We present numerical simulations of blood flow through a brain vascular aneurysm with an artificial stent using Smoothed Particle Hydrodynamics (SPH). The aim of this work is to analyze how the flow into an aneurysm c...We present numerical simulations of blood flow through a brain vascular aneurysm with an artificial stent using Smoothed Particle Hydrodynamics (SPH). The aim of this work is to analyze how the flow into an aneurysm changes using different stent configurations. The initial conditions for the simulations were constructed from angiographic images of a real patient with an aneurysm. The wall shear stresses, pressure and highest velocity within the artery, and other particular quantities are calculated which are of medical specific interest. The numerical simulations of the cerebral circulation help doctors to determine if the patient’s own vascular anatomy has the conditions to allow arterial stenting by endovascular method before the surgery or even evaluate the effect of different stent structure and materials. The results show that the flow downstream the aneurysm is highly modified by the stent configuration and that the best choice for reducing the flow in the aneurysm is to use a completely extended Endeavor stent.展开更多
Objective: To investigate the relationship between electroacupuncture (EA)-induced improvement of regional cerebral blood flow and the alternations of vasoactive intestinal peptide (VIP) and endothelin (ET) in rats wi...Objective: To investigate the relationship between electroacupuncture (EA)-induced improvement of regional cerebral blood flow and the alternations of vasoactive intestinal peptide (VIP) and endothelin (ET) in rats with experimental vascular dementia (VD). Methods: 40 Wistar rats were evenly randomized into sham-operation, model, medication (Nimotone) and EA groups. Vascular dementia model was established by repeated cerebral ischemia-reperfusion which was induced by occlusion and reopen of the bilateral common carotid arteries. EA (2～200 Hz, 2～3 mA) was applied to "Baihui"(GV 20), "Dazhui"(GV 14) and "Zusanli"(ST 36) for 30 min, once daily and continuously for 15 days. The regional cerebral blood flow (rCBF) in parietal lobe and hippocampus was determined with method of hydrogen clearance; a step-down avoidance test was adopted to observe the rats’ behavior change; and plasma VIP and ET contents were assayed by radioimmunoassay. Results: In comparison with sham-operation group, the correct rate of step-down avoidance test, rCBF in parietal lobe and hippocampus and plasma VIP level in VD model group lowered significantly (P<0.01) and plasma ET increased considerably (P<0.01). However, compared with model group, the correct rate of step-down avoidance test, rCBF values and plasma VIP in EA group raised obviously while plasma ET declined significantly. No significant differences were found between EA and medication groups in the 4 indexes. Conclusion: EA can raise rCBF in the parietal lobe and hippocampus, elevate plasma VIP level and reduce plasma ET in rats with VD.展开更多
文摘We present numerical simulations of blood flow through a brain vascular aneurysm with an artificial stent using Smoothed Particle Hydrodynamics (SPH). The aim of this work is to analyze how the flow into an aneurysm changes using different stent configurations. The initial conditions for the simulations were constructed from angiographic images of a real patient with an aneurysm. The wall shear stresses, pressure and highest velocity within the artery, and other particular quantities are calculated which are of medical specific interest. The numerical simulations of the cerebral circulation help doctors to determine if the patient’s own vascular anatomy has the conditions to allow arterial stenting by endovascular method before the surgery or even evaluate the effect of different stent structure and materials. The results show that the flow downstream the aneurysm is highly modified by the stent configuration and that the best choice for reducing the flow in the aneurysm is to use a completely extended Endeavor stent.
文摘Objective: To investigate the relationship between electroacupuncture (EA)-induced improvement of regional cerebral blood flow and the alternations of vasoactive intestinal peptide (VIP) and endothelin (ET) in rats with experimental vascular dementia (VD). Methods: 40 Wistar rats were evenly randomized into sham-operation, model, medication (Nimotone) and EA groups. Vascular dementia model was established by repeated cerebral ischemia-reperfusion which was induced by occlusion and reopen of the bilateral common carotid arteries. EA (2～200 Hz, 2～3 mA) was applied to "Baihui"(GV 20), "Dazhui"(GV 14) and "Zusanli"(ST 36) for 30 min, once daily and continuously for 15 days. The regional cerebral blood flow (rCBF) in parietal lobe and hippocampus was determined with method of hydrogen clearance; a step-down avoidance test was adopted to observe the rats’ behavior change; and plasma VIP and ET contents were assayed by radioimmunoassay. Results: In comparison with sham-operation group, the correct rate of step-down avoidance test, rCBF in parietal lobe and hippocampus and plasma VIP level in VD model group lowered significantly (P<0.01) and plasma ET increased considerably (P<0.01). However, compared with model group, the correct rate of step-down avoidance test, rCBF values and plasma VIP in EA group raised obviously while plasma ET declined significantly. No significant differences were found between EA and medication groups in the 4 indexes. Conclusion: EA can raise rCBF in the parietal lobe and hippocampus, elevate plasma VIP level and reduce plasma ET in rats with VD.
