糖尿病兔心房电机械功能受损与心房颤动的关系

目的 应用组织多普勒超声心动图(DTE)评价四氧嘧啶诱导的糖尿病兔心房电机械功能,同时观察心房病理、电生理改变及心房颤动(房颤)易感性的变化.方法 应用四氧嘧啶诱导成功糖尿病兔共8只,健康对照组8只,饲养8周,应用DTE测定心电图P波开始至心房各节段速度曲线上舒张晚期a'波开始的时间间期(Pastart)及心电图P波开始至DTE速度曲线上舒张晚期a＇波峰值处的时间间期( Papeak);建立Langendorff灌流的离体兔心脏模型,测量心房间传导时间(IACT)、心房各点有效不应期(AERP)、AERP的离散度(AERPD)、应用短阵快速刺激观察房颤诱发情况,应用天狼猩红染色评价左心房纤维化情况.结果 与对照组比较,糖尿病组兔左心房前后径明显增大[(6.8±0.6)mm对(8.3±0.6)mm,P＜0.01],室间隔增厚[(1.9±0.2)mm对(3.0±0.5) mm,P＜0.01];左心房侧壁Pastart及右心房Pastart延长[分别为(40.5±12.9) ms对(60.4±20.4) ms,P＜0.05;(59.8±20.1)ms对(83.0±11.0)ms,P＜0.05)];IACT延长[(37.6±8.9) ms对(27.7±2.1) ms,P＜0.01)],房颤诱发率升高(6/8对1/8,P＜0.05);病理检查提示糖尿病组左心房心肌间质明显纤维化.两组房间隔处Pastart,左心房后壁Pastart及Papeak均与IACT显著相关.结论 糖尿病兔心房电机械功能受损,与心房肌纤维化、心房间电传导延迟有关,可能是糖尿病发生房颤的机制之一.     

心房重构--未来心房颤动防治的新靶点

心房重构是心房颤动 (Af)发生和自我持续的核心环节 ,包括电重构、收缩功能重构和结构重构三种形式。以Af作为靶点可能是将来Af治疗的根本性策略。本文综述了该领域研究的最新进展。     

复律后左心房功能恢复与心房颤动持续时间相关性的临床研究

目的:应用心肌组织多普勒技术结合M型超声、脉冲血流多普勒和心尖搏动图评价心房颤动(房颤)复律后心房功能的变化及其相关因素。方法:正常对照组20例,房颤复律患者34例。根据房颤持续时间分成短期房颤组(n=18)和长期房颤组(n=16),于复律后1小时、1天、1周和1个月行超声检查。采用心肌组织多普勒技术测量二尖瓣环侧壁心房收缩期心肌组织运动峰速(Am)和舒张早期运动峰速(Em)并计算Am/Em比值,M型超声测量瓣环侧壁舒张晚期心肌最大运动幅度(DAD)和舒张早期最大运动幅度(DED)并计算DAD/DED比值,脉冲血流多普勒测量心房收缩期跨瓣血流最大流速(A)和心室舒张早期血流最大流速(E)并计算A/E比值,心尖搏动图记录心房收缩压力波。并筛选出与复律后1小时、1天、1周左心房心肌组织运动速度有关的临床变量。结果:复律后1小时、1天、1周与Am相关的临床变量均为房颤持续时间。左心房功能与房颤持续时间的关系:复律后1小时及1天,Am、Am/Em,A/E,DAD、DAD/DED在两房颤组均低于正常对照组(P<0.05);长期房颤组低于短期房颤组(P<0.05);复律后1周,长期房颤组仍低于正常对照组和短期房颤组(P<0.05);短期房颤组与正常对照组无差异(P>0.05)。复律后1个月,除长期房颤组DAD/DED仍低于正常对照组(P<0.05),其余指标3组间无差异(P>0.05)。复律后左心房顿抑仅发生于长期房颤组,其发生率于1小时为43.8%,1天为25%,1周为12.5%。结论:房颤复律后左心房功能的恢复及左心房顿抑的发生与房颤持续时间有明显相关性。     

Partial atrial standstill: a case report

Twelve-lead electrocardiograms revealed no atrial activity and a wide QRS escape rhythm at 38 beats/min in a 20-year-old man who presented with syncope. Doppler echocardiography documented the absence of A wave both in the tricuspid and mitral valve flow. The only mechanical activity was documented at the left atrial appendage. An electrophysiologic study demonstrated electrical inactivity in the right atrium and an atrial tachycardia in the left atrium. Atrial pacing with maximum output did not capture the atria. Our case represents an advanced stage of partial atrial standstill, with a mechanical and electrical atrial activity confined only to the left trial appendage. The patient remained asymptomatic after receiving a VVIR pacemaker and anticoagulation therapy.     

The interrelationship between atrial fibrillation and atrial flutter

For a long time, it has been known that atrial fibrillation and atrial flutter have a close clinical interrelationship. Recent electrophysiological studies, especially mapping studies, have significantly advanced our understanding of this interrelationship. Regarding the relationship of atrial fibrillation with atrial flutter: Atrial fibrillation of variable duration precedes the onset of atrial flutter in almost all instances. During the atrial fibrillation, the functional components needed to complete the atrial flutter reentrant circuit, principally a line of block between the venae cavae, are formed. If this line of block does not form, classical atrial flutter does not develop. If this line of block shortens or disappears, classical atrial flutter disappears. In fact, it is fair to say that the major determinant of whether atrial fibrillation persists or classical atrial flutter develops is whether a line of block forms between the venae cavae. Regarding the relationship of atrial flutter with atrial fibrillation: Studies in experimental models and now in patients have demonstrated that a driver (a rapidly firing focus or a reentrant circuit of very short cycle length) can cause atrial fibrillation by producing fibrillatory conduction to the rest of the atria. When the driver is a stable reentrant circuit of very short cycle length, it is, in effect, a very fast form of atrial flutter. There probably is a spectrum of reentrant circuits of short cycle length, i.e., "atrial flutter," that depend, in part, on where the reentrant circuit is located. When the cycle length of the reentrant circuit is so short that it will only activate small portions of the atria in a 1:1 manner, the rest of the atria will be activated rapidly but irregularly, i.e., via fibrillatory conduction, resulting in atrial fibrillation. In short, there are probably several mechanisms of atrial fibrillation, one of which is due to a very rapid atrial flutter circuit causing fibrillatory conduction. In sum, atrial fibrillation and atrial flutter have an important interrelationship.     

房颤与房扑的射频消融治疗研究

目的 探讨房颤与房扑之间的相互关系，寻找房颤的射频治疗方法。方法 对40例阵发性房颤患者进行了电生理标测及射频消融。结果 40例中有6例患者发生房扑，行右房峡部消融，1例行Halo电极标测示峡部双向阻滞，随访12－30个月房颤消失或次数明显减少。结论 房颤与房扑为两种密切相关的心律失常，消融右房峡部可能对部分房颤患者起到治疗作用。     

腹主动脉结扎大鼠房性快速心律失常诱发率升高

研究腹主动脉结扎大鼠心房颤动 (AF)和房性心动过速 (AT)诱发率的改变。雄性SD大鼠随机分为非手术对照组 (C组 ,n =1 2 ) ,腹主动脉结扎组 (AB组 ,n =1 2 )和腹主动脉结扎 +依那普利组 (AB E组 ,n =1 2 ) ,C组和AB组按常规方法喂养 ,AB E组于术后第 2天加喂依那普利 (2 0mg/Kg ,放于饮水中 ) ,三组喂养时间均为 4周。 4周后动物麻醉 ,描记I导体表心电图 ,经左侧颈总动脉插管测量收缩压和舒张压。在心脏体外灌流条件下 ,采用心房短阵刺激评价房间传导时间 (IACT)和心房对刺激的反应。取心房组织制作切片 ,Masson染色 ,测量纤维组织占总区域的百分比。结果 :AB组AngⅡ水平较C组明显升高 (1 .76± 0 .5ng/mlvs 0 .97± 0 .4ng/ml,P <0 .0 1 ) ,P波持续时间和IACT也较C组延长 (分别为 2 7.8±5 .1msvs2 3± 4 .5ms,P <0 .0 5和 37.3±5msvs 2 3.1± 3.3ms,P <0 .0 1 ) ,在AB组诱发出 4例AF和 3例AT ;AB E组AngⅡ水平较AB组明显降低 (1 .1 2± 0 .3ng/mlvs 1 .76± 0 .5ng/ml,P <0 .0 5 ) ,P波持续时间和IACT也较AB组缩短 (分别为 2 2± 4 .1msvs 2 7.8± 5 .1ms ,P <0 .0 5和 2 2 .6± 3msvs 37.3± 5ms,P <0 .0 1 ) ,仅诱发出 2例AT ;C组没能诱发出AF和AT。组织学发现AB组较C组有明显的纤维化 ,AB E组纤维?     

快速起搏心房对犬心房电生理特性改变的研究

目的:研究心房颤动时心房肌的电生理改变。方法:快速持续起搏犬右心房24h制作房颤模型。比较起搏前(P0)、起搏后6h(P6)、12h(P12)和24h(P24)各时段的血压、心房传导速度和房颤波周长(atrial fibrillation cycle length,AFCL)的变化来分析心房肌的电生理改变。结果:起搏后平均动脉血压在P12[(126.06±7.01)mmHg]和P24时[(118.56±8.26)mmHg]较P0[(138.23±5.42)mmHg]明显下降。起搏24h后,P波时间是(78.91±6.21)ms,PA间期是(94±7.89)ms,与起搏前比较有显著延长(P<0.05)。连续快速起搏右心房在P6、P12和P24时的房颤自发维持的时间分别是5~10s、3~5min和15~20min。在起搏前和起搏后不同时间段,左房AFCL明显短于右房AFCL。右房房颤自发持续时间5~10s和15~20min的AFCL分别是(131.86±5.32)ms和(112.45±5.27)ms,P<0.05;左房房颤自发持续时间5~10s和15~20min的AFCL分别是(99.53±4.96)ms和(84.31±2.84)ms,P<0.05。结论:快速心房起搏建立的房颤模型可引起血压进行性下降、心房传导速度减慢和AFCL缩短。     

Ibutilide转复心房颤动的Meta分析

应用Meta分析的方法评价静脉使用Ibutilide转复心房颤动 (简称房颤 )和 (或 )心房扑动 (简称房扑 )的疗效及副作用。检索公开发表的英文及中文相关文献 ,并建立数据库 ,应用Meta统计分析方法 ,按观察时间、给药方法、房颤、房扑类型等对数据进行综合分析。共 16项试验 15 13例患者入选本研究。经统计 ,静脉推注Ibutilide能有效转复房颤或房扑 ,2 0 ,30 ,6 0min转复率分别为 14.9%、2 1.2 %、33.7% ,90min总转复率为 38.4% ,且房扑转复疗效优于房颤 (转复率差 2 4.5 % ,P <0 .0 0 1)。Ibutilide转复房颤、房扑与安慰剂相比的疗效率差在 2 0 ,6 0 ,90min分别为16 .1%、30 .4%及 38.7% (P <0 .0 0 1)。主要副作用为用药早期出现多型性室性心动过速 ,多在静脉推注药物后 40min内发生。结论 :Ibutilide能有效转复房扑及房颤 ,但须在严格监控下进行。     

Atrial fibrillatory rate and sinus rhythm maintenance in patients undergoing cardioversion of persistent atrial fibrillation.

AIMS: The study set out to explore whether an index of atrial electrical electrophysiology can be used to predict atrial fibrillation (AF) relapse, and if the predictive properties differ as a result of arrhythmia duration. METHODS AND RESULTS: The study comprised 175 consecutive patients with persistent AF (median duration 94 days, range 2 to 1044) referred for cardioversion. Twenty-nine patients had arrhythmia duration under 30 days (median 5 days, range 2-26). Atrial fibrillatory rate (AFR) was estimated using a frequency power spectrum analysis of QRST-cancelled ECG. At 1-month follow-up, 56% of the patients had relapsed to AF. The pre-cardioversion mean AFR of those patients was 399+/-52 fibrillations per minute (fpm) compared with 363+/-63 fpm among patients maintaining SR (P<0.0001). In patients with short AF duration, the difference was even more pronounced (424+/-52 vs. 345+/-65 fpm, P<0.01). In this group, a finding of an AFR above the mean value of the study population predicted AF relapse with high accuracy. CONCLUSION: In patients undergoing cardioversion of persistent AF, AF relapse is predicted by a higher AFR. A stronger association is seen in patients with short arrhythmia duration, reflecting either rapid remodelling or pre-existing changes in those who relapse to AF.     

长短周期现象与心房颤动和心房扑动

为了解心房颤动及心房扑动发生时的长短周期现象的临床意义,观察经动态心电图或监测心电图证实的心房颤动８例和心房扑动６例。结果显示：心房颤动或心房扑动发生前的长周期多见于房性期前收缩后代偿间歇及明显窦性心动过缓等心律失常;长短周期现象对心房颤动,心房扑动的启动作用可经心脏的程度刺激诱发和复制;６例患者经ＤＤＤ起搏治疗,陈发性心房颤动及心房扑动的发生率明显下降,部分病例还需服用抗心律失常药物。认为长短周     

Impact of Closed-Loop Stimulation, overdrive pacing, DDDR pacing mode on atrial tachyarrhythmia burden in Brady-Tachy Syndrome. A randomized study.

AIMS: Atrial overdrive pacing algorithms increase Atrial Pacing Percentage (APP) to reduce Atrial Tachyarrhythmia (AT) recurrences in patients with Brady-Tachy Syndrome (BTS). This study aimed to compare AT burden and APP in BTS patients treated with conventional DDDR pacing, DDD+ overdrive or Closed-Loop Stimulation (CLS). METHODS AND RESULTS: One hundred and forty-nine BTS patients were included (72 male, mean age 74+/-9), who received a dual chamber pacemaker (Philos DR or Inos 2+CLS, Biotronik GmbH, Berlin, Germany) programmed in DDD at 70min(-1). At 1-month follow-up, DDDR, DDD+ or CLS algorithms were activated according to randomization. Follow-up visits for data collection were performed at 4 and 7 months. Non parametric statistical tests (Kruskal-Wallis H-test, Dunn test, Spearman coefficient) were used to analyse not-normally-distributed samples. At 7 months, AT burden was significantly lower in CLS group (20.3+/-63.1min/day, P<0.01) compared to DDDR (56.0+/-184.0min/day) and DDD+ group (63.1+/-113.8min/day). APP was higher in CLS (89.0+/-13.2%) and in DDD+ group (97.9+/-2.7%) than in DDDR group (71.1+/-26.7%, P<0.001). The correlation found between AT burden and APP was very weak: at 7-month follow-up the Spearman coefficient was -0.29 (P=NS) in CLS, -0.52 (P<0.01) in DDD+, -0.22 (P=NS) in DDDR. CONCLUSIONS: CLS pacing was associated with a significantly lower AT burden,compared to the other pacing algorithms. Moreover APP was significantly higher in DDD+ and in CLS mode, than in DDDR. APP weakly correlated with AT burden only in DDD+ mode, though the lowest AT burden level was obtained in the CLS group where no significant correlation was found.     

The left atrial function index: a rhythm independent marker of atrial function.

AIMS: This study evaluates a simple echocardiographic rhythm independent expression of left atrial (LA) function, 'the left atrial function index' (LAFI). BACKGROUND: Quantitation of LA function is challenging and often established parameters including peak A are limited to sinus rhythm (SR). We hypothesized that atrial function could be characterized independent of rhythm by combining analogues of LA volume, reservoir function and LV stroke volume. METHODS: Seventy-two patients with chronic atrial fibrillation (CAF) were followed for six months post cardioversion (CV). Thirty-seven age matched healthy subjects were controls. The LAFI = LAEF x LVOT-VTI/LAESVI (LAEF = LA emptying fraction, LAESVI = maximal LA volume indexed to BSA, LVOT-VTI = outflow tract velocity time integral). RESULTS: The LAFI pre-CV in the CAF group was depressed vs controls (0.10 +/- 0.05 vs 0.54 +/- 0.17; P = 0.0001). Post-CV, LAFI was lower in persistent AF than in those restored to SR (AF vs SR: 0.08 +/- 0.03 vs 0.15 +/- 0.08; P = 0.0001), improved progressively in SR and was unchanged when AF persisted. CONCLUSION: The LAFI, a simple, rhythm independent expression of atrial function, appears sensitive to differences between individuals in AF and those restored to SR and justifies clinical and investigative applications.     

Criteria for the electrocardiographic diagnosis of atrial flutter improve diagnostic accuracy

Purpose

We previously developed and validated diagnostic criteria for the differentiation of atrial flutter from atrial fibrillation. In this study we examine if the criteria (F waves in the frontal plane and a partially or completely regular ventricular response) can improve the diagnostic accuracy of internists.

Methods

Two groups of 10 internists (1 group given the criteria and 1 not) read a set of electrocardiograms (ECGs) selected from the hospital database with cardiologist-confirmed diagnoses of atrial fibrillation, atrial flutter, or “atrial fibrillation-flutter” (100 each). The final diagnoses of all ECGs were provided by a consensus of electrophysiologists. The criteria also were used to establish the criteria-based diagnoses.

Results

Of the 298 ECGs analyzed, the electrophysiologist diagnosis was atrial fibrillation in 71% and atrial flutter in 29%. The concordance of the internists’ diagnoses with the electrophysiologist consensus diagnoses was 66 ± 12% for those not given the criteria and 81 ± 4% (P <.01) for those given the criteria. The concordance of the internists’ diagnoses with the criteria based diagnoses was 66 ± 12% for those not given the criteria and 83 ± 4% (P <.01) for those given the criteria.

Conclusions

The simple criteria of F waves in the frontal plane and a partially or completely regular ventricular response can be used to improve the differentiation of atrial flutter from atrial fibrillation based on the ECG.