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Objective: To evaluate the safety and efficacy of transcatheter aortic valve replacement (TAVR) with domestic prostheses in patients with severely stenotic bicuspid aortic valve (BAV). Methods: This study was a prospective single-center non-randomized controlled study. Patients with symptomatic severe aortic stenosis (AS), who underwent TAVR with domestic prostheses at the First Affiliated Hospital of Air Force Medical University from January 2016 to April 2020 were consecutively included in our study. Patients were divided into BAV group and tricuspid aortic valve (TAV) group according to the aortic valve morphology. Baseline characteristics, procedural outcomes were compared between the two groups, and the primary endpoint was one-month all-cause mortality. Results: A total of 100 patients aged (69.8±8.9) years were enrolled, including 71 (71%) males. There were 51 cases in BAV group and 49 cases in TAV group. Compared with TAV group, patient in the BAV group was younger ((67.1±8.6) years vs. (72.7±8.4) years, P=0.002) and had larger ascending aortic diameter at proximal part ((39.7±5.7) mm vs. (36.0±4.2) mm, P<0.001), lower Society of Thoracic Surgeons-Predicted Risk of Mortality (STS-PROM) score (3.1 (1.9, 5.4) % vs. 5.9 (2.6, 12.3) %, P=0.002). In BAV group and TAV group, the incidence of 2nd prosthesis implantation was 15.7% (8/51) and 18.4% (9/49) (P=0.721), the incidence of moderate or severe paravalvular regurgitation was 2.0% (1/51) and 0 (P=1.000), the rate of device success was 82.4% (42/51) and 81.6% (40/49) (P=0.925), respectively. One-month all-cause mortality was 2.0% (1/51) and 10.2% (5/49) (P=0.108), respectively. Echocardiography showed that postprocedural mean pressure gradient (PGmean) was higher in the BAV group (13.0 (10.0, 16.0) mmHg vs. 9.0 (7.0, 14.0) mmHg, P=0.003) (1 mmHg=0.133 kPa), but the PGmean decrease post procedure as compared with that before TAVR was similar between the two groups ((36.7±16.6) mmHg vs. (36.2±17.5) mmHg, P=0.893). Conclusion: Favorable safety and efficacy are evidenced in patients with severely stenotic BAV undergoing TAVR with domestic prostheses.
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<p><b>PURPOSE</b>This study aims to explore the biomechanical mechanism of lower limb injuries to the driver by establishing a finite element (FE) simulation model of collisions.</p><p><b>METHODS</b>First a minibus FE model was integrated with a seat belt system. Then it was used to rebuild two collisions together with the total human model for safety (THUMS) provided by Toyota Motor Corporation: a rear-end collision between a minibus and a truck and a head-on collision of a minibus to a rigid wall. The impact velocities of both collisions were set at 56 km/h. The vehicle dynamic response, vehicle deceleration, and dashboard intrusion in the two collisions were compared.</p><p><b>RESULTS</b>In the minibus rear-end truck collision, the peak values of the von Mises equivalent stress at the tibia and the femur were 133 MPa and 126 MPa respectively; while in the minibus head-on rigid wall collision, the data were 139 MPa and 99 MPa. Compared with the minibus head-on rigid wall collision, the vehicle deceleration was smaller and the dashboard intrusion was larger in the minibus rear-end truck collision.</p><p><b>CONCLUSION</b>The results illustrate that a longer dashboard incursion distance corresponds to a higher von Mises equivalent stress at the femur. The simulation results are consistent with the driver's autopsy report on lower limbs injuries. These findings verify that FE simulation method is reliable and useful to analyze the mechanisms of lower limb injuries to the driver in minibus frontal collisions.</p>
Subject(s)
Humans , Accidents, Traffic , Automobile Driving , Biomechanical Phenomena , Finite Element Analysis , Lower Extremity , Wounds and InjuriesABSTRACT
Objective In order to fully reconstruct the accident by utilizing pedestrian injuries information gained from the car-pedestrian collision, a new method based on finite element simulation and genetic neural network to deduce the car-pedestrian collision parameters in reverse is proposed. Methods Crash simulations from different contact angles (back, left, front, right) at different impact speeds (25, 40, 55 km/h) were conducted by using Hyperworks and LS-DYNA, so as to obtain the head injury criterion (HIC) value and the maximum velocity of the thoracic wall. According to the criteria of injury biomechanics, the severities of the pedestrian head and thorax and corresponding injury locations were analyzed and set as predictors, and the predictive values of collision parameters were then acquired by using genetic neural network. Finally, this method was verified by two car-pedestrian accidents with the video and exact collision parameters. Results For both cases of the car-pedestrian accidents, the car speeds at the collision of pedestrian were 54 and 49 km/h, respectively, and the car-pedestrian contact angles were both 180°. While according to the pedestrian injuries information, the predictive values of the car speeds at the collision of pedestrian were 51 and 43 km/h, and the predictive values of the car-pedestrian contact angles were 184° and 169°, respectively. The reconstruction accuracies of two cases were 0.94 and 0.88. Conclusions The proposed method in the study can be used to predict car-pedestrian collision parameters efficiently and accurately by utilizing the pedestrian injuries information, which provides a new method for cause analysis and responsibility recognition, as well as theoretical references for the treatment and protection of head and thoracic injuries occurred in the car-pedestrian collision.
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Objective To study the relationship between the severity of pedestrian head injury and the impact speeds, the vehicle types and the impact positions in pedestrian-vehicle accidents by computer simulation based on the real accident video. Methods A pedestrian-traffic accident with the video was reconstructed by the MADYMO multi-body dynamics software to obtain the initial and boundary conditions. Experimental impact simulations were conducted on different vehicles (car, SUV and minibus) and pedestrian impact positions (front, side and back structure) by different speeds (20, 30, 40, 50 and 60 km/h) to analyze head injuries, and the simulation results were validated by two real pedestrian-vehicle accidents. Results Not only the impact speed and the front structure influenced the pedestrian head injury severity, but also the impact position of pedestrian was an important factor. At the collision speed ≤30 km/h, the pedestrian head injury caused by the contact with the ground could be possibly more serious than the contact with the vehicle; while at the collision speed≥40 km/h, the pedestrian head injury was mainly caused by the contact with the vehicle. Conclusions The pedestrian traffic accident can be accurately reconstructed by using the real accident video to analyze the pedestrian head dynamic response. The severity of pedestrian head injuries can be effectively reduced by speed limitations on different types of vehicles at pedestrian traffic accident black-spots.
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<p><b>OBJECTIVE</b>To establish an animal model to replicate the blunt impact brain injury in forensic medicine.</p><p><b>METHODS</b>Twenty-four New Zealand white rabbits were randomly divided into control group (n equal to 4), minor injury group (n equal to 10) and severe injury group (n equal to 10). Based on the BIM-II Horizontal Bio-impact Machine, self-designed iron bar was used to produce blunt brain injury. Two rabbits from each injury group were randomly selected to monitor the change of intracranial pressure (ICP) during the impacting process by pressure microsensors. Six hours after injury, all the rabbits were dissected to observe the injury morphology and underwent routine pathological examination.</p><p><b>RESULTS</b>Varying degrees of nervous system positive signs were observed in all the injured rabbits. Within 6 hours, the mortality rate was 1/10 in the minor injury group and 6/10 in the severe injury group. Morphological changes consisted of different levels of scalp hematoma, skull fracture, epidural hematoma, subdural hematoma, subarachnoid hemo- rrhage and brain injury. At the moment of hitting, the ICP was greater in severe injury group than in mild injury group; and within the same group, the impact side showed positive pressure while the opposite side showed negative pressure.</p><p><b>CONCLUSIONS</b>Under the rigidly-controlled experimental condition, this animal model has a good reproducibility and stable results. Meanwhile, it is able to simulate the morphology of iron strike-induced injury, thus can be used to study the mechanism of blunt head injury in forensic medicine.</p>
Subject(s)
Animals , Rabbits , Brain Injuries , Head Injuries, Closed , Intracranial Pressure , Reproducibility of Results , Wounds, NonpenetratingABSTRACT
<p><b>OBJECTIVE</b>To analyze the injuries of motorcyclists involved in fatal motorcycle frontal crashes.</p><p><b>METHODS</b>A survey group involving multi-discipline experts was built to randomly collect data on fatal motorcycle frontal collision accidents that occurred in Chongqing during 2006-2010. The sampled information included medical or autopsy reports, blood alcohol concentration (BAC) level, helmet use, accident witness, field sketch as well as field photos. The motorcyclist injuries were scored according to the Abbreviated Injury Scale (AIS) 2005. The involved riders with a BAC level larger than or equal to 20 mg/ml were attributed to alcohol use. Data were processed statistically with nonparametric test via software SPSS 11.0.</p><p><b>RESULTS</b>A total of 86 fatal motorcycle frontal crashes were sampled and further analyzed. The age of motorcyclists enrolled in this investigation showed nominal distribution and the middle-aged (30-39 years) occupied the highest percentage of fatalities. There were only 14 motorcyclists (16.3%) wearing helmets at the moment of collision. And 12.8% of these motorcyclist crashes were attributable to alcohol use. Impact injury was the main fatal cause, accounting for 72% of motorcyclist deaths, followed by tumbling injury (26%) and run-over (2%). Respectively 84%, 22% and 19% of motorcyclists who sustained head, chest and abdominal trauma died. Extremity injury was the most frequently observed injury type.</p><p><b>CONCLUSIONS</b>This investigation is helpful to build accident prevention programs and develop protection devices which may effectively mitigate injuries and prevent deaths following motorcycle frontal collision accidents. Further investigations on motorcycle collision accidents are still needed.</p>
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Humans , Abdominal Injuries , Accidents, Traffic , China , Craniocerebral Trauma , Head Protective Devices , MotorcyclesABSTRACT
<p><b>OBJECTIVE</b>By studying the mode and morphologic character of high fall injuries on the scene, and exploring the injury situation of different heights, different fall ways and postures, to provide a reference for the forensic identification of high fall injury.</p><p><b>METHODS</b>All the high fall cases were statistically analysed according to their gender, age, ground-touching posture, fall height, site and type of the injury.</p><p><b>RESULTS</b>Among 134 high fall cases, 98 were male and 36 were female with the age ranging from 2-71 years (37.6+/-16.9 on average), in which, 10-60 years old group consisted of 110 cases (82%). Most cases fell from windows or roofs (73%) and the touching objects were cement ground or shaft bottom of elevators. Among these cases, head injury was generally serious, followed by chest and abdominal injuries. The morphologic changes depend upon the height, nature, as well as the posture at the point while the body touches the ground.</p><p><b>CONCLUSION</b>Morphologic study of high fall injury assists medicolegal physicians to make correct identifications of the cause and nature of high fall injuries.</p>
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Adolescent , Adult , Aged , Child , Child, Preschool , Female , Humans , Infant , Male , Middle Aged , Accidental Falls , Mortality , Cause of Death , China , Epidemiology , Forensic Medicine , Posture , Trauma Severity Indices , Wounds and Injuries , Diagnosis , MortalityABSTRACT
<p><b>OBJECTIVE</b>To investigate the expression of Caspase-3 and Hsp70 in rabbits after severe traumatic brain injury (TBI) and to explore the feasibility of its application in estimation of injury time in forensic medicine.</p><p><b>METHODS</b>A rabbit model of heavy TBI was developed by high velocity impact on the parietal bone with an iron stick. Totally 8 healthy adult New Zealand white rabbits were randomly divided into control group (n equal to 2) and injury group (n equal to 6). Four hours after injury, tissue specimens from the parietal lobe, temporal lobe, occipital lobe, cerebellum and brainstem were harvested to detect the expression of Hsp70 and Caspase-3 by immunohistochemistry. Besides, the gray values of cells positive for Hsp70 and Caspase-3 were analyzed with an image analyzer.</p><p><b>RESULTS</b>Immunohistochemistry staining demonstrated a low level of Caspase-3 and Hsp70 expression in normal control group. While in injury group, both the Caspase-3 and Hsp70 expression was significantly elevated (P less than 0.05). Positive cells gathered around the lesion focus. Occipital lobe and cerebellum had fewer positive cells while temporal and brainstem had the fewest.</p><p><b>CONCLUSION</b>The expression of Caspase-3 and Hsp70 at an early stage following severe TBI is characteristic and can be applied to estimate the time of injury.</p>
Subject(s)
Animals , Rabbits , Brain Injuries , Metabolism , Caspase 3 , Metabolism , HSP70 Heat-Shock Proteins , Metabolism , Immunohistochemistry , Random AllocationABSTRACT
<p><b>OBJECTIVE</b>To study the patterns and morphologic characteristics of blunt head injury and analyse its formative mechanism in attempt to provide references for medicolegal expertise.</p><p><b>METHODS</b>The statistical analysis was done in terms of gender, age, as well as the nature, pattern, location, and feature of the injuries.</p><p><b>RESULTS</b>Among the 202 cases of head injury-induced death, 124 were male and 78 female with the age ranging from 1-81 years. Death caused by homicide was dominant (106, 52.5%), followed by suicide (49, 24.3%) and accident (44, 21.8%). The majority of suicide-induced death were by falling from height, and traffic crash was responsible for majority of unexpected death cases. The morphology and pathogenesis of the injuries varied according to differences on the mode, magnitude, and orientation of the outside force giving rise to blunt injury as well as the character of vulnerants.</p><p><b>CONCLUSION</b>Studies on the morphology and its formative rationale of blunt head injury will offer easy access to medicolegal expertise on the mode and character of the injury.</p>
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Adolescent , Adult , Aged , Aged, 80 and over , Child , Child, Preschool , Female , Humans , Infant , Male , Middle Aged , Cause of Death , China , Epidemiology , Forensic Medicine , Head Injuries, Closed , MortalityABSTRACT
<p><b>OBJECTIVE</b>To introduce a new animal model of graded mechanical primary brainstem injury (BSI).</p><p><b>METHODS</b>Altogether 45 rabbits were subjected to BSI by type II biological impact machine designed by the Third Military Medical University. The animals were divided into 4 experimental groups (n equal to 10) and 1 control group (n equal to 5) according to different magnitudes of impact pressure imposed on the occipital nodule: Group 1, 500-520 kPa; Group 2, 520-540 kPa; Group 3, 540-560 kPa; Group 4, 560-580 kPa and Group 5, 0 kPa with 20 kPa increase in each grade. The impact depth was a constant 0.5 cm. After injury, the clinical symptoms and signs as well as pathological changes were observed.</p><p><b>RESULTS</b>Rabbits in Group 1 revealed mild physiological reaction of BSI. They had localized cerebral contusion with punctate hemorrhage and subarachnoid hemorrhage (SAH) was limited to the peripheral tissues at the impact area. In Group 2, obvious physiological reaction was observed. Local pathological lesions reached the superficial layer of brainstem tissues; focal hemorrhage and girdle-shaped SAH in basilar pon were observed under microscope. In Group 3, BSI was more severe with a long respiratory depression. Pathological lesions reached the inner portion of brainstem with massive hemorrhage and the whole brainstem was wrapped by subarachnoid hematoma. In Group 4, most rabbits died due to severe BSI. Pathological lesions deepened to the central brainstem with wide pathological change, rapture of the medulla oblongata central canal. Group 5 was the control group, with normal brainstem structure and no lesion observed.</p><p><b>CONCLUSION</b>This model successfully simulates different levels of brainstem mechanical injury and clearly shows the subsequent pathological changes following injury. It takes two external parameters (impact pressure and depth) and has a similar injury mechanism to clinical accelerating BSI. Moreover it is reproducible and stable, thus being be- neficial for exploring pathophysiological mechanism, diagnosis and forensic identification of various degrees of BSI.</p>
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Animals , Rabbits , Brain Stem , Wounds and Injuries , Disease Models, Animal , PressureABSTRACT
Objective To investigate the design approaches and manufacturing techniques for the calibration system of side impact dummy neck. Method The ES-2 side impact dummy neck was selected as the research subject and a set of calibration system of ES 2 side impact dummy neck was developed in this experiment according to the pendulum impact theory, and the new design approaches and new manufacturing techniques suitable for the present industrial conditions in China were created to establish its two key components: the pendulum device and the head-neck flexion angle measurement device. The optimal designs for the quality distribution and inertia moment distribution of the whole pendulum were also carried out to assure the pendulum initial velocity and the pendulum impact velocity time curve during the pendulum absorber impact, while optimal designs for three angle sensors and the complex stereoscopically dependent relationship among those three sensors were carried out to assure the reliability of the head neck flexion angle measurement device. Correspondingly, a total of six calibration tests were carried out to validate this calibration system in terms of the technical requirements of ECE R95. Results The pendulum initial velocity of 3.36～3.48 m/s and the pendulum impact velocity time curve during the pendulum absorber impact, which were generated by the pendulum device in this calibration system of ES 2 side impact dummy neck, were in accordance with the ECE R95. Meanwhile, the head neck flexion angle measurement device of this calibration system was sufficient to detect the following three target angle values more accurately: the maximum values of fore pendulum base angles, the maximum values of aft pendulum base angles, and the maximum values of head neck complex flexion angles. Conclusions The calibration system of ES-2 side impact dummy neck is basically capable of meeting the demands of the existing international rule, the ECE R95. Besides, this neck calibration system is convenient and practical, and its design approaches and manufacturing techniques are likely to find the wider application in the impact biomechanics field.
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Objective To study the effect of continuous low frequency resonance on blood pressure, heart rate, breath rate and body temperature of the rat so as to provide basic data for the study of organs’ resonance injury and its reaction. Method Thirty two SD rats were divided into four groups randomly: false vibration group, 3 Hz vibration group, 6 Hz vibration group and 21 Hz vibration group. Femoral artery intubatton was given after anaesthesia with 1.5% sodium pentobarbital. All the rats were fastened on their back on the vibration platform staying calmly for 30 min. Then the vibration groups were given sine wave vibration with 5 mm amplitude(p-p), while the blood pressure, heart rate, breath rate and body temperature of the rats were measured at 0, 1, 3, 5, 10, 30, 60, 120, 180, 240, 300 and 360 min. The above physiological data were also observed in false vibration group at corresponding time. Results Continuous low frequency resonance could cause the blood pressure, heart rate, breath rate of the rat to rise rapidly after 1 min of vibration, and to reach the maximum value after 1 min to 3 min of vibration, and then to descend gradually and to be lower than the normal value after 30 min of vibration. The body temperature of the rat did not change at the beginning of vibration, but descended gradually after 10 min of vibration. At the beginning of vibration, the effect of 6 Hz resonance on blood pressure, heart rate, breath rate was dominating, while at the later stage, 3 Hz resonance was dominating. But the effect of the two frequencies on body temperature was accordant. Conclusions Continuous low frequency resonance can cause the blood pressure, heart rate, breath rate of the rat to rise rapidly at the beginning of vibration and then to descend gradually, and it can also depress the ability of body temperature regulation in rats.
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Objective to research the mechanical style(compressive or tensile force)of the key site of brain tissue in brain deceleration impact.Method a transparent physical brain model with air bubbles was built and loaded on an upright brain decaler ation impacting expedmentel platform.Then,the moveable platform was made a free fall from a height of 400mm and impacted on the fixed platform,and the whole deceleration impacting process was recorded by a high-speed video camera.Using the serial pictures analyzing Software,the length change of the long ads(vertical to the impacting direction)and the short axis(in the impacting di-rection)of the air bubbles were analyzed and calculated.Result the length change of the long axis of air bub-ble with in site coup was smallerthan the absolute value of that of the short axis;while with the air bubble in the contrecoup site,the length change of the long axis was bigger than the absolute value of the short axis.Conclusions the results showed that the air bubble in the coup site mainly suffered from the tensile force vertical to the impacting direction and the air bubble in the contrecoup site mainly suffered from the compres-sive force in the impacting direction.Since the propeny of tensile resistance of the brain tissue is inferior to the property of compressive resistance of the brain tissue, the injury is often easier to occur in the contrecoup site than in coup site. The results were of significance to the research of biomechanical mechanism, diagnosis and prevention of the brain deceleration impacting injury.
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Objective to research the mechanical style(compressive or tensile force)of the key site of brain tissue in brain deceleration impact.Method a transparent physical brain model with air bubbles was built and loaded on an upright brain decaler ation impacting expedmentel platform.Then,the moveable platform was made a free fall from a height of 400mm and impacted on the fixed platform,and the whole deceleration impacting process was recorded by a high-speed video camera.Using the serial pictures analyzing Software,the length change of the long ads(vertical to the impacting direction)and the short axis(in the impacting di-rection)of the air bubbles were analyzed and calculated.Result the length change of the long axis of air bub-ble with in site coup was smallerthan the absolute value of that of the short axis;while with the air bubble in the contrecoup site,the length change of the long axis was bigger than the absolute value of the short axis.Conclusions the results showed that the air bubble in the coup site mainly suffered from the tensile force vertical to the impacting direction and the air bubble in the contrecoup site mainly suffered from the compres-sive force in the impacting direction.Since the propeny of tensile resistance of the brain tissue is inferior to the property of compressive resistance of the brain tissue, the injury is often easier to occur in the contrecoup site than in coup site. The results were of significance to the research of biomechanical mechanism, diagnosis and prevention of the brain deceleration impacting injury.
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Objective To observe the changes of the microvascular permeability after blunt chest trauma (BCT), endotoxemia and their combined injury in rats. Methods After the establishment of the rat models of BCT, endotoxemia and their combined injury in the right lungs, the fluorescein sodium (FINa) content was measured with flurospectrophotometer in lungs 0.5, 1, 4 and 8 h after injury. Results There was an early obvious increase of the microvascular permeability in the impact lateral (peak at half an hour after injury), and a delayed increase in the contralateral lung (peak at the 8th h) in the BCT group. The FINa content was higher in endotoxemia group than in the BCT group(P<0.05), and lower than that in the combined injury group(P<0.05) in the contralateral lung. Conclusion Results indicate that there were different pathophysiologic processes among the 3 kinds of injury and the FINa content is a useful index to manifest the changes of microvascular permeability in tissues.
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Objective To observe the changes of the microvascular permeability after blunt chest trauma (BCT), endotoxemia and their combined injury in rats. Methods After the establishment of the rat models of BCT, endotoxemia and their combined injury in the right lungs, the fluorescein sodium (FINa) content was measured with flurospectrophotometer in lungs 0.5, 1, 4 and 8 h after injury. Results There was an early obvious increase of the microvascular permeability in the impact lateral (peak at half an hour after injury), and a delayed increase in the contralateral lung (peak at the 8th h) in the BCT group. The FINa content was higher in endotoxemia group than in the BCT group(P<0.05), and lower than that in the combined injury group(P<0.05) in the contralateral lung. Conclusion Results indicate that there were different pathophysiologic processes among the 3 kinds of injury and the FINa content is a useful index to manifest the changes of microvascular permeability in tissues.