Aneurysms can be classified into two main types based on their shape: saccular (spherical) and fusiform (cylindrical). In order to clarify the formation of aneurysms, we analyzed and examined the relationship between ...Aneurysms can be classified into two main types based on their shape: saccular (spherical) and fusiform (cylindrical). In order to clarify the formation of aneurysms, we analyzed and examined the relationship between external force (internal pressure) and deformation (diameter change) of a spherical model using the Neo-Hookean model, which can be used for hyperelastic materials and is similar to Hooke’s law to predict the nonlinear stress-strain behavior of materials with large deformation. For a cylindrical model, we conducted an experiment using a rubber balloon. In the spherical model, the magnitude of the internal pressure Δp value is proportional to G (modulus of rigidity) and t (thickness), and inversely proportional to R (radius of the sphere). In addition, the maximum pressure Δp (max) is reached when λ (=expanded diameter/original diameter) is approximately 1.2, and the change in diameter becomes unstable (nonlinear change) thereafter. In the cylindrical model, localized expansion occurred at λ = 1.32 (λ = 1.98 when compared to the diameter at internal pressure Δp = 0) compared to the nearby uniform diameter, followed by a sudden rapid expansion (unstable expansion jump), forming a distinct bulge, and the radial and longitudinal deformations increased with increasing Δp, leading to the rupture of the balloon. Both models have a starting point where nonlinear deformation changes (rapid expansion) occur, so quantitative observation of the artery’s shape and size is important to prevent aneurysm formation.展开更多
The mechanical response of the human arterial wall under the combined loading of inflation, axial extension, and torsion is examined within the framework of the large deformation hyper-elastic theory. The probability ...The mechanical response of the human arterial wall under the combined loading of inflation, axial extension, and torsion is examined within the framework of the large deformation hyper-elastic theory. The probability of the aneurysm formation is explained with the instability theory of structure, and the probability of its rupture is explained with the strength theory of material. Taking account of the residual stress and the smooth muscle activities, a two layer thick-walled circular cylindrical tube model with fiber-reinforced composite-based incompressible anisotropic hyper-elastic materials is employed to model the mechanical behavior of the arterial wall. The deformation curves and the stress distributions of the arterial wall are given under normal and abnormal conditions. The results of the deformation and the structure instability analysis show that the model can describe the uniform inflation deformation of the arterial wall under normal conditions, as well as formation and growth of an aneurysm under abnormal conditions such as the decreased stiffness of the elastic and collagen fibers. From the analysis of the stresses and the material strength, the rupture of an aneurysm may also be described by this model if the wall stress is larger than its strength.展开更多
A key topic for aneurysmal subarachnoid hemorrhage is neuroinflammation.Neuroinflammation can predispose to aneurysm formation and rupture.Neuroinflammation can also result from the blood breakdown products after aneu...A key topic for aneurysmal subarachnoid hemorrhage is neuroinflammation.Neuroinflammation can predispose to aneurysm formation and rupture.Neuroinflammation can also result from the blood breakdown products after aneurysm rupture.Recent evidence has shown that perpetual neuroinflammation can contribute to vasospasm and hydrocephalus.Targeting neuroinflammation is a novel mechanism for preventing subsequent neurologic sequalae.In this review,we highlight the pathophysiology of aneurysm formation,the neuroinflammatory surge after rupture including the involved cytokines,and ultimately tie in the contributory clinical relevance.In the last sections,we look at the pre-clinical data and novel avenues for further discovery.This paper will be a useful resource to both the clinician and scientific investigator.展开更多
文摘Aneurysms can be classified into two main types based on their shape: saccular (spherical) and fusiform (cylindrical). In order to clarify the formation of aneurysms, we analyzed and examined the relationship between external force (internal pressure) and deformation (diameter change) of a spherical model using the Neo-Hookean model, which can be used for hyperelastic materials and is similar to Hooke’s law to predict the nonlinear stress-strain behavior of materials with large deformation. For a cylindrical model, we conducted an experiment using a rubber balloon. In the spherical model, the magnitude of the internal pressure Δp value is proportional to G (modulus of rigidity) and t (thickness), and inversely proportional to R (radius of the sphere). In addition, the maximum pressure Δp (max) is reached when λ (=expanded diameter/original diameter) is approximately 1.2, and the change in diameter becomes unstable (nonlinear change) thereafter. In the cylindrical model, localized expansion occurred at λ = 1.32 (λ = 1.98 when compared to the diameter at internal pressure Δp = 0) compared to the nearby uniform diameter, followed by a sudden rapid expansion (unstable expansion jump), forming a distinct bulge, and the radial and longitudinal deformations increased with increasing Δp, leading to the rupture of the balloon. Both models have a starting point where nonlinear deformation changes (rapid expansion) occur, so quantitative observation of the artery’s shape and size is important to prevent aneurysm formation.
基金Project supported by the National Natural Science Foundation of China (Nos.10772104 and 10872045)the Innovation Project of the Shanghai Municipal Education Commission (No.09YZ12)the Shanghai Leading Academic Discipline Project (No.S30106)
文摘The mechanical response of the human arterial wall under the combined loading of inflation, axial extension, and torsion is examined within the framework of the large deformation hyper-elastic theory. The probability of the aneurysm formation is explained with the instability theory of structure, and the probability of its rupture is explained with the strength theory of material. Taking account of the residual stress and the smooth muscle activities, a two layer thick-walled circular cylindrical tube model with fiber-reinforced composite-based incompressible anisotropic hyper-elastic materials is employed to model the mechanical behavior of the arterial wall. The deformation curves and the stress distributions of the arterial wall are given under normal and abnormal conditions. The results of the deformation and the structure instability analysis show that the model can describe the uniform inflation deformation of the arterial wall under normal conditions, as well as formation and growth of an aneurysm under abnormal conditions such as the decreased stiffness of the elastic and collagen fibers. From the analysis of the stresses and the material strength, the rupture of an aneurysm may also be described by this model if the wall stress is larger than its strength.
文摘A key topic for aneurysmal subarachnoid hemorrhage is neuroinflammation.Neuroinflammation can predispose to aneurysm formation and rupture.Neuroinflammation can also result from the blood breakdown products after aneurysm rupture.Recent evidence has shown that perpetual neuroinflammation can contribute to vasospasm and hydrocephalus.Targeting neuroinflammation is a novel mechanism for preventing subsequent neurologic sequalae.In this review,we highlight the pathophysiology of aneurysm formation,the neuroinflammatory surge after rupture including the involved cytokines,and ultimately tie in the contributory clinical relevance.In the last sections,we look at the pre-clinical data and novel avenues for further discovery.This paper will be a useful resource to both the clinician and scientific investigator.
