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
Peripheral artery disease(PAD)results from the buildup of atherosclerotic plaque in the arterial wall,can progress to severe ischemia and lead to tissue necrosis and limb amputation.We evaluated a means of assessing P...Peripheral artery disease(PAD)results from the buildup of atherosclerotic plaque in the arterial wall,can progress to severe ischemia and lead to tissue necrosis and limb amputation.We evaluated a means of assessing PAD mechanics ex vivo using ten human peripheral arteries with PAD.Pressure-inflation testing was performed at six physiological pressure intervals ranging from 10 to 200 mmHg.These vessels were imaged with IVUS-VH to determine plaque composition and change in vessel structure with pressure.Statistical analysis was performed to determine which plaque structures and distributions of these structures had the greatest influence on wall deformation.We found that fibrous plaque,necrotic core,and calcification had a statistically significant effect on all variables(p<0.05).The presence of large concentrations of fibrous plaque was linked to reduced vessel compliance and ellipticity,which could lead to stent fractures and restenosis.For the plaque distribution we found that clustered necrotic core increased overall compliance while clustered calcification decreased overall compliance.The effect of plaque distribution on vessel wall deformation must be considered equally important to plaque concentration.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This work was funded by NIH grant R01EB018965.Human subjects research was conducted with Mayo Clinic Institutional Review Board approval(IRB 14-009261).
文摘Peripheral artery disease(PAD)results from the buildup of atherosclerotic plaque in the arterial wall,can progress to severe ischemia and lead to tissue necrosis and limb amputation.We evaluated a means of assessing PAD mechanics ex vivo using ten human peripheral arteries with PAD.Pressure-inflation testing was performed at six physiological pressure intervals ranging from 10 to 200 mmHg.These vessels were imaged with IVUS-VH to determine plaque composition and change in vessel structure with pressure.Statistical analysis was performed to determine which plaque structures and distributions of these structures had the greatest influence on wall deformation.We found that fibrous plaque,necrotic core,and calcification had a statistically significant effect on all variables(p<0.05).The presence of large concentrations of fibrous plaque was linked to reduced vessel compliance and ellipticity,which could lead to stent fractures and restenosis.For the plaque distribution we found that clustered necrotic core increased overall compliance while clustered calcification decreased overall compliance.The effect of plaque distribution on vessel wall deformation must be considered equally important to plaque concentration.
