Research advances in nonalcoholic fatty liver disease-related hepatocellular carcinoma / 临床肝胆病杂志

The incidence rate of nonalcoholic fatty liver disease-related hepatocellular carcinoma (NAFLD-HCC) tends to increase worldwide, while its pathogenesis remains unclear. With reference to the literature in recent years, this article summarizes the role of adipose tissue inflammation, oxidative stress, gut microbiota, and insulin resistance in the pathogenesis of NAFLD-HCC and the advances in the prevention and treatment of the above mechanisms, so as to provide new ideas for the treatment of NAFLD-HCC.

Kinematics Study of Glenohumeral Joint at Different Arm Elevation Planes in Normal Chinese / 医用生物力学

Objective To investigate relative translations of the glenohumeral joint during abduction, scaption and forward flexion in normal Chinese, so as to provide references for diagnosis, treatment and follow-up of glenohumeral joint instability and subacromial impingement syndrome.Methods The biplanar fluoroscopy system combined with model-image registration technique were used to measure the humeral translation relative to the scapular in 13 healthy volunteers during abduction, scaption and forward flexion.Results The anterior-inferior glenohumeral translation during abduction, scaption and forward flexion was (4.0±1.3), (4.1±1.5),(4.8±1.9) mm, respectively. The superior-inferior glenohumeral translation was (3.0±1.0), (3.1±1.1), (3.3±1.5) mm, respectively. During the whole motion, there was a significant difference in superior-inferior translation at different arm elevation angles, while other significant differences were not found.Conclusions For normal Chinese, the humeral head was positioned posteriorly and superiorly on the glenoid. During forward flexion, the anterior-inferior and superior-inferior glenohumeral translation was the maxium. Therefore, in the process of clinical diagnosis, treatment and follow-up, patients performing the forward flexion may obtain a better evaluation effect.

Biomechanical Study of the Open-Type Stent Retriever / 医用生物力学

Objective To simulate the process of thrombus removal from the open-type stent retrievers, so as to provide theoretical references for the design and clinical application of the open-type stent retrievers. Methods Finite element models of the open-type stent retrievers with 3,4,5 supporting units (K3,K4,K5), the crimping tools, simulated vessels and simulated thrombus (three types) were established. Radial displacement load was applied on the crimping tool until the stent was crimped to 0.5 mm, and the maximum principal strain (MPS) peak and radial force (RF)of the stent were analyzed. When displacement of the crimping tool was restored, the stent self-expanded and contacted with blood vessels, and MPS of the stent and von Mises stress (VMS) of blood vessels were analyzed. Axial displacement was applied to proximal end of the stents to allow the stent to drive the clots to migrate, and the blood vessel VMS and withdrawal force of the stents (the ability to capture thrombus) were analyzed. ResultsThe MPS peaks for 3 types of stent retrievers during crimping process were 6.94%, 8.30% and 5.48%, which were all smaller than the 12% fracture limit. When the outer diameter of the stent was 3 mm (equal to the inner diameter of blood vessels), the K4 stent had the largest RF. The results of self-expanding release process showed that the larger the number of support units, the greater the VMS of blood vessels. At the stage of thrombus migration and removal,the VMS of blood vessels was generally small and concentrated on the thrombus. The withdrawal force of the stent reached the maximum at the initial stage of thrombus migration and removal, then gradually decreased. The peak withdrawal force of the K4 stent was larger than that of the K5 and K3 stent. Conclusions Although the MPS and VMS for 3 types of open-type stent retrievers were within the safe range, the K4 stent showed better performance in RF and withdrawal force with the three types of thrombus. The research findings can provide the analysis methods and ideas for optimizing the open-type stent retrievers, to avoid clinical complications such as vascular injury and improve safety and effectiveness of the stent retrievers.

The Influence of Bending Parameters on Mechanical Properties of Soft Tissue Suture Passer Hook / 医用生物力学

Objective To explore the influence of hook deflection angle and inclination angle on mechanical properties of the soft tissue suture passer hook. Methods Taking the end face far away from the tip of the needle (end face 1) as the study object, a mathematical model was established with the moment as dependent variable and the hook deflection angle and inclination angle as the independent variable. The moment was solved by the mathematical model with the deflection angle and inclination angle of 0°, 10°, 20° and 30°. Based on the finite element analysis method, 16 three-dimensional geometric hook models with deflection angle and inclination angle of 0°, 10°, 20° and 30° were established by SolidWorks. The stress analysis was carried out by ANSYS Workbench. Under the same puncture force, the maximum von Mises stress of each hook and the reaction moment of end face far away from the tip of the needle were calculated. Results The results from theoretical analysis and numerical simulation showed that the reaction moment of end face 1 increased with the increase of deflection angle, and increased with the decrease of inclination angle. The hook with deflection angle of 0° and inclination angle of 30° had the minimum reaction moment. The finite element analysis results showed that with the deflection angle of 0°, the maximum von Mises stress of the hook was the smallest and did not change with the inclination angle of the hook changing. Conclusions The established mathematical model can accurately explain the relationship between the moment at the end face of the hook and the deflection angle and inclination angle of the hook. This study provides the theoretical basis for designing hook geometry of the soft tissue suture passer, and improves the safety of the soft tissue suture passer in operation process.

Research on influencing factors of hemolysis based on rolling blood pump / 国际生物医学工程杂志

Objective:To study the effects of rolling blood pump parameters and blood concentration on hemolysis during extracorporeal circulation.Methods:According to the extracorporeal hemolysis experiment standard, an extracorporeal circulation experimental device was built to analyze the influences of circulation time (0 ~ 90 min), blood flow rate (1~4 L/min), and blood volume fraction (60%, 70%) on the hemolysis of blood samples in the circulatory system. The results of hemolysis were analyzed using first-order linear regression.Results:The longer the blood pump circulation time, the greater the hemolysis rate; the higher the blood flow rate, the greater the hemolysis rate. When the flow rate is 1 and 2 L/min, the hemolysis rate curve has an inflection point that changes with time, i.e. when the circulation time exceeds 30 min, the slope of the hemolysis rate curve suddenly increases. However, when the flow rate is 3 and 4 L/min, the hemolysis mutation phenomenon is not obvious. Compared to the blood sample with blood volume fraction of 70%, a blood sample with a blood volume fraction of 60% is less prone to hemolysis.Conclusions:The longer the blood pump circulation time and the higher the blood flow rate, the more easily the red blood cells are destroyed, i.e. the hemolysis rate is directly proportional to the circulation time and blood flow rate. When the circulation time increases to a certain degree, an inflection point appears in the hemolysis rate curve, and the hemolysis trend will be significantly enhanced.

Influences from Implant Angle of Suture Anchors on the Maximum Pullout Force / 医用生物力学

Objective To make biomechanical evaluation on ultimate pullout strength of the suture anchors based on the angle of suture anchor (SA) implanted into the humerus during arthroscopic rotator cuff repair (RCR) surgery. Methods Polyurethane materials with densities of 0.16 g/cm3 and 0.32 g/cm3 were used to simulate osteoporosis and normal cancellous bone, and polyurethane materials with densities of 0.64 g/cm3 and 3 mm thickness were used to simulate human cortical bone. The two kinds of cancellous bone models were respectively adhered together with cortical bone model to construct human humerus model. Titanium metal suture anchors were inserted into humerus models at 45°, 60°, 75° and 90° angle, then the continuous tensile experiments were performed, and 45° pulling direction between the humerus model surface and suture anchor was used to simulate the supraspinatus physiological traction direction, and each group was continuously tested 8 times, recording the pullout strength and failure modes. ResultsThe pullout force of high-density bone models was significantly higher than that of low-density bone models (P＜0.001), and at the same density, compared with 45°, 60° and 75°, the implant angle of 90° has a larger pullout force (P＜0.01). Conclusions In the model of humerus, the 90° implantation of suture anchor showed better biomechanical properties, and the vertical implantation of anchor in the repair of rotator cuff was beneficial to the knotting during operation and postoperative recovery of the supraspinatus.

Injury of Levator Ani Muscles and Occurrence of Pelvic Floor Diseases during Vaginal Delivery Based on Finite Element Method / 医用生物力学

Objective To simulate the biomechanical characteristics of pelvic-ligament-muscle during vaginal delivery and rest, and to explore the injury of levator ani muscles during vaginal delivery, pelvic organ prolapse and stress urinary incontinence. Methods The three-dimensional (3D) nonlinear finite element model of pelvis-ligament-muscle was established to calculate the stress and strain distributions and injury of levator ani muscles under different abdominal pressures and loads. The stress and strain distributions as well as damage of type I, Ⅱ, Ⅲ stress urinary incontinence and pelvic organ prolapse were also calculated. Results The highest equivalent stresses of levator ani were 14, 29, 43, 86, 144, 230 kPa, respectively, when the abdominal pressure was 1 kPa under the load of 3, 5, 8 kPa and the abdominal pressure was 1.5 kPa under the load of 3, 5, 8 kPa. The stresses of type I, Ⅱ, Ⅲ stress urinary incontinence and pelvic organ prolapse were 1.69, 1.01, 0.70, 1.58 MPa. Conclusions Vaginal delivery would result in the damage to the puborectalis and the middle of the pubococcipital muscle, which was consistent with the damage of the anal levator muscle with pelvic floor dysfunction. This study uses scientific method to find out the exact location of pelvic floor injury during vaginal delivery, which can provide references for clinicians to prevent pelvic floor disease and formulate post natal rehabilitation training.

Research progress in mechanical thrombectomy device for deep venous thrombosis treatment / 国际生物医学工程杂志

Mechanical thrombectomy is a minimally invasive interventional method. Embolization device is too close to the blood vessel wall and venous valve in clinical applications, and it can cause blood vessel damage when it is sucked into the lumen. Embolization device is easy to cause hemolysis. Optimal design can reduce the damage to red blood cells, but it cannot be completely avoided; Shedding emboli can complicate the pulmonary artery. The clinical application studies of mechanical thrombectomy devices in the world was reviewed, including 74 experimental studies and 166 clinical application studies. The current status and causes of vascular injury, hemolysis and pulmonary embolism caused by mechanical thrombectomy were analyzed. This paper aims to make recommendations for the optimization of mechanical thrombectomy devices.

Influence Factors of the Thrombectomy Effects for Mechanical Thrombectomy Devices / 医用生物力学

Objective To investigate the influence of thrombus entrance shape, suction rate and blood flow velocity on thrombus aspiration of rotary cutting and suctioned thrombectomy devices, so as to provide theoretical support for the design and optimization of such devices. Methods Three models with different thrombus entrance shapes (‘L’-style, ‘8’-style and ‘0’-style) were established to study the influence of thrombus entrance shape on the thrombectomy; different suction rates (75, 100, 125, 150 mL/min) and different blood flow velocities (0-10 cm/s, at interval of 1 cm/s) were set to discuss how the suction rate and blood flow velocity affected the thrombectomy based on ‘8’-style thrombus entrance. Results The thrombus could not be aspirated evenly in ‘L’-style model, and there was no significantly difference in aspiration between ‘8’ -style model and ‘0’-style model. But the ‘8’-style model was better than ‘0’-style model in lateral thrombus suction. The suction rate that was greater than 100 mL/min provided a limited effect on improvement of thrombectomy effect. The best suction effect was reached when blood flow velocity was less than 1 cm/s, and the effect of thrombectomy was decreasing gradually with blood flow velocity increasing. Conclusions The thrombus entrance shape, suction rate and blood flow velocity had a great impact on thrombectomy greatly. A wide and short thrombus entrance shape, an appropriate increase of suction rate and decrease of blood flow velocity would contribute significantly to the improvement of thrombectomy effect. These results can be used as guidance for the optimal design of rotary cutting and suctioned thrombectomy devices.

Research progress in mechanical thrombectomy device for deep venous thrombosis treatment / 国际生物医学工程杂志

Mechanical thrombectomy is a minimally invasive interventional method. Embolization device is too close to the blood vessel wall and venous valve in clinical applications, and it can cause blood vessel damage when it is sucked into the lumen. Embolization device is easy to cause hemolysis. Optimal design can reduce the damage to red blood cells, but it cannot be completely avoided; Shedding emboli can complicate the pulmonary artery. The clinical application studies of mechanical thrombectomy devices in the world was reviewed, including 74 experimental studies and 166 clinical application studies. The current status and causes of vascular injury, hemolysis and pulmonary embolism caused by mechanical thrombectomy were analyzed. This paper aims to make recommendations for the optimization of mechanical thrombectomy devices.

Verification of small intestinal submucosa graft stent in vitro / 国际生物医学工程杂志

Objective To verify the feasibility of using small intestine submucosa for graft stents.Methods A Z-type Nitinol wire stent was used as the metal stent material,and porcine small intestine submucosa was used as the biofilm material to prepare the bio-coated stent.In vitro implantation,extracorporeal pulsation and extracorporeal flexion of the stents were designed based on the requirements for the small intestine submucosa graft stent implantation during the endovascular aneurysm repair and of the mechanical properties of the graft stent during human body activity.The feasibility of using small intestine submucosa for the graft stents was evaluated according to the patency of the stent lumen after the experiment,the presence or absence of cracks in the membrane,and the presence or absence of fracture of the metal stent.Results In the in vitro experiments,all the samples were able to maintain complete tunica and luminal patency except the 8th sample that showed suture rupture.Besides,all the samples showed good rebounding and adhering properties in both in vitro implantations and extracorporeal pulsation pressure experiments,and no dangerous problems were found such as film rupture,suture loss and stent fracture.Conclusion Small intestine submucosa can meet the durability requirements of graft stents,adapt to the conditions of graft stents such as implantation,bending and blood pulsation,and can be used as the covering material of graft stents.

Effects of strut numbers on biomechanical properties of Z-shaped stent-grafts / 医用生物力学

Objective To analyze the influence from strut numbers on biomechanical properties of Z-shaped stentgrafts,especially on their radial support performance and flexibility,so as to provide theoretical support for the design and clinical selection of Z-shaped stent-grafts.Methods Z-shaped stent-grafts with 5,8,10,12 struts were established by finite element method to simulate the process of compression and bending behavior.Radial displacements were applied on surface of the stent-graft and opposite rotations were applied around the z-axis,until a bending angle of 40° was reached.Then parameters such as stent stress,radial support force,strains in graft,cross-section deflection,bending torque were extracted to evaluate the performance of different stentgrafts.Results Compared with stent-grafts with more strut numbers,5-strut stent-graft showed a better radial support performance with the maximum radial force during compression,and it also generated the smallest 68 N · mm torque and 67.5％ cross-section deflection.The tensile strain in graft of 5-strut stent-graft during the process of bending was relatively smaller.Conclusions The strut number of Z-shaped stent-grafts has a significant influence on biomechanical properties of the stent-grafts.Especially the Z-shaped stent-graft with relatively fewer strut numbers shows an advantage in evaluating radial support performance and flexibility such as the bending torque and the cross-section deflection,and is more suitable to be anchored and fit to the tortuous blood vessel,which will play a positive role in decreasing the complication such as endoleaks and thrombosis.The research findings can guide structure design of Z-shaped stent-grafts and optimal selection for surgery.

Experimental study of temperature sensor in temperature-guided radiofrequency catheter ablation / 生物医学工程学杂志

In order to optimize temperature monitoring, the mean of temperature measured by Copper-CuNi thermocouple (TC) was compared with the actual temperature. By the use of the temperature response curve of TC, the data from monitoring temperature were analyzed in regard to the depth of installation, the diameter of TC hole and the material of ablation electrode. The accuracy and real-time of TC with a depth of 3.5 mm were better than those of 2.5 mm or 3 mm, when TC was installed in the ablation electrode TC hole. However, the difference of real-time performance was not obvious. When TC was installed in different TC holes with diameter of 0.44 mm, 0.42 mm, 0.33 mm respectively, TC with the diameter of 0.33 mm TC hole was noted to be of higher accuracy and better real-time to response temperature, compared with others. In terms of material quality, the slope of platinum temperature response curve was greater than that of stainless steel, while the accuracy of sensor temperature changed inconspicuously. As a result, the monitoring device of temperature should be put to the heat source as nearly as possible. Also, platinum ablation electrode with better thermal conductivity should be chosen.