This study explores the implementation of computed tomography(CT)reconstruction and simulation techniques for patient-specific valves,aiming to dissect the mechanical attributes of calcified valves within transcathete...This study explores the implementation of computed tomography(CT)reconstruction and simulation techniques for patient-specific valves,aiming to dissect the mechanical attributes of calcified valves within transcatheter heart valve replacement(TAVR)procedures.In order to facilitate this exploration,it derives pertinent formulas for 3D multi-material isogeometric hyperelastic analysis based on Hounsfield unit(HU)values,thereby unlocking foundational capabilities for isogeometric analysis in calcified aortic valves.A series of uniaxial and biaxial tensile tests is executed to obtain an accurate constitutive model for calcified active valves.To mitigate discretization errors,methodologies for reconstructing volumetric parametric models,integrating both geometric and material attributes,are introduced.Applying these analytical formulas,constitutive models,and precise analytical models to isogeometric analyses of calcified valves,the research ascertains their close alignment with experimental results through the close fit in displacement-stress curves,compellingly validating the accuracy and reliability of the method.This study presents a step-by-step approach to analyzing themechanical characteristics of patient-specific valves obtained fromCT images,holding significant clinical implications and assisting in the selection of treatment strategies and surgical intervention approaches in TAVR procedures.展开更多
Mitral valve reconstruction was performed on 41 patients from 1980 to 1991. Two died early and one died later.38 survivals were followed up in 3 to 108 months,35 cases'heart function improved to grades 1～2,3 case...Mitral valve reconstruction was performed on 41 patients from 1980 to 1991. Two died early and one died later.38 survivals were followed up in 3 to 108 months,35 cases'heart function improved to grades 1～2,3 cases to grade 3,they need small dose medication support.The operative indicationcontra-indication and the surgical technique are discussed.It is concluded that mitral valve reconstruction is suitable for membranaceous or simple thickness, but mitral valve replacement should be chosen when severe valve calcificatlon or sub-valve diseases are present.展开更多
Objective Tricuspid valve reconstruction was advocated as the operative method for the treatment of tricus-pid valve endocarditis recently. Many people accept that valve replacement therapy should be performed if more...Objective Tricuspid valve reconstruction was advocated as the operative method for the treatment of tricus-pid valve endocarditis recently. Many people accept that valve replacement therapy should be performed if more than two valve leaflets are involved. The aim of the study to discuss if reconstructive surgery could be done to treat two valve leaflets involved in tricuspid valve endocarditis. Methods A 17-year-old boy with ventricular septal defect (VSD) and tricuspid valve subacute endocarditis was surgical treated through extra-corporeal circulation. two-thirds of the defective septal cusp, and half of the defective anterior cusp were ex-cised during operation. The tricuspid valve was reconstructed with autologous pericardial strip, cusp com-missuroplasty and 4-0 prolene sutures made as chordae tendineaes. VSD was repaired using a pericardial patch. Results The patient was discharged post-operation with excellent restoration of the tricuspid valve ac-tivity. Cardiac ultrasound revealed normal tricuspid valve activity and low degree of regurgitation two years follow-up. Conclusions It seems that tricuspid valve reconstruction could be performed for two defective leaflets or half of the tricuspid valve.展开更多
A 46-year-old man was referred to our hospital due to severe ischemic mitral regurgitation with severe bileaflet tethering and a dilated left ventricle. We performed left ventricular reconstruction and mitral valve an...A 46-year-old man was referred to our hospital due to severe ischemic mitral regurgitation with severe bileaflet tethering and a dilated left ventricle. We performed left ventricular reconstruction and mitral valve annuloplasty combined with papillary muscle relocation. Although left ventricular continued remodeling occurred during follow-up, left ventricular reconstruction and mitral valve annuloplasty combined with papillary muscle relocation provided durable mitral repair, and his functional status was good. Thus, this combined surgical treatment may reduce mitral regurgitation recurrence after mitral valve annuloplasty.展开更多
Objective To investigate surgical technique and clinical outcomes of reconstruction of annulus and intervalvular fibrous body during valve replacements. Methods Fifty-nine patients underwent reconstruction of annulus ...Objective To investigate surgical technique and clinical outcomes of reconstruction of annulus and intervalvular fibrous body during valve replacements. Methods Fifty-nine patients underwent reconstruction of annulus or intervalvular fibrous body during valve replacement. Indications for operation were small展开更多
Operating principle of water three-way valve with high flow for individual hydraulic prop in coal was presented in this paper, its strict and precise mathematical model was established, its flow field was simulated nu...Operating principle of water three-way valve with high flow for individual hydraulic prop in coal was presented in this paper, its strict and precise mathematical model was established, its flow field was simulated numerically by software Fluent, and its dynamic characteristics were analyzed during the work process such as raising leg, loading and overflow, the influence of the related parameters on high-flow water three-way valve was determined. The results as follows： during the raising leg stage and early raising leg stage, when the damping ratio increases, the overshoot of system decreases and the setting time reduces, and the dynamic response performance has a significant improvement. During the loading stage and the overflow stage, the pressure in plunger chamber of single hydraulic prop, the output flow and the displacement of the high-flow water three-way valve decrease with the decreasing of the external load. The spring stiffness of the safety valve directs the flow and the spool＇s displacement of the safety valve, and it can be used to control the high-flow three-way valve＇s sensitivity.展开更多
Objective A novel high-speed three-way solenoid valve is developed, which is used for the common-rail injection system equipped on DME powered engine. In order to improve the dynamic response performance of the three-...Objective A novel high-speed three-way solenoid valve is developed, which is used for the common-rail injection system equipped on DME powered engine. In order to improve the dynamic response performance of the three-way solenoid. Methods Experimental studies have been conducted to investigate the effects of spool stroke, drive voltage, negative demagnetizing pulse and two drive schemes on the dynamic response performance of the three-way solenoid valve. Results The results show that the dynamic response performance of the three-way solenoid valve can be remarkably improved by shortening the spool stroke and increasing the drive voltage. Simultaneously, the difference between the response time of closing valve and that of opening valve decreases. At each different drive voltage, there exists an optimal negative demagnetizing pulse corresponding to the same positive exciting pulse. At this optimal pulse, the dynamic response performance of the three-way solenoid valve is the best. In addition, the high drive voltage can lead to the smaller optimal negative demagnetizing pulse. It is also indicated from the experiments that the dynamic response performance of the three-way solenoid valve is better when the NO.1 drive scheme is adopted. The lower drive voltage results in the larger difference between the dynamic response performances for the two drive schemes. Conclusion The dynamic response performance of a novel three-way solenoid valve is good.展开更多
Objective:While evidence-based clinical guidelines recommend chordal-sparing mitral valve replacement,rather than mitral valve repair,in patients with severe ischemic mitral regurgitation(IMR)undergoing coronary arter...Objective:While evidence-based clinical guidelines recommend chordal-sparing mitral valve replacement,rather than mitral valve repair,in patients with severe ischemic mitral regurgitation(IMR)undergoing coronary artery bypass grafting,there are no similar recommendations for patients undergoing left ventricular reconstruction(LVR).This study aimed to compare the clinical outcomes of mitral valve repair and replacement in patients undergoing LVR complicated by more than moderate IMR.Methods:In this single-center cohort study,a total of 74 consecutive patients who underwent LVR and mitral valve surgery(repair group:59;replacement group:15),during the period from March 2000 to March 2021 at Fuwai Hospital(Beijing,China)were retrospectively enrolled.Survival rates were calculated with the Kaplan-Meier method and compared using the log-rank test.Univariate Cox analysis was performed to evaluate possible confounders,followed by adjustment in multivariate analysis.The primary outcome was survival free of major adverse cardiovascular and cerebrovascular events(MACCE).Results:Median follow-up time was 59.4 months.Compared with mitral valve replacement,mitral valve repair was associated with increased risk of perioperative use of ventricular assist device(22.0%vs.0,P=0.045).There was no difference in overall survival(hazard ratio(HR),1.10;95%confidence interval(CI),0.31-3.93;Plogrank=0.888)and MACCE-free survival(HR,1.54;95%CI,0.65-3.65;Plogrank=0.319),even after multivariate Cox regression(HR,1.35;95%CI,0.37-4.88;PCox=0.646;and HR,1.41;95%CI,0.57-3.44;PCox=0.455,respectively).Furthermore,while no differences were observed in ejection fraction and left ventricular end-diastolic diameter on follow-up echocardiography,mitral valve repair was associated with an increased risk of recurrent mitral regurgitation(P=0.041).Conclusions:In patients undergoing LVR complicated by more than moderate IMR,both concomitant mitral valve repair and replacement can be successfully achieved with comparable overall and MACCE-free survival outcomes;however,mitral valve replacement may be superior to mitral valve repair for persistent correction of mitral dysfunction.展开更多
基金supported by the Natural Science Foundation of China(Project Nos.52075340 and 61972011)the Shanghai Special Research Project on Aging Population and Maternal and Child Health(Project No.2020YJZX0106).
文摘This study explores the implementation of computed tomography(CT)reconstruction and simulation techniques for patient-specific valves,aiming to dissect the mechanical attributes of calcified valves within transcatheter heart valve replacement(TAVR)procedures.In order to facilitate this exploration,it derives pertinent formulas for 3D multi-material isogeometric hyperelastic analysis based on Hounsfield unit(HU)values,thereby unlocking foundational capabilities for isogeometric analysis in calcified aortic valves.A series of uniaxial and biaxial tensile tests is executed to obtain an accurate constitutive model for calcified active valves.To mitigate discretization errors,methodologies for reconstructing volumetric parametric models,integrating both geometric and material attributes,are introduced.Applying these analytical formulas,constitutive models,and precise analytical models to isogeometric analyses of calcified valves,the research ascertains their close alignment with experimental results through the close fit in displacement-stress curves,compellingly validating the accuracy and reliability of the method.This study presents a step-by-step approach to analyzing themechanical characteristics of patient-specific valves obtained fromCT images,holding significant clinical implications and assisting in the selection of treatment strategies and surgical intervention approaches in TAVR procedures.
文摘Mitral valve reconstruction was performed on 41 patients from 1980 to 1991. Two died early and one died later.38 survivals were followed up in 3 to 108 months,35 cases'heart function improved to grades 1～2,3 cases to grade 3,they need small dose medication support.The operative indicationcontra-indication and the surgical technique are discussed.It is concluded that mitral valve reconstruction is suitable for membranaceous or simple thickness, but mitral valve replacement should be chosen when severe valve calcificatlon or sub-valve diseases are present.
文摘Objective Tricuspid valve reconstruction was advocated as the operative method for the treatment of tricus-pid valve endocarditis recently. Many people accept that valve replacement therapy should be performed if more than two valve leaflets are involved. The aim of the study to discuss if reconstructive surgery could be done to treat two valve leaflets involved in tricuspid valve endocarditis. Methods A 17-year-old boy with ventricular septal defect (VSD) and tricuspid valve subacute endocarditis was surgical treated through extra-corporeal circulation. two-thirds of the defective septal cusp, and half of the defective anterior cusp were ex-cised during operation. The tricuspid valve was reconstructed with autologous pericardial strip, cusp com-missuroplasty and 4-0 prolene sutures made as chordae tendineaes. VSD was repaired using a pericardial patch. Results The patient was discharged post-operation with excellent restoration of the tricuspid valve ac-tivity. Cardiac ultrasound revealed normal tricuspid valve activity and low degree of regurgitation two years follow-up. Conclusions It seems that tricuspid valve reconstruction could be performed for two defective leaflets or half of the tricuspid valve.
文摘A 46-year-old man was referred to our hospital due to severe ischemic mitral regurgitation with severe bileaflet tethering and a dilated left ventricle. We performed left ventricular reconstruction and mitral valve annuloplasty combined with papillary muscle relocation. Although left ventricular continued remodeling occurred during follow-up, left ventricular reconstruction and mitral valve annuloplasty combined with papillary muscle relocation provided durable mitral repair, and his functional status was good. Thus, this combined surgical treatment may reduce mitral regurgitation recurrence after mitral valve annuloplasty.
文摘Objective To investigate surgical technique and clinical outcomes of reconstruction of annulus and intervalvular fibrous body during valve replacements. Methods Fifty-nine patients underwent reconstruction of annulus or intervalvular fibrous body during valve replacement. Indications for operation were small
基金Supported by the National Natural Science Foundation of China （51075001） the Nature Science Research Project of Anhui Province （KJ2009A020）
文摘Operating principle of water three-way valve with high flow for individual hydraulic prop in coal was presented in this paper, its strict and precise mathematical model was established, its flow field was simulated numerically by software Fluent, and its dynamic characteristics were analyzed during the work process such as raising leg, loading and overflow, the influence of the related parameters on high-flow water three-way valve was determined. The results as follows： during the raising leg stage and early raising leg stage, when the damping ratio increases, the overshoot of system decreases and the setting time reduces, and the dynamic response performance has a significant improvement. During the loading stage and the overflow stage, the pressure in plunger chamber of single hydraulic prop, the output flow and the displacement of the high-flow water three-way valve decrease with the decreasing of the external load. The spring stiffness of the safety valve directs the flow and the spool＇s displacement of the safety valve, and it can be used to control the high-flow three-way valve＇s sensitivity.
文摘Objective A novel high-speed three-way solenoid valve is developed, which is used for the common-rail injection system equipped on DME powered engine. In order to improve the dynamic response performance of the three-way solenoid. Methods Experimental studies have been conducted to investigate the effects of spool stroke, drive voltage, negative demagnetizing pulse and two drive schemes on the dynamic response performance of the three-way solenoid valve. Results The results show that the dynamic response performance of the three-way solenoid valve can be remarkably improved by shortening the spool stroke and increasing the drive voltage. Simultaneously, the difference between the response time of closing valve and that of opening valve decreases. At each different drive voltage, there exists an optimal negative demagnetizing pulse corresponding to the same positive exciting pulse. At this optimal pulse, the dynamic response performance of the three-way solenoid valve is the best. In addition, the high drive voltage can lead to the smaller optimal negative demagnetizing pulse. It is also indicated from the experiments that the dynamic response performance of the three-way solenoid valve is better when the NO.1 drive scheme is adopted. The lower drive voltage results in the larger difference between the dynamic response performances for the two drive schemes. Conclusion The dynamic response performance of a novel three-way solenoid valve is good.
基金the National High Level Hospital Clinical Research Funding of the People's Republic of China(2022-GSP-GG-30).
文摘Objective:While evidence-based clinical guidelines recommend chordal-sparing mitral valve replacement,rather than mitral valve repair,in patients with severe ischemic mitral regurgitation(IMR)undergoing coronary artery bypass grafting,there are no similar recommendations for patients undergoing left ventricular reconstruction(LVR).This study aimed to compare the clinical outcomes of mitral valve repair and replacement in patients undergoing LVR complicated by more than moderate IMR.Methods:In this single-center cohort study,a total of 74 consecutive patients who underwent LVR and mitral valve surgery(repair group:59;replacement group:15),during the period from March 2000 to March 2021 at Fuwai Hospital(Beijing,China)were retrospectively enrolled.Survival rates were calculated with the Kaplan-Meier method and compared using the log-rank test.Univariate Cox analysis was performed to evaluate possible confounders,followed by adjustment in multivariate analysis.The primary outcome was survival free of major adverse cardiovascular and cerebrovascular events(MACCE).Results:Median follow-up time was 59.4 months.Compared with mitral valve replacement,mitral valve repair was associated with increased risk of perioperative use of ventricular assist device(22.0%vs.0,P=0.045).There was no difference in overall survival(hazard ratio(HR),1.10;95%confidence interval(CI),0.31-3.93;Plogrank=0.888)and MACCE-free survival(HR,1.54;95%CI,0.65-3.65;Plogrank=0.319),even after multivariate Cox regression(HR,1.35;95%CI,0.37-4.88;PCox=0.646;and HR,1.41;95%CI,0.57-3.44;PCox=0.455,respectively).Furthermore,while no differences were observed in ejection fraction and left ventricular end-diastolic diameter on follow-up echocardiography,mitral valve repair was associated with an increased risk of recurrent mitral regurgitation(P=0.041).Conclusions:In patients undergoing LVR complicated by more than moderate IMR,both concomitant mitral valve repair and replacement can be successfully achieved with comparable overall and MACCE-free survival outcomes;however,mitral valve replacement may be superior to mitral valve repair for persistent correction of mitral dysfunction.
