Pacemaker post transcatheter aortic valve replacement:A multifactorial risk?

Pacemaker post-transcatheter aortic valve replacement is related to multifactorial risk.Nwaedozie et al brought to the body of evidence electrocardiogram and clinical findings.However,procedural characteristics have at least as much impact on the final need for a permanent pacemaker and potentially on the pacing rate.In this regard,long-term follow-up and understanding of the impact of long-term stimulation is of utmost importance.

Predictors of permanent pacemaker implantation following transcatheter aortic valve replacement-the search is still on!

Several anatomical,demographic,clinical,electrocardiographic,procedural,and valve-related variables can be used to predict the probability of developing con-duction abnormalities after transcatheter aortic valve replacement(TAVR)that necessitate permanent pacemaker(PPM)implantation.These variables include calcifications around the device landing zone and in the mitral annulus;pre-existing electrocardiographic abnormalities such as left and right bundle branch blocks(BBB),first-and second-degree atrioventricular blocks,as well as bifas-cicular and trifascicular blocks;male sex;diabetes mellitus(DM);hypertension;history of atrial fibrillation;renal failure;dementia;and use of self-expanding valves.The current study supports existing literature by demonstrating that type 2 DM and baseline right BBB are significant predictors of PPM implantation post-TAVR.Regardless of the side of the BBB,this study demonstrated,for the first time,a linear association between the incidence of PPM implantation post-TAVR and every 20 ms increase in baseline QRS duration(above 100 ms).After a 1-year follow-up,patients who received PPM post-TAVR had a higher rate of hospital-ization for heart failure and nonfatal myocardial infarction.

Novel predictors of permanent pacemaker implantation following transcatheter aortic valve replacement

BACKGROUND Conduction and rhythm abnormalities requiring permanent pacemakers(PPM)are short-term complications following transcatheter aortic valve replacement(TAVR),and their clinical outcomes remain conflicting.Potential novel predictors of post-TAVR PPM,like QRS duration,QTc prolongation,and supraventricular arrhythmias,have been poorly studied.AIM To evaluate the effects of baseline nonspecific interventricular conduction delay and supraventricular arrhythmia on post-TAVR PPM requirement and determine the impact of PPM implantation on clinical outcomes.METHODS RESULTS Out of the 357 patients that met inclusion criteria,the mean age was 80 years,188(52.7%)were male,and 57(16%)had a PPM implantation.Baseline demographics,valve type,and cardiovascular risk factors were similar except for type II diabetes mellitus(DM),which was more prevalent in the PPM cohort(59.6%vs 40.7%;P=0.009).The PPM cohort had a significantly higher rate of pre-procedure right bundle branch block,prolonged QRS>120 ms,prolonged QTc>470 ms,and supraventricular arrhythmias.There was a consistently significant increase in the odds ratio(OR)of PPM implantation for every 20 ms increase in the QRS duration above 100 ms:QRS 101-120[OR:2.44;confidence intervals(CI):1.14-5.25;P=0.022],QRS 121-140(OR:3.25;CI:1.32-7.98;P=0.010),QRS 141-160(OR:6.98;CI:3.10-15.61;P<0.001).After model adjustment for baseline risk factors,the OR remained significant for type II DM(aOR:2.16;CI:1.18-3.94;P=0.012),QRS>120(aOR:2.18;CI:1.02-4.66;P=0.045)and marginally significant for supraventricular arrhythmias(aOR:1.82;CI:0.97-3.42;P=0.062).The PPM cohort had a higher adjusted OR of heart failure(HF)hospitalization(aOR:2.2;CI:1.1-4.3;P=0.022)and nonfatal myocardial infarction(MI)(aOR:3.9;CI:1.1-14;P=0.031)without any difference in mortality(aOR:1.1;CI:0.5-2.7;P=0.796)at one year.CONCLUSION Pre-TAVR type II DM and QRS duration>120,regardless of the presence of bundle branch blocks,are predictors of post-TAVR PPM.At 1-year post-TAVR,patients with PPM have higher odds of HF hospitalization and MI.

Cavitation of a Submerged Jet at the Spherical Valve Plate/Cylinder Block Interface for Axial Piston Pump

The spherical valve plate/cylinder block pair has the advantages of strong overturning resistance and large bearing area.However,the configurations of the unloading and pre-boosting triangular grooves on the spherical valve plate are different from those in the planar valve plate,resulting in special cavitation phenomenon on the spherical port plate pair.In order to study cavitation characteristics of spherical port plate pair,a dynamic CFD model of the piston pump including turbulence model,cavitation model and fluid compressibility is established.A detailed UDF compilation scheme is provided for modelling of the micron-sized spherical oil film mesh,which makes up for the lack of research on the meshing of the spherical oil film.In this paper,using CFD simulation tools,from the perspectives of pressure field,velocity field and gas volume fraction change,a detailed analysis of the transient evolution of the submerged cavitation jet in a axial piston pump with spherical valve plate is carried out.The study indicates the movement direction of the cavitation cloud cluster through the cloud image and the velocity vector direction of the observation point.The sharp decrease of velocity and gas volume fraction indicates the collapse phenomenon of bubbles on the part wall surface.These discoveries verify the special erosion effect in case of the spherical valve plate/cylinder block pair.The submerged cavitation jet generated by the unloading triangular grooves distributed on the spherical valve plate not only cause denudation of the inner wall surface of the valve plate,but also cause strong impact and denudation on the lower surface of the cylinder body.Finally,the direction of the unloading triangular groove was modified to extend the distance between it and the wall surface which can effectively alleviate the erosion effect.

Tribological Properties of Cylinder Block/Valve Plate Interface of Axial Piston Pump on the Tribometer

The tribological properties of cylinder block/valve plate is an important consideration in the design of axial piston pump.The effect of materials and heat treatment on friction and wear properties has been studied in depth.Engi-neering experiences show that the speed and load also affect the tribological properties,but these have not been systematically analyzed.The purpose of this paper is to evaluate the tribological properties of the commonly used materials(CuPb1 5Sn5 and 38CrMoAl/42CrMo)for cylinder block/valve plate with different heat treatment and con-tact pressure at different speed.During the test,tribometer is used to simulate the contact pattern between the valve plate/cylinder block in axial piston pump,the friction coefficient,wear rate and surface topography are analyzed to evaluate the tribological properties of different types of friction samples at different speed.Results indicate that:(1)contact surface of the samples at 1800 r/min is more prone to adhesive wear than those at 500 r/min;(2)in the terms of wear resistance,quench-tempered and nitrided 38CrMoAl(38CrMoAl QTN for short)is better than quench-tem-pered and nitrided 42CrMo,although they are all commonly used materials in the axial piston pump;(3)2.5 MPa is the critical contact pressure of the interface between valve plate made of 38CrMoAl QTN and cylinder block made of CuPb1 5Sn5 on the tribometer,which implies the pressure bearing area at the bottom of the cylinder block should be carefully designed;(4)the valve plate/cylinder block made of 38CrMoAl QTN/CuPb15Sn5 exhibits good tribological properties in a real axial piston pump.This research is useful for the failure analysis and structural optimization design of the valve plates/cylinder block.

A Case of Transient Advanced Atrioventricular Block after Aortic Valve Replacement, Report of a Case

Approximately 3%-11.8% of cases require permanent pacemaker implantation due to atrioventricular block (AVB) after aortic valve replacement (AVR), and determination of conduction disturbances such as left or right bundle branch block by preoperative electrocardiography is correlated with high risk postoperative permanent pacemaker implantation. Intraoperative risk factors include severe calcification of the aortic valve, prolonged cardiopulmonary bypass time, aortic clamp time. Recently, there have been reports of high rates of pacemaker implantation (14.2%) after transcatheter aortic valve implantation. The time of permanent pacemaker implantation after AVB is often 4-10 days, and the European Society of Cardiology guidelines recommend a period of seven days of persistent atrioventricular block postsurgery prior to permanent pacemaker implantation. We report a 79-year-old woman in which the patient developed high-degree AVB after AVR was performed for severe aortic stenosis with complete right bundle branch block. However, her pulse returned to sinus rhythm 7 days postsurgery.

Defective recovery of QT dispersion following transcatheter aortic valve implantation： frequency, predictors and prognosis

Background Corrected QT dispersion （cQTD） has been correlated with non-uniform ventricular repolarisation and increased mortality. In patients with aortic stenosis, cQTD has been shown improved after surgical valve replacement, but the effects of transcatheter aortic valve implantation （TAVI） are unknown. Therefore, we sought to explore the frequency, predictors and prognostic effects of defective cQTD recovery at 6 months after TAVI. Methods A total of 222 patients underwent TAVI with the Medtronic-CoreValve System between November 2005 and January 2012. Patients who were on class Ⅰ or Ⅲ antiarrhythmics or on chronic haemodialysis or who developed atrial fibrillation, a new bundle branch block or became pacemaker dependent after TAVI were excluded. As a result, pre-, post- and follow-up ECG （median： 6 months） analysis was available in 45 eligible patients. Defective cQTD recovery was defined as any progression beyond the baseline cQTD at 6 months. Results In the 45 patients, the mean cQTD was 47 ± 23 ms at baseline, 45 ±17 ms immediately after TAVI and 40 ± 16 ms at 6 months （15% reduction, P = 0.049）. Compared to baseline, cQTD at 6 months was improved in 60% of the patients whereas defective cQTD recovery was present in 40%. cQTD increase immediately after TAVI was an independent predictor of defective cQTD recovery at 6 months （per 10 ms increase; OR： 1.89, 95% CI： 1.15-3.12）. By univariable analysis, defective cQTD recovery was associated with late mortality （HR： 1.52, 95% CI： 1.05-2.17）. Conclusions Despite a gradual reduction ofcQTD after TAVI, 40% of the patients had defective recovery at 6 months which was associated with late mortality. More detailed ECG analysis after TAVI may help to avoid late death.

Conduction abnormalities after transcatheter aortic valve implantation

In the last few years, transcatheter aortic valve implantation （TAVI） has become an alternative procedure in patients with severe aortic stenosis and high risk for surgical aortic replacement. Due to the anatomic correlation between aortic valve structure and conduction system of the heart, one of the most common complications after TAVI is conduction system disturbances which including bundle branch block, complete heart block and need for permanent pacemaker implantation. Although these disturbances are usually not lethal, they may have a great influence on patients＇ state and long term-survival. Several risk factors for conduction disturbances have been identified which including age, anatomy of the heart, periprocedural factors, type of implanted valve, preexisting abnormalities and comorbidities. As this technique becomes more familiar to physicians, patients should be carefully screened for risk factors for the development of conduction abnormalities after TAVI in order to provide effective prevention and proper treatment.

胸肋间筋膜阻滞对心脏瓣膜置换术后早期恢复质量的影响

目的探讨胸肋间筋膜阻滞(PIFB)对心脏瓣膜置换术后早期恢复质量的影响。方法选择择期行正中切口心脏瓣膜置换术患者80例,男45例,女35例,年龄44~75岁,BMI 18~30 kg/m 2,ASAⅡ或Ⅲ级,随机分为两组:全麻联合PIFB组(P组)和全麻组(C组),每组40例。P组麻醉诱导后行双侧胸肋间筋膜平面阻滞,C组不行神经阻滞,术后均使用舒芬太尼静脉自控镇痛。采用15项恢复质量评分量表(QoR-15)评价术前24 h、术后24、72 h恢复情况,记录诱导前、切皮时、锯胸骨时、关胸时、出手术室时的HR和MAP,拔管后4、8、12 h静息和活动(咳嗽)时VAS疼痛评分。记录术中和术后48 h内舒芬太尼用量、拔管时间、重症监护病房(ICU)停留时间、术后首次肛门排气时间、术后住院时间,术后恶心呕吐、低血压、呼吸抑制等不良反应的发生情况和住院期间死亡情况。结果与C组比较,P组术后24、72 h QoR-15评分明显升高(P<0.05),拔管后4、8、12 h静息和活动时VAS疼痛评分明显降低(P<0.05),术中和术后48 h内舒芬太尼用量明显减少(P<0.05),拔管时间、术后首次肛门排气时间、ICU停留时间明显缩短(P<0.05),术后恶心呕吐发生率明显降低(P<0.05)。两组不同时点HR和MAP、术后住院时间、住院期间死亡率差异无统计学意义。P组未发生神经阻滞相关并发症。结论PIFB可以降低正中切口心脏瓣膜置换手术患者术后疼痛,提高术后恢复质量,促进术后康复。

基于SVM的干线输气管道泄漏压降速率信号识别

为解决压缩机抽吸或截断阀截断形成的压降信号导致截断阀发生误关断,以及小孔泄漏因管道压降不显著导致截断阀不动作的问题,以某输气干线为对象建立仿真模型,获取压缩机抽吸、截断阀紧急截断及管道泄漏3类不同工况下的300组压降信号,根据对点检测法计算出压降信号的压降速率值;以奇异值分解(SVD)法和极差归一化方法提取压降速率信号特征,采用支持向量机(SVM)法识别不同压降速率特征值信号,获取所对应的工况类型;针对SVM模型中的核函数参数与惩罚因子设置不合理,影响算法识别准确性的问题,采用教与学优化算法(TLBO)优化核函数参数与惩罚因子,建立干线输气管道泄漏信号智能识别的TLBO-SVM模型;应用该模型,分类识别该管道在3类工况下的300组模拟压降速率信号。结果表明:该模型对3类不同工况下压降速率信号的识别准确率为92.22%;对泄漏口径为50~125 mm,压降速率范围为0.01~0.07 MPa/min的小孔泄漏,识别准确率为96.67%。针对某干线管道的实际泄漏压降速率信号,TLBO-SVM识别到的准确率为100%。

液压排气阀特种卡帽注射模具设计与CAE分析

介绍了一种液压排气阀特种卡帽,内部采用异型卡位设计,外侧采用长尾柄结构,既有利于按压排气、也可以快速旋转,采用聚甲醛(poly for maldehyde, POM)材料,能保持较高的热稳定性和抗老化性能。在制造过程中,设计了一种全新的一模两腔的热流道哈弗块侧抽芯模具结构,经CAE分析产品的细节特征,在哈弗块上设置了隔水板冷却水路,内部型芯也设置了隔水板水路,提高了模具冷却效率,运用CAE软件模拟了产品的填充与冷却过程。经试模验证,该模具结构紧凑,塑件质量稳定、精度高,开合模动作合理可靠,制品顺利脱模,可有效节约成本,缩短了产品成型周期,提高了产品的生产率,产品能完全达到客户要求,为同类型产品提供了良好的解决方案。

基于VB的工业阀门应用程序设计

为了解决工业阀门设计过程中数据繁琐和精度低的问题,开发出一个基于VB语言6.0、Microsoft Access数据库和SQL语言的阀门设计的计算机应用程序。首先介绍了该程序的设计思想、功能和构成。然后着重介绍了数据库的建立、数据库的访问、数据的查询等关键技术。该程序实现了工业阀门设计的数据化、程序化。结果表明,该程序使阀门设计校核快速、准确、可视、存取方便,并且缩短了阀门开发周期,提高了工业阀门的可靠性和稳定性。

基于卷积注意力机制的阀门内漏声发射识别方法

阀门结构作为核电厂的关键设备部件之一,因长期处于高温高压环境下,其闸板或阀瓣易发生热变形或磨损导致密封不良,进而引发内漏事故。实时在线识别阀门的内漏状态,对提升核电机组热效率、提高阀门可靠性具有重要意义。因实际工业现场的基底噪声极易掩盖阀门内漏的声发射信号,进而造成阀门内漏状态的误判。为实现阀门内漏状态的快速准确识别,搭建了阀门内漏检测试验台架,开发了基于声发射方法的阀门内漏检测分析系统,将卷积注意力机制引入卷积神经网络中,实现高效快速地识别阀门内漏状态。结果表明,基于阀门内漏的声发射信号频域数据,利用卷积注意力机制神经网络能有效准确地识别阀门内漏状态,在内漏率为26 L/h时,识别准确率高达98%,并且具有较好的可靠性和鲁棒性。

输液设备用一次性使用防回流阀的阻断性能测试方法探究

对比了YY 0585.4—2009和ISO 8536-12:20212个标准中对输液设备用一次性使用防回流阀的阻断性能测试方法,分析了根据YY 0585.4—2009进行防回流阀阻断性能测试时的影响因素和可能存在的操作误区,指出了ISO 8536-12:2021中防回流阀阻断性能的测试方法更加完善合理、科学有效,为标准修订及检测人员的实际操作提供了借鉴和指引。

基于VB6.0的AutoCAD先导式截止阀设计软件开发

介绍了先导式截止阀的工作原理和优越性。重点阐述了以VB6.0为开发环境、运用ActiveX Autom ation提供的接口,实行AutoCAD的先导式截止阀专用软件二次开发的过程及关键步骤,探讨了阀门图形参数化设计和数据库建立的方法与途径,并给出了部分程序代码和例证,实践应用效果良好。

经导管主动脉瓣置换术后新发持续完全性左束支传导阻滞的危险因素及短期预后分析

目的 分析经导管主动脉瓣置换术(transcatheter aortic valve replacement, TAVR)术后新发持续完全性左束支传导阻滞(complete left bundle branch block, cLBBB)的相关危险因素及cLBBB对短期预后的影响。方法 选取2019年1月至2022年8月在青岛市市立医院心脏中心经股动脉行TAVR的78例主动脉瓣膜狭窄病人为研究对象,根据TAVR术后至出院时是否发生cLBBB分为新发持续性cLBBB组(n=26)和非左束支传导阻滞(LBBB)组(n=52)。收集并比较2组病人的基线资料、生化检查指标、CT等影像检查结果、瓣膜和手术相关数据,以及6个月后病人的预后情况。采用多因素Logistic回归分析TAVR术后新发持续性cLBBB的危险因素。结果 78例病人中,26例(33.3%)在TAVR术后出现持续性cLBBB。Logistic回归分析显示,术前存在的不完全性LBBB(OR=7.609, 95%CI:1.051~55.066)、植入瓣膜过大率≥17.25%(OR=1.096, 95%CI:1.017~1.181)及无窦侧瓣膜植入深度≥4.96 mm(OR=3.633, 95%CI:1.363~9.686)是TAVR术后新发持续性cLBBB的独立危险因素。术后第6个月随访时,新发持续性cLBBB组有更高的心力衰竭再住院率(16.0%比1.9%,P=0.02)。结论 术前不完全性LBBB、较高的植入瓣膜过大率及冠脉无窦侧瓣膜植入过深是影响TAVR术后持续性cLBBB发生的危险因素。新发cLBBB病人有更高的心力衰竭再住院风险。

Pressure Pulse Response of High Temperature Molten Salt Check Valve Hit by Crystal Particles

In view of the problem that crystalline particles cause wall vibration at a low temperature,based on two-phase flow model,computational fuid dynamics is used to conduct the numerical simulation of internal flows when the valve openings are 20%,60%and 100%respectively.The molten salt fow may be changed under strict conditions and produce forced vibration of the inner parts of molten salt particle shock valve body.Euler two-phase flow model is used for different molten salt sizes to extract temporal pressure pulse information and conduct statistical data processing analysis.The influence of the molten salt crystallization of molten salt particles on the fow and pressure pulse strength is analyzed.The results show that the crystallization of molten salt has a serious impact on the vibration of the valve body,especially in the throttle rate.The valve oscillation caused by the pressure pulsation mostly occurs from the small opening rate.As the opening increases,the pressure pulse threshold and its change trend decrease.

基于VB和SolidWorks的调节阀参数化设计

采用VB对SolidWorks2007进行二次开发,并将其应用于电动调节阀参数化设计,实现了调节阀零件的参数化建模,提高了设计效率。

井下清洁施工系统的研发与应用

针对临盘油田液压封隔器坐封过程中容易出现液压通道堵塞的问题,研发了清洁施工系统。该系统主要包括液压封隔器沉淀过滤装置和防堵型油套平衡阀两部分,具有结构简单、成本低廉、可靠耐用、适用性强、可重复使用、极易推广等特点。自2012年在临盘油田投入实际使用至今,平均每年应用80口井左右,均无液压通道堵塞问题。该系统已成为临盘油田Y445型液压封隔器封层施工必备辅助工具,并形成规范化的施工流程,带来了丰富的成果应用效益,可以在全国各油田液压封隔器施工中推广使用,具有广阔的应用前景。

特高压直流输电VBE装置故障闭锁分析及时序优化

特高压直流工程通常通过RTDS实时仿真技术对控制保护系统、换流阀阀基电子设备VBE装置的功能进行设计和验证。在某特高压直流工程RTDS试验系统对VBE装置断电试验过程中,出现了阀过流保护动作。为此结合故障时的闭锁时序,推导出换流阀触发异常,交流电源经由换流阀、旁通开关形成了两相短接导致阀过流保护动作的结论。最后,结合此类故障的特点,对闭锁时序进行了优化,并通过试验验证了优化后闭锁时序的有效性。