Endovascular aneurysm repair is a new and minimally invasive repair for patients with abdominal aortic aneurysm (AAA). However, endotension is one of the post-operative compliances of endo-vascular aneurysm repair in ...Endovascular aneurysm repair is a new and minimally invasive repair for patients with abdominal aortic aneurysm (AAA). However, endotension is one of the post-operative compliances of endo-vascular aneurysm repair in abdominal aortic aneurysm. Typically, endotension is mainly a result of pressure transmitted to the aneurysm sac through endovascular implanted graft (EVG) by intermediary of the stagnant blood filled aneurysm cavity. Focusing on a representative AAA with an EVG, a fluid-structure interaction (FSI) solver has been employed to provide physical insight for evaluating the blood flow dynamics, maximum AAA-stresses and deformations. Although implanting an EVG can reduce the sac pressure, mechanical stress and wall deformation in AAAs significantly, they remain non-zero. These magnitudes depend on multi-factors including blood flow conditions such as velocity and pressure, as well as EVG and aneurysm geometries. In this study, it was found that blood flow velocity deceleration occurs on the graft due to the curvature of its neck, so greater curvature of the graft neck can contribute to vortex formation in this area and exert load on the graft wall. In the iliac bifurcation region, divaricating of the flow leads to a large net flow momentum change. It results in additional stress on the implant graft and may lead to graft migration. One of the peak wall stress points is in the neck region where the stent-graft is in contact with the aneurysm wall. This necessitates considering adequate graft fixation to withstand the stresses of blood flow through the implanted graft. Also, maximum deformation of sac wall occurs in around the large diameter of the sac, and deformation during the systole phase is higher than that during the diastole phase.展开更多
Objective: To ascertain the technique and volume of injection increasing the success rate of endoscopic VUR treatment, we develop a novel method to numerically describe the relationship between intramural ureter anato...Objective: To ascertain the technique and volume of injection increasing the success rate of endoscopic VUR treatment, we develop a novel method to numerically describe the relationship between intramural ureter anatomy, intravesical pressure, and the theoretical mound height needed for adequate treatment. Methods: The main purpose of this study is to construct a finite element simulation of intramural ureter and injected mound which aims to numerically define the relationship between indexes which have influence in VUR endoscopic treatment. Using linearization software and numerically simulation data, the relationship between effective indexes has been derived. Results: By linearization of the effective parameters of different finite element models, the relationship between effective parameters in filling phase is derived as: H (m) = ﹣0.003467 (m) + 0.7864D (m) + 0.000233. This equation depicts adequate injected mound height as a function of internal diameter and intramural length, H = f(L, D). Conclusion: Using numerical simulation, we introduced the novel formula to predict the height of injected mound in endoscopic VUR treatment. As a result of this study, in order to increasing the success rate of this treatment, the ratio of mound height to intramural ureter diameter should be approximately 78%.展开更多
文摘Endovascular aneurysm repair is a new and minimally invasive repair for patients with abdominal aortic aneurysm (AAA). However, endotension is one of the post-operative compliances of endo-vascular aneurysm repair in abdominal aortic aneurysm. Typically, endotension is mainly a result of pressure transmitted to the aneurysm sac through endovascular implanted graft (EVG) by intermediary of the stagnant blood filled aneurysm cavity. Focusing on a representative AAA with an EVG, a fluid-structure interaction (FSI) solver has been employed to provide physical insight for evaluating the blood flow dynamics, maximum AAA-stresses and deformations. Although implanting an EVG can reduce the sac pressure, mechanical stress and wall deformation in AAAs significantly, they remain non-zero. These magnitudes depend on multi-factors including blood flow conditions such as velocity and pressure, as well as EVG and aneurysm geometries. In this study, it was found that blood flow velocity deceleration occurs on the graft due to the curvature of its neck, so greater curvature of the graft neck can contribute to vortex formation in this area and exert load on the graft wall. In the iliac bifurcation region, divaricating of the flow leads to a large net flow momentum change. It results in additional stress on the implant graft and may lead to graft migration. One of the peak wall stress points is in the neck region where the stent-graft is in contact with the aneurysm wall. This necessitates considering adequate graft fixation to withstand the stresses of blood flow through the implanted graft. Also, maximum deformation of sac wall occurs in around the large diameter of the sac, and deformation during the systole phase is higher than that during the diastole phase.
文摘Objective: To ascertain the technique and volume of injection increasing the success rate of endoscopic VUR treatment, we develop a novel method to numerically describe the relationship between intramural ureter anatomy, intravesical pressure, and the theoretical mound height needed for adequate treatment. Methods: The main purpose of this study is to construct a finite element simulation of intramural ureter and injected mound which aims to numerically define the relationship between indexes which have influence in VUR endoscopic treatment. Using linearization software and numerically simulation data, the relationship between effective indexes has been derived. Results: By linearization of the effective parameters of different finite element models, the relationship between effective parameters in filling phase is derived as: H (m) = ﹣0.003467 (m) + 0.7864D (m) + 0.000233. This equation depicts adequate injected mound height as a function of internal diameter and intramural length, H = f(L, D). Conclusion: Using numerical simulation, we introduced the novel formula to predict the height of injected mound in endoscopic VUR treatment. As a result of this study, in order to increasing the success rate of this treatment, the ratio of mound height to intramural ureter diameter should be approximately 78%.
