左前分支传导阻滞与心室肌传导障碍心电图研究:基于全心脏模型仿真（英文）

目的:探究左前分支传导阻滞与心室肌传导速度减慢的体表心电图之间相似之处,并探究其机理。创新点:通过心电图仿真,证明了左心室前壁传导速度减慢会形成类似左前分支阻滞的波形,并结合仿真心脏电兴奋传导时序,对其机理进行了合理解释。方法:将真实人体心脏通过64位螺旋计算机断层扫描(CT),进行心脏解剖结构建模。通过单域模型仿真出全心脏电兴奋的传导时序,然后利用边界元法计算出各时刻人体体表电位,进而计算出十二导联心电图。结论:左心室前壁心肌细胞传导速度的减慢,会形成类似左前分支阻滞的心电图波形,其主要区别是QRS波群的时间跨度以及幅度大小。     

窦性激动经房室结双径路前传双重激动心室致心动过速的电生理特点

目的:研究窦性冲动沿房室结双径路同时前传导致心动过速的电生理机制,探讨房室结快、慢径同时传导的影响因素。方法:56岁男性患者,室上性心动过速无休止发作,抗心律失常药物无效,心电生理检查明确心律失常性质,射频消融改良房室结。结果:心动过速时,记录食道电图P波后两个QRS波群呈P-QRS1-QRS2型;希氏束电图示A-H1-V1-H2-V2,心房激动沿双径同时前传时快径文氏或高度阻滞、慢径不典型文氏阻滞;心房内电生理刺激诱发出1∶2房室激动现象,呈S-A-H1-V1-H2-V2;快径不应期430 m s,慢径不应期260 m s;房室结区无室房逆传功能。P-P间期≤0.72 s,1∶2房室传导多见。射频消融改良慢径后,心动过速终止,房室传导为1∶1。随访3月未再发作心动过速,心脏结构与功能正常。结论:房室结双径路同时前传窦性冲动引起心动过速为非折返性心动过速。快/慢径前传不应期、传导时间差异及房室结区无室房逆传特性、窦性频率变化可能是窦性冲动能否同时沿双径路前传双重激动心室的影响因素。射频消融可根治此类心律失常。     

三个经典电生理实验刺激参数的设定

设置合适的刺激参数是电生理实验成功的重要前提.本文借助Pclab-430C生物医学信号采集处理系统,探究了"牛蛙坐骨神经干动作电位测定"、"牛蛙腓肠肌收缩特点"、"牛蛙心肌期外收缩与代偿间歇"三个经典电生理实验的阈刺激参数范围.结果表明:牛蛙坐骨神经干兴奋与腓肠肌兴奋的阈刺激强度差异不显著,而心肌产生兴奋需要的阈刺激比神经干和腓肠肌产生兴奋所需阈刺激强(p<0.01).心肌兴奋的最小阈刺激波幅(y)与波宽(x)符合y=2.766 9x-0.474(R2=0.936 5)关系.引起神经干兴奋及腓肠肌兴奋的电刺激基强度值均为(0.010±0.000)v;而引起心肌产生期外收缩的基强度值为(0.521±0.088)v.建议在蛙神经干动作电位和腓肠肌收缩特性实验中,将单刺激波宽设置在0.1~0.5 ms之间的一个值,波幅可从0.01 v逐渐增大;蛙心期外收缩实验中,建议将单刺激的波宽设置为1~5 ms之间的一个固定值,波幅从0.5 v逐渐增大.     

以坐标图辅助中学生理解细胞的生物电现象

笔者结合2013年生物高考大纲对”神经冲动的产生和传导”的要求,如何让中学生理解人体神经纤维的传导过程,帮助学生突破对细胞的静息电位、动作电位的产生机制和兴奋的传导机制的理解。     

“动物和人体生命活动的调节”考点透析

神经调节、体液调节和免疫调节共同调节动物和人体的生命活动,维持机体的稳态。生命活动的调节是高考常考内容之一。下面对此考点进行梳理和提炼。知识梳理一、神经调节的结构基础和基本方式1.神经元——神经系统的基本结构和功能单位(1)结构:细胞体和突起(包括树突和轴突)。(2)功能:接受刺激,产生兴奋,传导兴奋(能够传导的兴奋叫神经冲动)。2.反射——神经调节的基本方式(1)反射概念:在中枢神经系统的参与下,人体或动物体对内外环境变化作出的规律性     

基于FPGA的智能函数发生器的设计

介绍了一种基于FPGA的智能函数发生器的设计.采用EDA技术对此设计进行功能仿真和时序仿真,在EDA/SOPC系统开发平台上实现程序下载,同时在示波器上观察波形输出.结果表明采用该设计能够生成递增斜波、递减斜波、方波、三角波、正弦波及阶梯波等,并可以对频率进行调节,实现了信号发生器的功能.     

兴奋的传导和兴奋在细胞间的传递

1.兴奋在神经纤维上的传导 1.1细胞未受刺激处于静息状态时膜电位为外正内负的静息电位。可兴奋细胞受到有效刺激时产生动作电位,动作电位包括去极化和复极化两个阶段,动作电位在神经纤维上的顺序传播即神经冲动的传导。     

生物 动物和人体生命活动的调节

名师指要一、考查内容"动物和人体生命活动的调节"一直是高考的重点考查内容。在近几年的高考中,经常被考查的具体内容包括:1.反射弧的结构组成。包括反射弧图示的识别,反射弧各部分在反射中的作用和以反射弧为材料与实验相关的试题。2.神经细胞静息电位的产生和维持原因,神经细胞上兴奋产生的原理和传导原理,兴奋传导的原理。3.突触的结构,包括突触图示的识别。兴奋在突触间的传递过程和传递特点。     

奇妙的生物电

电大家都非常熟悉,如果有人告诉你,你的身体内有电流在流动,你或许会很惊讶吧？其实,生命过程的实质就是电子传递过程,特别是能量转换、神经传导、光合作用、呼吸过程均与此有关。电在生物体内普遍存在,被称为生物电。 一、生物电现象 人体心脏跳动、大脑思维、刺激反应均与生物电有关。心脏跳动时会产生1～2毫伏的电压,眼睛开闭产生5～6毫伏的电压,读书或思考问题时大脑产生0.2～1毫伏的电压。人体某一部位受到刺激后,感觉器官就会产生兴奋。兴奋沿着传入神经到达大脑,大脑便根据兴奋传来的信息发出指令;然后传出神经将大脑的指令传给相应的效应器官,从而产生相应的动作。这一过程传递的信息──兴奋,就是生物电。中医里经常提到的“通则不痛、痛则不通”,实质是指《黄帝内经》中提到的人体的十二正经及七经八脉,也就是经络。当我们的肌肉、骨骼、脏腑发生病变时,相关经络、穴位的生物电能、电阻就会发生改变。     

基于MATLAB仿真的模拟乘法器AM波分析

振幅调制(Amplitude Modulation,AM)是使载波的振幅按照所需传送信号的变化而变化,但频率保持不变的调制方法 .在AM调制电路中,要完成AM信号的低电平调制可采用频谱线性搬移电路来实现.其中实现方法分为二极管电路或利用模拟乘法器产生普通调幅波.基于对模拟信号幅度调制研究的目的,采用MATLAB仿真的方法绘制出调幅波频谱,分析幅度调制的波形和图像,以及如何利用模拟乘法器来产生普通调幅波,以此进一步了解振幅调制电路.通过仿真软件Multisim构建电路并进行仿真分析,改变电路参数分析调幅波波形,对调幅电路参数设计和实际工程应用具有重要作用.     

Clinical considerations of anticoagulation therapy for patients with atrial fibrillation

Atrial fibrillation (AF) increases the risk of stroke. New anticoagulation agents have recently provided alternative and promising approaches. This paper reviews the current state of anticoagulation therapy in AF patients, focusing on various clinical scenarios and on comparisons, where possible, between western and eastern populations.     

High accuracy in automatic detection of atrial fibrillation for Holter monitoring

Atrial fibrillation (AF) has been considered as a growing epidemiological problem in the world, with a substantial impact on morbidity and mortality. Ambulatory electrocardiography (e.g., Holter) monitoring is commonly used for AF diagnosis and therapy and the automated detection of AF is of great significance due to the vast amount of information provided. This study presents a combined method to achieve high accuracy in AF detection. Firstly, we detected the suspected transitions between AF and sinus rhythm using the delta RR interval distribution difference curve, which were then classified by a combination analysis of P wave and RR interval. The MIT-BIH AF database was used for algorithm validation and a high sensitivity and a high specificity (98.2% and 97.5%, respectively) were achieved. Further, we developed a dataset of 24-h paroxysmal AF Holter recordings (n=45) to evaluate the performance in clinical practice, which yielded satisfactory accuracy (sensitivity=96.3%, specificity=96.8%).     

Ultrasound ablation of pulmonary veins for treatment of paroxysmal atrial fibrillation

INTRODUCTIONMostparoxysmalatrialfibrillationisactivatedbyatrialectopiesoriginatinginthepulmonaryveins.Severalresearchesdemonstratedthatal most 50 %offocalatrialfibrillationoriginatesintheleftsuperiorpulmonaryveinandabout3 0 %intherightsuperiorpulmonaryvei…     

Ultrasound ablation of pulmonary veins for treatment of paroxysmal atrial fibrillation

Objective: to evaluate the efficacy and safety of ultrasound ablation of pulmonary veins for treatment of paroxysmal atrial fibrillation. Methods: The study population consisted of 9 patients with 5 males and 4 females enrolled consecutively who had idiopathic paroxysmal atrial fibrillation(AF). The ultrasound balloon was positioned through a special sheath to the orifice of the target vein by a transseptal procedure. The balloon was inflated with contrast-mixed saline (contrast: saline = 1:4) whose volume was decided by the diameter of the target pulmonary vein. The ablation energy was usually set up at 35 to 40 watts with temperature controlled at 60℃. The duration of each ablation was about 120 seconds which was repeated not over 10 times. Results: The average duration of the total procedure was 132±68 min for our patients. The average fluoroscopy time was 33±17 min. With a mean follow-up of 16±8 months after the procedure, AF was completely eliminated in 4 patients without antiarrhythmic drugs. The episodes of atrial fibrillation were eliminated in 2 patients with low dosage of oral amiodarone (0.1, once daily) which was ineffective before the procedure. The frequency of episodes was similar to that before the procedure in 3 patients. There were no complications such as hemopericardium, air embolism and stenosis of the pulmonary veins by angiography, related to the procedure. Conclusion: Ultrasound ablation of the pulmonary veins is a new approach to treat paroxysmal atrial fibrillation. Before we determined its value, we need to do more researches with bigger sample, randomization and comparison design.     

Current progress of computational modeling for guiding clinical atrial fibrillation ablation

Journal of Zhejiang University-SCIENCE B - Atrial fibrillation (AF) is one of the most common arrhythmias, associated with high morbidity, mortality, and healthcare costs, and it places a...     

Effect of corticosteroids on atrial fibrillation after catheter ablation: a meta-analysis

Objective

The purpose of this meta-analysis was to explore the effect of corticosteroids on atrial fibrillation (AF) following catheter ablation.

Methods

We searched PubMed, Embase, and the Cochrane Central Register of Controlled Trials for published articles describing the effect of corticosteroids in preventing AF recurrence after catheter ablation. Data on study and patient were extracted. Risk ratios (RRs) and 95% confidence intervals (CIs) were calculated by use of a random-effect model, and P values of <0.05 were considered significant.

Results

Two randomized controlled trials (RCTs) and three cohort studies involving 846 patients were included in this meta-analysis. Within one month of catheter ablation, corticosteroid use was associated with a declined risk of recurrence of AF in RCT (RR 0.57, 95% CI 0.39 to 0.85, P=0.005), but without significant effect in cohort studies (RR 1.01, 95% CI 0.79 to 1.30, P=0.94). After three months of catheter ablation, corticosteroids did not have a significant effect in the prevention of late recurrence of AF in either RCT (RR 0.78, 95% CI 0.38 to 1.59, P=0.49) or cohort studies (RR 0.96, 95% CI 0.70 to 1.31, P=0.78).

Conclusions

Our meta-analysis suggested that periprocedural administration of corticosteroids of catheter ablation was associated with reduction of early but not late recurrence of AF.

     

Metabolic benefits of rivaroxaban in non-valvular atrial fibrillation patients after radiofrequency catheter ablation

Background and objective

Rivaroxaban is a new oral anticoagulant for stroke prevention in patients with non-valvular atrial fibrillation (NVAF), which has less drug–food interaction than warfarin. We conducted this prospective randomized study to evaluate the metabolic benefits as well as the safety and efficacy with rivaroxaban versus warfarin in patients with NVAF following radiofrequency catheter ablation (RFCA).

Methods

From April to July 2014, 60 patients with NVAF undergoing RFCA were prospectively enrolled in our study. Following RFCA, all patients were randomly assigned to receive rivaroxaban (Group R, n=30) or warfarin (Group W, n=30). Metabolic indices including serum total protein, albumin, globulin, and high-density lipoprotein (HDL) as well as bleeding, stroke, and systemic thromboembolism events were evaluated and compared during follow-up after 15, 30, 60, and 90 d of RFCA procedure.

Results

Serum total protein, albumin, globulin, and HDL levels were all significantly elevated at each follow-up stage in Group R when compared to the baseline (P<0.05 respectively). In Group W, the metabolic indices decreased at first and then had an increasing trend. There were no deaths or thromboembolic complications in each group. The prevalence of total bleeding complications was similar between Group R and Group W (11/30, 36.7% vs. 10/30, 33.3%, P=0.79).

Conclusions

Patients with NVAF receiving rivaroxaban after RFCA procedures appear to benefit from a metabolic perspective compared with warfarin, providing practical clinical reference for the choice of the anticoagulant. Rivaroxaban seems to be as safe and effective in preventing thromboembolic events as warfarin for these patients.

     

血脂对老年慢性心房颤动患者缺血性中风的影响

目的探讨血脂对老年慢性心房颤动(chronic atrial fibrillation,CAF)患者发生缺血性中风的影响.方法对资料完整的182例老年(＞60岁)CAF患者进行前瞻性研究,分析血脂与缺血性中风的关系.结果老年CAF患者血清胆固醇和甘油三酯增高、高密度脂蛋白降低与缺血性中风有明显关系(P＜0.05),其中胆固醇增高与缺血性中风关系最显著(P＜0.001).结论血脂异常是老年CAF患者发生缺血性中风的重要危险因素.     

Simulation of biatrial conduction via different pathways during sinus rhythm with a detailed human atrial model

In order to better understand biatrial conduction, investigate various conduction pathways, and compare the differences between isotropic and anisotropic conductions in human atria, we present a simulation study of biatrial conduction with known/assumed conduction pathways using a recently developed human atrial model. In addition to known pathways: (1) Bachmann’s bundle (BB), (2) limbus of fossa ovalis (LFO), and (3) coronary sinus (CS), we also hypothesize that there exist two fast conduction bundles that connect the crista terminalis (CT), LFO, and CS. Our simulation demonstrates that use of these fast conduction bundles results in a conduction pattern consistent with experimental data. The comparison of isotropic and anisotropoic conductions in the BB case showed that the atrial working muscles had small effect on conduction time and conduction speed, although the conductivities assigned in anisotropic conduction were two to four times higher than the isotropic conduction. In conclusion, we suggest that the hypothesized intercaval bundles play a significant role in the biatrial conduction and that myofiber orientation has larger effects on the conduction system than the atrial working muscles. This study presents readers with new insights into human atrial conduction.     

Segmental radiofrequency ablation of pulmonary vein ostia for patients with refractory paroxysmal atrial fibrillation using multi-slice spiral computed tomography guidance

INTRODUCTION Pulmonary veins(PV)may play an importantrole in both the initiation and maintenance of parox-ysmal atrial fibrillation(AF)(Fynn and Kalman,2004).Curative treatment of patients with paroxys-mal AF is possible by radiofrequency ablation,mak-ing segmental or linear lesions around the ostia ofPVs using a3-dimentional mapping system(Carto)(Pappone et al.,2000;2001;Oral et al.,2003).Multi-slice spiral computed tomography(MSCT)could generate a3-dimentional image of left atrium…