Effects of Plaque Eccentricity on Biodegradable Polylactic Acid Stent Implantantion in Stenotic Vessels / 医用生物力学

Objective To study the effect of plaque eccentricity on stent performance and stress distributions of artery and plaque during stent implantation in stenotic vessels. Methods The stent and idealized stenotic vessels were constructed, and 4 different eccentricities (0%, 20%, 40%, 60%) were attributed to the plaque. Then the stent recoil, stent foreshortening, and stress distributions of artery and plaque when the stent was expanded to the target displacement were analyzed by the finite element method. Results Along with the increase of plaque eccentricity, both stent recoil and stent foreshortening gradually grew. At the same time, the stress of artery and plaque also showed an increasing tread, and high-stress areas gradually approached the narrow side. The maximum von Mises stress of the plaque was much greater than that of the artery. Conclusions Plaque eccentricity had a certain effect on performance of the stent and stress distributions of stenotic vessels. In stent design, the geometry of the plaque should be considered to improve clinical effect of the stent in interventional treatment.

Discussion on Strengthening Medical Supplies Management on Open Platform / 中国医疗器械杂志

We introduce the background of Shanghai medical purchasing service and supervision platform (later we call it "open platform") and the effect of its implementation. We also analyze the problems occurred by medical institutions in the management of supplies, explore how to use open platform to strengthen the management of medical supplies, further optimize the structure of supplies, standardize the clinical reasonable use and charges, and ensure the quality, safety and traceability of supplies.

Effects from Side Branch Diameter of Intracranial Aneurysm on Hemodynamic Parameters after Flow Diverter Implantation / 医用生物力学

Objective To comprehensively consider the effect of low diverter (FD) implantation on aneurysmal sac and its branches, so as to provide references for making a more reasonable surgical strategy for intracranial aneurysm embolization in clinical practice. Methods Based on computational fluid dynamics (CFD) method, the FD implantation procedure was simulated by using porous media model innovatively. Changes in hemodynamic parameters of aneurysmal sac and side branch with different diameters before and after FD implantation were compared and analyzed, such as blood flow field, velocity, wall pressure and wall shear stress (WSS). Results FD changed the hemodynamic characteristics of aneurysms. The blood flow velocity decreased significantly. The WSS on aneurysmal neck increased, while the difference of WSS between proximal and distal cervical area reduced conversely. Different side branch diameters of vessels had different effects on hemodynamic characteristic changes. The larger diameter would cause the greater blood flow reduction in side branch after FD implantation, but the decrease in velocity of aneurysmal sac and pressure on aneurysmal roof became smaller simultaneously. Meanwhile, the increase of WSS on aneurysmal neck was inversely proportional to the diameter of side branch. Conclusions The larger branch diameter of vessels would cause the worse effect of FD embolization therapy for intracranial aneurysm, worse atherosclerosis improvements and greater possibilities of branch occlusion or other ischemic complications. Doctors should pay more attention to such cases in FD interventional intravascular embolization in clinic.

Sensitivity Analysis of Flow Diverter Treatment of Intracranial Aneurysm Using Porous Media Model / 医用生物力学

Objective To simulate the hemodynamic effects of different flow diverters (FD) parameters by using computational fluid dynamics (CFD) technology, so as to develop a more reasonable FD embolization strategy before operation. Methods The porous media model was used to simulate the process of FD implantation into aneurysms, and the initial values of its own unique porous media momentum source parameters (permeability and inertial resistance) were calculated for a specific FD (Tubridge).The changes of hemodynamic parameters such as blood flow velocity, wall shear stress (WSS), volume flow and pressure of aneurysm-roof were compared under different situations (initial values of 80%, 90%, 100%, 110% and 120%), and the sensitivity analysis on hemodynamic parameters of patient-specific intracranial aneurysms (IA) for the porous media model was further conducted. Results The sensitivity of IA hemodynamic parameters to the permeability of porous media model was as follows: WSSparent-artery＞WSSaneurysm＞paneurysmal-roof, but the sensitivity to inertia resistance was relatively lower. Conclusions By using the porous media model, different metal coverages (MC) of FD could be simulated by choosing different permeability parameters, so it is necessary to adjust specific permeability settings during modeling of FD with different MC.

Influence of Fixation Methods on Fixation Effects of Femoral Neck Fracture / 医用生物力学

Objective To study the influence of hollow screws with five kinds of spatial distributions on the fixation effect of femoral neck fracture. Methods Geometric models of femoral neck fracture with Pauwels type I, II and III were built by reverse engineering according to CT images of the femur. Based on the finite element analysis software ANSYS, the stress distributions of internal fixation, head side and stem side of femoral neck and the displacement distributions of the model fixed by different methods were obtained. Results For femoral neck fracture with Pauwels type I, II and III, the maximum stresses at head side of femoral neck were the inverted triangle fixation method, two-screw parallel fixation method, two-screw parallel fixation method, respectively. The maximum stresses at stem side of femoral neck were the inverted triangle fixation method, inverted triangle fixation method and two-screw parallel fixation method, respectively. The minimum stresses on the screws were the cross fixation method, and the minimum displacements of the model were double-supported fixation method. Conclusions The probability of screw deformation and fracture is the smallest for cross fixation method. Inverted triangle fixation method can provide a good mechanical environment for fracture site. For femoral neck fracture with Pauwels typeⅠ and Ⅲ, double-supported fixation method has the strongest ability to prevent femoral neck shortening. While for femoral neck fracture with Pauwels typeⅡ, cross fixation method has the strongest ability to prevent femoral neck shortening.

Detection and Rectification of Radiation Emission from Medical Laser Equipment / 中国医疗器械杂志

By introducing the unqualified cases of radiation emission test of medical laser equipment, this paper analyses the causes of the problems and the corrective measures adopted, and analyses the effectiveness of the corrective measures. It is proposed that the design rules and rules related to radiation emission should be mastered from the input stage of product design and development, and the radiation emission problem should be considered and solved as soon as possible.

Characteristics of left atrial function real-time three plane strain rate imaging in patients with hypertension and coronary artery stenosis and their significances / 吉林大学学报(医学版)

Objective:To investigate the characteristics of real-time three plane strain rate imaging of left atrial function in the patients with primary hypertension and coronary artery stenosis, and to evaluate its clinical application value.Methods:Total 82 patients with primary hypertension were selected and divided into primary hypertension group (EH group,n=42)and primary hypertension complicated with coronary artery stenosis group (EHCHD group,n=40).In addition,the physical examination people were selected as control group (n=42).All the subjects were examined by conventional echocardiography,and the left atrial function in real-time three plane strain rate imaging was analyzed.The parameters of conventional echocardiography and real-time three plane strain rate imaging were compared.Results:Compared with control group,the systolic left atrial mean peak strain rate (SRs),early diastolic left atrial mean peak strain rate (SRe)and SRe/SRa of the patients in EH group and EHCHD group were significantly decreased (P < 0.05);the atrial systolic mean peak strain rate (SRa)and Time-SRa in EH group and EHCHD group were significantly increased (P <0.05).Compared with EH group,SRs,SRe and SRe/SRa in EHCHD group were obviously decreased (P < 0.05 );SRa and Time-SRa were significantly increased (P <0.05).Conclusion:Real-time three plane strain rate imaging can easily and accurately analyze the left atrial function in the patients with essential hypertension and coronary artery stenosis,it is worth to popularize in clinical application.

Numerical simulation of the internal noise in the pressure generator of a continuous positive airway pressure ventilator / 生物医学工程学杂志

It is important to overcome the problem of noise for the research and development of ventilator technologies. Previous research of this subject showed that the pressure generator, produced by German EMB-PAPST Company and specially used for continuous positive airway pressure (CPAP) ventilator, created noise easily, due to local backflow in the volute, uneven velocity distribution in the impeller and local negative pressure in the inlet of the impeller. Based on the previous research, a combination of the computational fluid dynamics (CFD) software FLUENT and steady-state solution of noise source of Reynolds-Averaged Navier-Stokes (RANS) was used in this study. We combined equation of Lilley and Synthetic Turbulence to get the information about speed fluctuation of the pressure generator, which is used to finish noise prediction. After detailed analysis, it showed that noise source of different degrees spreaded around the inlet of the impeller and the volute, interface of blade edge and corner of the volute tongue, which influenced its overall performance to certain extent. Therefore, its structural design needs to be improved.

Application of link mechanism in otolaryngology chair / 中国医疗器械杂志

Design otolaryngology chair's up-down assemble by applying link mechanism. And analysing the speed and accelerate of mechanism in CATIA's motion mechanism module to verify its actual running status. Draw the effective design, make the successful prototype.

The numerical simulation of the internal flow field inside the pressure generator of a continuous positive airway pressure ventilator / 生物医学工程学杂志

The problem of noise in ventilator has always been an important topic to study in the development of the ventilator. A great number of data are showing that there are still large gaps of research and application levels in noise control of the ventilator between China and some more advanced foreign countries. In this study, with cooperation of the Shanghai Medical Equipment Limited Liability Company, we used the computational fluid dynamics (CFD), software FLUENT, adopted the standard k-epsilon turbulence model and the SIMPLE algorithm to simulate the inner flow field of the continuous positive airway pressure (CPAP) ventilator's pressure generator. After a detailed analysis, we figured out that there are several deficiencies in this ventilator, like local reflow in volute, uneven velocity distribution and local negative pressure in inlet of the impeller, which easily lead to noise and affect the ventilator's performances. So, it needs to be improved to a certain extent.

Research on flow characteristics in a non-blade centrifugal blood pump based on CFD technology / 生物医学工程学杂志

The problem of thrombus and hemolysis in blood pump has always been an important topic to study in the development of the blood pump. Numbers of research results show that it is the complicated flow and the high shear stress of the mechanical movement that result in the thrombus and hemolysis. In this study, with the cooperation of Shanghai Children's Medical Center, we have used computational fluid dynamics (CFD) commercial software FLUENT to compute and analyze the flow characteristics in a non-blade centrifugal blood pump. The results figure out that this pump has a reasonable flow distribution and the shear stress distribution is under the critical broken state of red blood cell; meanwhile, there is less thrombus and hemolysis in this pump. So it is in the foreground for clinical use.