configurations can be used to complete a pointing task in which the tip of the index finger is brought to a preselected point in space. A kinematic model of the human arm with four degrees of freedom (DOF) and the synthesis of two criteria were developed as an analytical tool for studying position tasks. The two criteria were: (1) minimizing angular joint displacement (Minimal Angular Displacement (MAD)) and (2) averaging limits of the shoulder joint range (Joint Range Availability (JRA)). Joint angles predicted by a weighted model synthesizing the MAD and JRA models was linearly correlated (slope=0.97; r2=0.81) with experimental data compared to individual criteria (MAD slope=0.76; r2=0.67 or JRA slope=1; r2=0.56). The partial contributions to the synthesized criterion were 70 % MAD and 30 % JRA. Solving the inverse kinematics problem of articulated redundant serial...
IFMBE Proceedings, 2009
Main cause of restenosis after balloon angioplasty is due to the stresses generated in the artery... more Main cause of restenosis after balloon angioplasty is due to the stresses generated in the artery as well as from the stent artery interaction. Understanding the factors that are involved in this interaction, and the ability to evaluate the stresses that are formed in the artery, could help to lessen the number of failures. The goal of the present study is to develop computationally efficient numerical models for estimating the Damage Factor (DF) as the contact stresses, and to investigate their influence upon stent design, artery and plaque parameters. At first the artery was taken as a hollow cylinder with homogenous, linear elastic properties of the material. Later, the artery was taken as a two dissimilar layers model, with non-linear hyper-elastic properties. The variation in the Damage Factor value as a function of the mismatch between stent's and artery's diameters is nearly linear, and as much as the diameter of the artery increases, the Damage Factor for the same mismatch decreases. For arteries with 75% blocking and mismatch of 1mm, the Damage Factor is 3.8.
Proceedings of The 9th EUROSIM Congress on Modelling and Simulation, EUROSIM 2016, The 57th SIMS Conference on Simulation and Modelling SIMS 2016, Dec 19, 2018
Aortic aneurysms are a main death cause in the elderly population throughout the western world. I... more Aortic aneurysms are a main death cause in the elderly population throughout the western world. In recent years, more aneurysm repairs are performed endovascularly using stent grafts (SGs) inserted into the aneurysm site through the arterial system (minimally invasive). In this study, we analyze the hemodynamics in an aneurysmatic abdominal aorta (AAA) endovascularly repaired by a stent graft (SG) system using the chimney technique. Computational fluid dynamics (CFD) is employed to study models of a healthy aorta versus an aorta post 'chimney' endovascular aneurysm repair (ChEVAR) using chimney stent grafts (CSG) inserted into each renal artery in parallel to the aortic SG. Results demonstrate that the presence of the CSGs results in stagnation regions and wall shear stress (WSS) modifications, yet the flow regime remains laminar. Thus, indicating the spatially contained effects of the ChEVAR technique and further supporting its merit.
Journal of Physical Therapy Science, 2017
This study examined whether the interval at the target angle during knee joint position sense (JP... more This study examined whether the interval at the target angle during knee joint position sense (JPS) affected reposition accuracy, and evaluated the consequence of this factor on test-retest reliability. [Subjects and Methods] Twenty healthy subjects participated in this study. Reposition ability was measured after the knee was placed at a target angle (ranging from 40° to 60°) for intervals of 3, 6, 9, and 12 seconds, in randomized order. Two trials were performed for each condition. The measurement was repeated after a week. The absolute error (AE) of each trial and average AE under each condition within the two measures were used for data analysis. [Results] No significant difference was found in comparing the AE or the average AE during all trials and between the two measures. Fair-to-good reliability was found for the AE results of all trials under the conditions of 3, 6, and 12 seconds. Poor reliability was found with time interval of 9 seconds. [Conclusion] The length of time needed to memorize the target angle during knee JPS test might affect test reliability. Practitioners can use this information when collecting JPS data.
2015 IEEE European Modelling Symposium (EMS), 2015
The Superficial Femoral Artery (SFA) is the longest section of the femoropopliteal artery and can... more The Superficial Femoral Artery (SFA) is the longest section of the femoropopliteal artery and can reach a length of 28-32 cm. Multiple stenoses can occur along its length. In such cases, two or three overlapping stents are inserted into the artery. Stent overlapping significantly increases the risk of stent fracture. Following restenosis, the procedure can lead to intermittent claudication, limb ischemia and in some cases eventually amputation. The study motivation is to evaluate the outcomes of deploying overlapping stents in terms of stresses exerted on the artery and implants and establish the fact that overlapping stents must not be designed as solitary stents. This study evaluates the stresses overlapping stents exert on the artery and on each other using a numerical (finite element) model. The model formulated comprises the stents and a two layers artery, each layer presenting hyper-elastic mechanical material properties. Results demonstrate significant increase in radial and circumferential stresses exerted on the artery at regions of overlapping stents compared with those of single stents (~50%). With similar results relating to the implant stresses. Therefore, procedures involving overlapping stents must employ uniquely designed implants of axially variable radial stiffness, not as performed today.
2015 37th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC), 2015
This paper presents a numerical analysis of the hemodynamics in an abdominal aorta (AA) with an a... more This paper presents a numerical analysis of the hemodynamics in an abdominal aorta (AA) with an aneurysm repaired by a stent graft (SG) system using the chimney technique. Computational fluid dynamics (CFD) simulations were conducted in a model of an AA repaired with a chimney stent graft (CSG) inserted into a renal artery parallel to an aortic SG and a model of a healthy AA. Comparing the simulation results of these two cases suggests that the presence of the CSG in the AA causes changes in average wall shear stress (WSS), potentially damaging recirculation zones, and additional changes in flow patterns.
This is a PDF file of an unedited manuscript that has been accepted for publication. As a service... more This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting galley proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
The presented study is focused on the hemodynamics aspects of thoracic aortic aneurysm and approa... more The presented study is focused on the hemodynamics aspects of thoracic aortic aneurysm and approaches for restoring hemodynamics in the aortic arch. The study includes numerical investigation of the aortic arch hemodynamics of a healthy aorta, aorta with aneurysm, and of two endovascular repairing procedures. The first endovascular repair approach is the total aortic arch hybrid debranching. The second implantation uses chimney graft technique. The analysis includes the fluid dynamics in the aorta and branching arteries under time-dependent physiological conditions. The results show the effect of aneurysm on blood flow in the descending aorta and in aortic arch side branches. In the aneurysmatic case, the aneurysm provokes a highly disturbed flow and large recirculation regions, especially during diastole. Out of the two endovascular techniques, the hybrid procedure was found preferred from hemodynamics point of view, with less disturbed and recirculating regions. Although the chimn...
Arteriovenous fistulae (AVF) serve as vascular access for hemodialysis. Failure of AVF often occu... more Arteriovenous fistulae (AVF) serve as vascular access for hemodialysis. Failure of AVF often occurs due to stenosis. A previous numerical study, employing pulsatile CFD with an idealized geometry (IG) model, showed a correlation between local flow disturbance and typical sites of stenosis in radiocephalic AVF, using the relative residence time (RRT) index. However, the employment of IG gives rise to the question whether or not these findings hold true for more general and patient-specific geometries. Therefore, in the current work five different AVF geometries were modeled, of which four are IG with different anastomosis angles, and the fifth involves three geometric irregularities. The results of this work show that variations in the anastomosis angle have some effect on the span and distribution of the RRT field, but the correlation between high RRT zones and typical stenosis sites is maintained. In contrast, geometric irregularities have a more significant impact on the RRT value...
Computers in biology and medicine, 2014
Restenosis is strongly attributed to stresses caused by stent-artery interactions generated in th... more Restenosis is strongly attributed to stresses caused by stent-artery interactions generated in the artery after balloon angioplasty. Numerical methods are often used to examine the stent-artery mechanical interactions. To overcome the extensive computational requirements demanded by these simulations, simplifications are needed. We introduce simplified models to calculate the mechanical interactions between net-structured stents and arteries, and discuss their validity and implications. 2D simplified numerical models are suggested, which allow cost effective assessment of arterial stresses and the potential damage factor (DF). In these models, several contact problems were solved for arteries with hyper elastic mechanical properties. Stresses were calculated for a large range of cases and for different numerical model types. The effects of model simplifications, oversizing mismatch and stenosis rate and length and symmetry on the resulting stresses were analyzed. Results obtained fr...
Volume 2: Automotive Systems; Bioengineering and Biomedical Technology; Computational Mechanics; Controls; Dynamical Systems, 2008
Main cause of restenosis after balloon angioplasty is due to the stresses generated in the artery... more Main cause of restenosis after balloon angioplasty is due to the stresses generated in the artery as well as from the stent artery interaction. Understanding the factors that are involved in this interaction and the ability to evaluate the stresses that are formed in the artery, could help to lessen the number of failures. The goal of the present study is to develop computationally efficient analytical model for estimating the potential damage factor as the contact stresses, and to investigate their influence upon stent design, artery and plaque parameters. The artery was stipulated to be thick walled cylinder and its stress-strain state was determined from analytic solution of Lame problem. An analytic model based on the analysis of the beams deformation in the framework Euler-Bernoulli assumptions was formulated for the stent. The radial pressure, which is exerted on the inner surface of the artery, is assumed to be an average of contact stresses applied by the stent and the blood...
Aortic Aneurysm, 2017
Abdominal aortic aneurysms (AAAs) are a significant cause of death in the Western world. Endovasc... more Abdominal aortic aneurysms (AAAs) are a significant cause of death in the Western world. Endovascular aneurysm repair (EVAR) is becoming the prevalently used procedure to repair AAAs (versus the traditional approach of open surgery). In cases of infrarenal AAAs, there is a risk of the renal arteries being blocked by the stent graft (SG) inserted to repair the aneurysm. In these cases, two additional SGs termed"chimney" stent grafts (CSGs) are inserted into the renal arteries in parallel with the main SG to exclude this hazard. In this study, the hemodynamics of an infrarenal AAA endovascularly repaired by a system of SGs using the "chimney" technique is investigated. Two AAA models are analyzed using computational fluid dynamics (CFD, Ansys Fluent)-a healthy abdominal aorta and an abdominal aorta post"chimney" endovascular aneurysm repair (ChEVAR) with a CSG inserted into each renal artery in parallel with the aortic SG. Results indicate that CSGs induce stagnation zones downstream the renal arteries yet mild and confined overall flow and wall shear stress (WSS) modifications. The flow regime remains principally laminar. The study findings indicate the limited hemodynamic modifications of the ChEVAR procedure and thus further support its merit.
Royal Society Open Science
Endovascular aortic aneurysm repair is a minimally invasive procedure with low mortality and morb... more Endovascular aortic aneurysm repair is a minimally invasive procedure with low mortality and morbidity. Clinical studies have revealed that a displacement force (DF) can cause stent graft (SG) migration in some circumstances requiring repeated intervention. This study aims to determine the relationship between the SG curvature and the calculated DF from four patient-specific computational fluid dynamics models. The SG's curvature was defined according to the centrelines of the implanted SG's branches. The centrelines were defined as either intersecting or separated lines. The centreline curvature (CLC) metrics were calculated based on the local curvature radii and the distances from the centrelines of idealized straight branches. The average CLC value and average variation were calculated to represent the entire graft's curvature. These CLC calculations were compared, and the method that gave the best correlation to the calculated DF was found. The optimal correlation is...
Main cause of restenosis after balloon angioplasty is due to the stresses generated in the artery... more Main cause of restenosis after balloon angioplasty is due to the stresses generated in the artery as well as from the stent artery interaction. Understanding the factors that are involved in this interaction and the ability to evaluate the stresses that are formed in the artery, could help to lessen the number of failures. The goal of the present study is to develop computationally efficient analytical model for estimating the potential damage factor as the contact stresses, and to investigate their influence upon stent design, artery and plaque parameters. The artery was stipulated to be thick walled cylinder and its stress-strain state was determined from analytic solution of Lame problem. An analytic model based on the analysis of the beams deformation in the framework EulerBernoulli assumptions was formulated for the stent. The radial pressure, which is exerted on the inner surface of the artery, is assumed to be an average of contact stresses applied by the stent and the blood ...
In recent years, more aortic aneurysm repairs are performed endovascularly using stent grafts (SG... more In recent years, more aortic aneurysm repairs are performed endovascularly using stent grafts (SGs). In this study, we analyze the hemodynamics in an aneurysmatic abdominal aorta (AAA) endovascularly repaired by a stent graft (SG) system using the chimney technique. Computational fluid dynamics (CFD) is employed to study models of a healthy aorta versus an aorta post 'chimney' endovascular aneurysm repair (ChEVAR) using chimney stent grafts (CSG). Results demonstrate that the presence of the CSGs results in stagnation regions and wall shear stress (WSS) modifications, yet the flow regime remains laminar.
Abstract—The human arm may be considered to be a redundant mechanism given a pointing task. As a ... more Abstract—The human arm may be considered to be a redundant mechanism given a pointing task. As a result, multiple arm configurations can be used to complete a pointing task in which the tip of the index finger is brought to a preselected point in space. A kinematic model of the human arm with four degrees of freedom (DOF) and the synthesis of two criteria were developed as an analytical tool for studying position tasks. The two criteria were: (1) minimizing angular joint displacement (Minimal Angular Displacement (MAD)) and (2) averaging limits of the shoulder joint range (Joint Range Availability (JRA)). Joint angles predicted by a weighted model synthesizing the MAD and JRA models was linearly correlated (slope=0.97; r2=0.81) with experimental data compared to individual criteria (MAD slope=0.76; r2=0.67 or JRA slope=1; r2=0.56). The partial contributions to the synthesized criterion were 70 % MAD and 30 % JRA. Solving the inverse kinematics problem of articulated redundant serial...
IFMBE Proceedings, 2009
Main cause of restenosis after balloon angioplasty is due to the stresses generated in the artery... more Main cause of restenosis after balloon angioplasty is due to the stresses generated in the artery as well as from the stent artery interaction. Understanding the factors that are involved in this interaction, and the ability to evaluate the stresses that are formed in the artery, could help to lessen the number of failures. The goal of the present study is to develop computationally efficient numerical models for estimating the Damage Factor (DF) as the contact stresses, and to investigate their influence upon stent design, artery and plaque parameters. At first the artery was taken as a hollow cylinder with homogenous, linear elastic properties of the material. Later, the artery was taken as a two dissimilar layers model, with non-linear hyper-elastic properties. The variation in the Damage Factor value as a function of the mismatch between stent's and artery's diameters is nearly linear, and as much as the diameter of the artery increases, the Damage Factor for the same mismatch decreases. For arteries with 75% blocking and mismatch of 1mm, the Damage Factor is 3.8.
Proceedings of The 9th EUROSIM Congress on Modelling and Simulation, EUROSIM 2016, The 57th SIMS Conference on Simulation and Modelling SIMS 2016, Dec 19, 2018
Aortic aneurysms are a main death cause in the elderly population throughout the western world. I... more Aortic aneurysms are a main death cause in the elderly population throughout the western world. In recent years, more aneurysm repairs are performed endovascularly using stent grafts (SGs) inserted into the aneurysm site through the arterial system (minimally invasive). In this study, we analyze the hemodynamics in an aneurysmatic abdominal aorta (AAA) endovascularly repaired by a stent graft (SG) system using the chimney technique. Computational fluid dynamics (CFD) is employed to study models of a healthy aorta versus an aorta post 'chimney' endovascular aneurysm repair (ChEVAR) using chimney stent grafts (CSG) inserted into each renal artery in parallel to the aortic SG. Results demonstrate that the presence of the CSGs results in stagnation regions and wall shear stress (WSS) modifications, yet the flow regime remains laminar. Thus, indicating the spatially contained effects of the ChEVAR technique and further supporting its merit.
Journal of Physical Therapy Science, 2017
This study examined whether the interval at the target angle during knee joint position sense (JP... more This study examined whether the interval at the target angle during knee joint position sense (JPS) affected reposition accuracy, and evaluated the consequence of this factor on test-retest reliability. [Subjects and Methods] Twenty healthy subjects participated in this study. Reposition ability was measured after the knee was placed at a target angle (ranging from 40° to 60°) for intervals of 3, 6, 9, and 12 seconds, in randomized order. Two trials were performed for each condition. The measurement was repeated after a week. The absolute error (AE) of each trial and average AE under each condition within the two measures were used for data analysis. [Results] No significant difference was found in comparing the AE or the average AE during all trials and between the two measures. Fair-to-good reliability was found for the AE results of all trials under the conditions of 3, 6, and 12 seconds. Poor reliability was found with time interval of 9 seconds. [Conclusion] The length of time needed to memorize the target angle during knee JPS test might affect test reliability. Practitioners can use this information when collecting JPS data.
2015 IEEE European Modelling Symposium (EMS), 2015
The Superficial Femoral Artery (SFA) is the longest section of the femoropopliteal artery and can... more The Superficial Femoral Artery (SFA) is the longest section of the femoropopliteal artery and can reach a length of 28-32 cm. Multiple stenoses can occur along its length. In such cases, two or three overlapping stents are inserted into the artery. Stent overlapping significantly increases the risk of stent fracture. Following restenosis, the procedure can lead to intermittent claudication, limb ischemia and in some cases eventually amputation. The study motivation is to evaluate the outcomes of deploying overlapping stents in terms of stresses exerted on the artery and implants and establish the fact that overlapping stents must not be designed as solitary stents. This study evaluates the stresses overlapping stents exert on the artery and on each other using a numerical (finite element) model. The model formulated comprises the stents and a two layers artery, each layer presenting hyper-elastic mechanical material properties. Results demonstrate significant increase in radial and circumferential stresses exerted on the artery at regions of overlapping stents compared with those of single stents (~50%). With similar results relating to the implant stresses. Therefore, procedures involving overlapping stents must employ uniquely designed implants of axially variable radial stiffness, not as performed today.
2015 37th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC), 2015
This paper presents a numerical analysis of the hemodynamics in an abdominal aorta (AA) with an a... more This paper presents a numerical analysis of the hemodynamics in an abdominal aorta (AA) with an aneurysm repaired by a stent graft (SG) system using the chimney technique. Computational fluid dynamics (CFD) simulations were conducted in a model of an AA repaired with a chimney stent graft (CSG) inserted into a renal artery parallel to an aortic SG and a model of a healthy AA. Comparing the simulation results of these two cases suggests that the presence of the CSG in the AA causes changes in average wall shear stress (WSS), potentially damaging recirculation zones, and additional changes in flow patterns.
This is a PDF file of an unedited manuscript that has been accepted for publication. As a service... more This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting galley proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
The presented study is focused on the hemodynamics aspects of thoracic aortic aneurysm and approa... more The presented study is focused on the hemodynamics aspects of thoracic aortic aneurysm and approaches for restoring hemodynamics in the aortic arch. The study includes numerical investigation of the aortic arch hemodynamics of a healthy aorta, aorta with aneurysm, and of two endovascular repairing procedures. The first endovascular repair approach is the total aortic arch hybrid debranching. The second implantation uses chimney graft technique. The analysis includes the fluid dynamics in the aorta and branching arteries under time-dependent physiological conditions. The results show the effect of aneurysm on blood flow in the descending aorta and in aortic arch side branches. In the aneurysmatic case, the aneurysm provokes a highly disturbed flow and large recirculation regions, especially during diastole. Out of the two endovascular techniques, the hybrid procedure was found preferred from hemodynamics point of view, with less disturbed and recirculating regions. Although the chimn...
Arteriovenous fistulae (AVF) serve as vascular access for hemodialysis. Failure of AVF often occu... more Arteriovenous fistulae (AVF) serve as vascular access for hemodialysis. Failure of AVF often occurs due to stenosis. A previous numerical study, employing pulsatile CFD with an idealized geometry (IG) model, showed a correlation between local flow disturbance and typical sites of stenosis in radiocephalic AVF, using the relative residence time (RRT) index. However, the employment of IG gives rise to the question whether or not these findings hold true for more general and patient-specific geometries. Therefore, in the current work five different AVF geometries were modeled, of which four are IG with different anastomosis angles, and the fifth involves three geometric irregularities. The results of this work show that variations in the anastomosis angle have some effect on the span and distribution of the RRT field, but the correlation between high RRT zones and typical stenosis sites is maintained. In contrast, geometric irregularities have a more significant impact on the RRT value...
Computers in biology and medicine, 2014
Restenosis is strongly attributed to stresses caused by stent-artery interactions generated in th... more Restenosis is strongly attributed to stresses caused by stent-artery interactions generated in the artery after balloon angioplasty. Numerical methods are often used to examine the stent-artery mechanical interactions. To overcome the extensive computational requirements demanded by these simulations, simplifications are needed. We introduce simplified models to calculate the mechanical interactions between net-structured stents and arteries, and discuss their validity and implications. 2D simplified numerical models are suggested, which allow cost effective assessment of arterial stresses and the potential damage factor (DF). In these models, several contact problems were solved for arteries with hyper elastic mechanical properties. Stresses were calculated for a large range of cases and for different numerical model types. The effects of model simplifications, oversizing mismatch and stenosis rate and length and symmetry on the resulting stresses were analyzed. Results obtained fr...
Volume 2: Automotive Systems; Bioengineering and Biomedical Technology; Computational Mechanics; Controls; Dynamical Systems, 2008
Main cause of restenosis after balloon angioplasty is due to the stresses generated in the artery... more Main cause of restenosis after balloon angioplasty is due to the stresses generated in the artery as well as from the stent artery interaction. Understanding the factors that are involved in this interaction and the ability to evaluate the stresses that are formed in the artery, could help to lessen the number of failures. The goal of the present study is to develop computationally efficient analytical model for estimating the potential damage factor as the contact stresses, and to investigate their influence upon stent design, artery and plaque parameters. The artery was stipulated to be thick walled cylinder and its stress-strain state was determined from analytic solution of Lame problem. An analytic model based on the analysis of the beams deformation in the framework Euler-Bernoulli assumptions was formulated for the stent. The radial pressure, which is exerted on the inner surface of the artery, is assumed to be an average of contact stresses applied by the stent and the blood...