健康人微伏级T波电交替试验检测分析

微伏级T波电交替 (MTWA)与器质性心脏病恶性室性心律失常的发生密切相关。T波电交替偶见于正常人运动时。本研究的目的是探讨正常人静息和运动时MTWA的发生情况。用CambridgeHeart.HeartwaveTMsys tem心脏诊断系统 ,以频谱法检测 4 5例健康志愿者MTWA。结果 :所有受试者静息时MTWA阴性。运动负荷试验时 ,非持续性MTWA 5例 (11.11% ) ,持续性MTWA 2例 (4.4 4 % ) ,1例阈值心率 <110次 /分 ,另一例发作心率>110次 /分。 4 5例中 ,MTWA阳性 1例 (2 .2 2 % ) ,但持续时间短暂 (1min) ,不确定性 2例 (4.4 4 % ) ,阴性 4 2例(93.33% )。结论 :健康人MTWA阳性发生率低 (2 .2 2 % ) ,短暂的MTWA无恶性室性心律失常的临床意义。     

微伏级T波电交替及其对心脏性猝死的预测价值

微伏级T波电交替(MTWA)是指普通心电图不能发现的需经特殊的、心电信号处理技术才能记录的T波电交替。其发生机制尚不明确,可能与心肌细胞复极的非均一性、离子通道异常和交感活性增加等有关,检测方法有频域法及时域法。MTWA检测能否准确筛选出致死性心律失常的低危患者尚不确定,大多数的临床试验表明,MTWA预测缺血性心脏病、扩张型心肌病和心力衰竭及高血压患者心律失常事件的灵敏度和阴性预测价值较高,而对肥厚型心肌病、遗传性离子通道疾病的应用价值尚需进一步评价。     

微伏级T波电交替的临床应用研究进展

微伏级T波电交替(MTWA)是指T波形态、幅度、极性在微伏级水平发生规律变化,是一个有希望的心源性猝死危险分层的无创方法。MTWA判断标准:①阳性:踏车运动,心率110次/分时T波交替幅度1.9μV且持续1 min以上,交替率3;②阴性:不符合阳性标准,心率≥110次/分时持续1 min无明显的交替,噪音引起记录不清晰,以及10%房(室)性早搏;③不能确定:≥10%房(室)性早搏、房室结文氏现象和噪音引起的过多干扰。MTWA主要用于筛选植入ICD一级预防的患者,MTWA阴性预测价值高,阳性或不能确定时需联合左室射血分数或电生理检查结果综合判断。     

健康人Holter微伏级T波电交替值分析

目的探讨健康体检者基于Holter分析系统时域法检测微伏级T波电交替(microvolt T wave alternans,MT-WA)的正常参考值。方法 112例健康体检者接受Holter检查,移动平均修正法连续检测微伏级T波电交替,采集最大MTWA值,不同心率及不同时间段MTWA值,分析交替压(alternans voltage,Vlat)的大小、分布及其与性别、时间、心率及导联的关系。结果 (1)最大MTWA百分位数P75参考值MV5<66μV、MaVF<70μV、MV1<79μV;Valt与性别无关;最大MTWA发生时的心率与24小时平均心率有相关性(r=0.87,P<0.05)。(2)Holter-MTWA数据呈偏态分布,在三个时间段各导联MTWA百分位数P75值均≤5μV;上午10~12时最高,夜间2~4时最低;MV5与MaVF导联MTWA值无显著差异,MV1导联MTWA值最高。结论健康体检者MTWA值呈动态变化,可能与自主神经调节有关;Holter-MTWA检测技术便于在临床研究实践中应用。     

国人微伏级T波电交替试验正常参考值探讨

目的　探讨国人微伏级T波电交替 (microvoltTwavealternanstest,MTWA)试验的正常参考值。方法　频谱法检测 4 4例健康志愿者微伏级T波电交替 ,分析交替压 (alternansvoltage ,Valt)的大小及其与性别、心率 (HR)的关系。结果　 (1)正常中青年国人T波电交替压大小与性别无关 (P >0 0 5 )。 (2 )HR <90 /min时 ,Valt均值 <1 0 μV ,95 %可信区间 0 4 5～ 1 0 2 μV ;90 /min≤HR≤ 110 /min时 ,Valt均值 <1 9μV ,95 %可信区间 1 4 7～ 2 0 8μV ;HR>110 /min时 ,Valt可 >1 9μV ,95 %可信区间 1 5 2～ 2 4 1μV。各组间比较 ,Valt差异有非常显著性意义 (P均 <0 0 1)。尤以综合导联及胸前导联差异有显著性 (P均 <0 0 1)。 (3)随心率增加 ,交替压增大 ,心率与综合导联Valt有相关性 (r=0 4 94 ,P <0 0 1)。结论　微伏级T波电交替具有频率依赖性。运动试验方案测定T波电交替 ,正常中青年国人 90 /min≤HR≤ 110 /min时 ,正交导联及综合导联Valt<1 9μV ,胸前导联Valt<2 0 μV。     

急性心肌梗死后患者不同时间的微伏级T波电交替

目的观察急性心肌梗死(简称心梗)后不同时间的微伏级T波电交替(MTWA)。方法用带有TWA移动平均修正技术(TWA MMA)的动态心电图检测系统,以时域法检测45例急性心梗后患者小于1个月、6个月时MTWA。判断标准是:在V3导联Val≥t47μV为阳性,Val≤t47μV为阴性。2次检测均为阴性的归为A组;2次检测,其中1次为阳性的归为B组。结果小于1个月时MTWA阴性占80%,阳性占20%;6个月时MTWA阴性占60%,阳性占40%;6个月时有11例(24.4%)MTWA由阴性转变为阳性,有3例(6.7%)由阳性转变为阴性。这两个时期检测MTWA,结果一致的病人有29例,符合率为64.4%。阴性转阳性患者左室射血分数降低多于持续阴性患者。结论急性心梗后6个月内MTWA处于动态变化之中,对急性心梗后6个月内,MTWA阴性的患者应予更多的关注。     

糖尿病对微伏级T波电交替影响的临床分析

目的 T波电交替(TWA)是心肌梗死后、缺血性心肌病、心力衰竭等患者发生心脏性猝死(SCD)的独立预测因子。相关研究报道糖尿病患者发生SCD的风险增加,但缺乏数据表明糖尿病患者微伏级T波电交替(microvoltT-Wave Alternans,MTWA)异常比例增加,本试验主要探讨糖尿病是否使MTWA异常的比例增高。方法选择自2000年1月至2011年5月兰州大学第一医院内科198例行平板运动试验的患者,分为A组:对照组,B组:糖尿病组,C组:冠心病组,D组:糖尿病合并冠心病组。用Logistic回归法对纳入患者MTWA与疾病相关性进行分析,并进一步分析糖尿病患者MTWA异常比例增高与血糖控制水平及病史的相关性。结果 Logistic回归显示异常MTWA与冠心病相关(p<0.001,OR=4.91,95%CI:2.52-9.55),与糖尿病相关(p=0.008,OR=2.39,95%CI:1.26-4.53)。对糖尿病患者进行Logistic回归显示MTWA异常仅与糖化血红蛋白相关(p=0.02,OR=6.00,95%CI:1.37-26.24),与糖尿病病史长短无关。结论 2型糖尿病患者中异常MTWA常见,异常比例为23.40%,MTWA异常比例增加与血糖控制水平具有相关性。     

平板运动试验检测微伏级T波电交替的研究

目的观察微伏级T波电交替、平板运动试验结果、经心率校正的QT间期(QTc)和室性心律失常发生的关系,为临床判断患者病情和预后提供参考。方法选择我院内科2011年8月至2012年7月行平板运动试验的患者260例,其中男性140例,女性120例,采用GE公司提供的MarquetteT波电交替(TWA)分析程序,进行标准时域运动试验,最后对每例患者的性别、年龄、TET、MTWA、QTC等指标进行分析。结果 260例患者中TET阳性86例,TET阴性174例,TWA阳性42例,TWA阴性219例,所有病例中发生室性心律失常59例,QTc延长142例,双水平logistic回归分析显示TET阳性者发生室性心律失常的风险增加2.37倍(p=0.018,95%可信区间1.163~4.841);MTWA阳性者发生室性心律失常的风险增加7.213倍(p=0.000,95%可信区间3.178~16.372);男性较女性更易出现室性心律失常(OR值2.239,p=0.020,95%可信区间1.135~4.418)。结论 TET和MTWA阳性者发生室性心律失常的风险显著增加,男性患者更容易发生室性心律失常,临床上对怀疑有冠心病的男性患者应该积极进行TET和MTWA检测,以尽早发现高危患者并给予相应的干预措施。     

微伏级T波电交替与急性心肌梗死患者恶性心律失常的相关性研究

目的评估微伏级T波电交替与急性心肌梗死(AMI)患者恶性心律失常的相关性。方法入选89例AMI患者,并根据住院期间是否发生恶性心律失常分为恶性心律失常亚组及无恶性心律失常亚组,另选来我院健康体检的非心肌梗死患者80例入选对照组,对比分析其MTWA最大值、LVEF、心率变异性SDNN值。结果急性心肌梗死组MTWA最大值高于对照组,而LVEF值、心率变异性SDNN值低于对照组。急性心肌梗死两亚组间比较,恶性心律失常亚组MTWA最大值高于无恶性心律失常亚组,而LVEF值、心率变异性SDNN值低于无恶性心律失常亚组。差异有统计学意义(P>0.05)。结论 MTWA最大值、LVEF和心率变异性与AMI患者住院期间恶性心律失常的发生有相关性,可用于AMI患者的危险分层。     

微伏级T波电交替对未植入ICD的心力衰竭患者危险度预测的Meta分析

目的：用Meta分析方法系统性评价微伏级T波电交替（MTWA）对未植入体内自动除颤器（ICD）的心衰患者恶性心律失常和死亡的预测价值。方法检索1990年1月~2013年6月关于运动负荷试验时异常的MTWA对未植入ICD的心衰患者预后预测的前瞻性临床研究。通过χ2统计量结合I2统计量进行异质性检验,用倒方差法固定效应模型分析MTWA对恶性心律失常和死亡的风险,得到合并效应指标风险比（hazard ratio,HR）及其95％可信区间（CI）。结果共有7项研究被纳入,总样本量2953人。其中662人MTWA阳性,1705人MTWA阴性,340人MTWA不确定,246人MTWA非阴性（包括阳性和不确定性）。和MTWA阴性的患者相比较,MTWA异常的患者发生恶性心律失常和死亡的危险度增加（HR为4.51,95%CI：2.28～8.89,P＜0.001）。结论 MTWA检测进行危险分层的评估对未植入ICD的心衰患者恶性心律失常事件和死亡有预测价值。     

Exercise-induced quantitative microvolt T-wave alternans in hypertrophic cardiomyopathy

Background/Purpose

Patients with hypertrophic cardiomyopathy (HCM) have elevated risk for sudden cardiac death (SCD). Our study aimed to quantitatively characterize microvolt T-wave alternans (TWA), a potential arrhythmia risk stratification tool, in this HCM patient population.

Quantitative assessment of microvolt T-wave alternans in patients with congestive heart failure

INTRODUCTION: T-wave alternans has been shown to be linked to the genesis of ventricular tachyarrhythmias. Currently, only qualitative assessment of microvolt T-wave alternans (MTWA) is recommended in clinical practise. Whether quantitative assessment of MTWA yields complementary information is unknown. METHODS AND RESULTS: Noninvasive MTWA determination was performed in 204 consecutive patients with ischemic or nonischemic cardiomyopathy. Of those, 100 tested MTWA positive. In these recordings, MTWA magnitude was quantitatively assessed (alternans voltage, V(alt)). Patients were followed for a mean of 17 months. Ventricular tachyarrhythmic events constituted the study endpoint. Patients with nonischemic cardiomyopathy had a higher V(alt) than patients with ischemic cardiomyopathy (10.3 +/- 9.2 [median 7.2] vs 6.2 +/- 3.2 [median 4.6] microV; P = 0.007). The number of MTWA-positive ECG leads was also higher in patients nonischemic cardiomyopathy (7.3 +/- 2.4 [median 8] vs 6.0 +/- 2.5 [median 6]; P = 0.016). Patients who suffered an arrhythmic event during follow-up had higher MTWA voltages (10.8 +/- 10.0 [median 8.8] vs 7.4 +/- 5.7 [median 6.4] microV; P = 0.05) a higher number of MTWA-positive ECG leads (7.6 +/- 2.4 [median 8] vs 6.4 +/- 2.5 [median 6]; P = 0.05) compared to patients with an uncomplicated course. CONCLUSION: Patients with nonischemic cardiomyopathy and patients with tachyarrhythmic complications have more extensive MTWA possibly reflecting more extensive myocardial damage and a higher arrhythmia propensity.     

右心室室性心动过速患者时域法微伏级T波电交替特征及其临床意义

目的探讨右心室室性心动过速患者时域法微伏级T波电交替（MTWA）特征及其临床意义。方法采用活动平板时域法分别对35例致心律失常性右心室心肌病（ARVC）患者[其中男性28例,平均年龄（38．6±11,0）岁]、10例特发性右心室室性心动过速（IRVT）患者[其中男性7例,平均年龄（41．9±15．4）岁]和60例健康对照者[男性42例,平均年龄（41．0±14．9）岁]进行MTWA检测,记录胸前V1～V6导联的MTWA值,确定胸前各导联的最大值,以Max Valt表示。分析比较不同组别各导联MTWA值及Max Valt值的差异。结果ARVC组各导联MTWA值和Max Valt值均明显高于对照组（P〈0．01）;IRVT组各导联的MTWA值和Max Valt值比对照组升高,但差异无统计学意义（P〉0．05）;ARVC组和IRVT组比较,V4导联MTWA值及MaxVah值明显较高（P〈0．05）;接受者操作特性（receiver operating characteristic,ROC）曲线分析表明,以Max Valt〉11．5μV鉴别诊断ARVC的敏感性为74．3％,特异性为80．0％;ARVC组中,近一年内有持续性室速发生的患者较无室速发作患者V2～V6导联的MTWA值以及Max Valt值的差异有统计学意义。结论渐量修正平均时域法检测显示,ARVC患者MTWA值和Max Valt值均明显升高．MTWA佰可以反映ARVC患者近期室性心动过速的发作。     

Microvolt T-wave alternans for risk stratification of cardiac events in ischemic cardiomyopathy: A meta-analysis

Background

The ability of microvolt T-wave alternans (MTWA) for risk stratification of cardiac events in patients with ischemic cardiomyopathy (ICM) has not been well established.

Methods

The authors systematically reviewed current literature and carried out a meta-analysis to determine the ability of MTWA to predict the outcome severity after ICM. Major endpoints include composite endpoint of cardiac mortality and severe arrhythmic events in primary prevention of patients with ICM, as well as all-cause mortality (cardiac death, and/or non-cardiac death).

Results

Seven trials were included by using MTWA for risk stratification of cardiac events in 3385 patients with ICM. All patients were distributed into two groups according to the results of MTWA tests: non-negative group included positive and indeterminate, and negative group. Compared with the negative group, non-negative group showed increased rates of cardiac mortality or severe arrhythmic events (RR = 1.65, 95%CrI = 1.32, 2.071), sudden cardiac death (SCD) (RR = 2.04 95%CrI = 1.11, 3.75), and all-cause mortality (RR = 2.11, 95%CrI = 1.60, 2.79). The funnel plot revealed that there might be bias within current publications. The fail-safe number of composite endpoint and all-cause mortality was 14.42 and 18.93, respectively (when P = 0.01). The fail-safe number of SCD was 1.07 (when P = 0.05), which may be caused by the small case number of included studies and some patients with ICD included.

Conclusions

The non-negative group of MTWA had a nearly double risk of severe outcomes compared with the negative group. Therefore, MTWA represents a potential useful tool for judging the severity of ICM.     

微伏极T波电交替对心肌梗死急性期患者发生恶性心律失常的预测价值

目的评估微伏极T波电交替（MTWA）能否预测急性心肌梗死早期患者恶性心律失常的发生。方法起病7d内的急性ST段抬高型心肌梗死患者175例入选,根据起病12h内有无行直接经皮冠脉介入治疗（PCI）分为两亚组：Ia组（n=68行直接PCI）,Ib组（n=107未行直接PCI）。另选无心肌梗死来我院健康体检者82例作为对照组。所有入选者均做动态心电图用时域分析法检测MTWA最大值,用超声心动图检测左心室射血分数（LVEF）,用心室晚电位分析仪检测心室晚电位,观察住院期间有无恶性心律失常发生,并比较上述这些指标组间有无差异,用Logistic回归分析筛选恶性心律失常的预测因子。结果心肌梗死组合并糖尿病者高于对照组,Ib组合并糖尿病者高于Ia组。急性心肌梗死组恶性心律失常发生率、心室晚电位阳性率和MTWA最高值均高于对照组,而LVEF值低于对照组。急性心肌梗死两亚组间比较,Ib组恶性心律失常发生率、心室晚电位阳性率和MTWA最大值均高于Ia组,而LVEF值低于Ia组。Logistic回归分析结果显示MTWA最大值、LVEF、心室晚电位阳性率和有无糖尿病是患者是否发生恶性心律失常的独立预测因子,相关系数R分别为0．34、0．29、0．21、0．13,相对危险度（OR）分别为2．82、1．55、1．36、0．87,MTWA的相关性最强（R=0．34）,相对危险度最高（OR=2．82）。当LVEF和心室晚电位进入回归方程时,决定系数R^20．448,增加MTWA最大值进入回归方程后,决定系数R^2显著增加至0．628。结论MTWA最大值、LVEF和心室晚电位是早期急性心肌梗死患者恶性心律失常发生的预测因子,MTWA的预测价值优于LVEF和心室晚电位。如果三者联合运用能更好地预测早期急性心肌梗死患者恶性心律失常发生。     

Effect of bundle branch block on microvolt T-wave alternans and electrophysiologic testing in patients with ischemic cardiomyopathy

BACKGROUND: T-wave alternans (TWA) and electrophysiology study (EPS) are used for risk stratification for sudden death. OBJECTIVE: The purpose of the study was to determine the effect of bundle branch block or intraventricular conduction delay on TWA and EPS. METHODS: 386 patients with coronary artery disease, nonsustained ventricular tachycardia, and left ventricular ejection fraction < or =40% underwent TWA and EPS, and were followed for 40 +/- 19 months. RESULTS: Patients with wide QRS were more likely than narrow QRS patients to have nonnegative TWA (77% vs 63%, P <.01) or positive EPS (60% vs 48%, P = .03). Nonnegative TWA predicted the combined endpoint of ventricular tachyarrhythmia or death in narrow QRS (HR = 1.64, P = .04) but not wide QRS patients (HR = 1.04, P = .91). Similarly, positive EPS predicted the combined endpoint in narrow QRS (HR = 2.28, P <.001) but not wide QRS patients (HR = 0.94, P = .84). In multivariate analysis, QRS width and TWA, as well as QRS width and EPS, were independent predictors of events. There was no TWA- or EPS-based difference in arrhythmia-free survival within any specific wide QRS morphology. CONCLUSION: TWA and EPS are more often abnormal in patients with a wide QRS than in those with a narrow QRS. In patients with narrow QRS, both TWA and EPS stratify patients according to their risk of ventricular tachyarrhythmia or death. However, among patients with a wide QRS, regardless of specific QRS morphology, the risk is high and comparable regardless of TWA or EPS results. Therefore, the only truly low-risk group consists of those patients with negative test results and a narrow QRS.     

Biventricular pacing does not affect microvolt T-wave alternans in heart failure patients

BACKGROUND: Microvolt T-wave alternans (MTWA) is a valuable tool for stratification of patients at risk for sudden death and has recently been approved for this purpose by Medicare. Although right atrial (RA) pacing has been applied for MTWA testing, the effects of other pacing modalities on MTWA have not been systematically studied. Accordingly, it is unknown whether biventricular (BiV) pacing might influence MTWA test results. OBJECTIVE: This study sought to investigate effects of BiV pacing in comparison with other pacing modalities. METHODS: Congestive heart failure patients (n = 30) receiving cardiac resynchronization therapy were included, and a systematic step-up pacing protocol was performed via the implanted cardioverter-defibrillator. RESULTS: Of the overall 120 MTWA tests performed, 67 (56%) were nonnegative. Nonnegative MTWA test results were observed in 18 patients (60%) during RA stimulation, whereas 17 (57%), 15 (50%), and 17 test results (57%) were nonnegative during right ventricular (RV), left ventricular (LV), and BiV pacing, respectively. Seven (23%) patients were MTWA negative for all pacing sites. Results of MTWA assessment during RA pacing were concordant with results obtained with RV pacing in 25 (83%) patients (kappa = 0.66, P = .0003), to LV pacing in 21 (70%) patients (kappa = 0.4, P = .025), and to BiV pacing in 25 (83%) patients (kappa = 0.66, P = .0003). Positive and negative predictive values of nonnegative MTWA test results obtained during RA pacing for a similar result obtained with RV pacing were 88% and 76%. Respective values were similar for other pacing modalities (80% and 60% for LV; 88% and 76% for BiV pacing). CONCLUSION: There is a high level of concordance between MTWA test results obtained during RA pacing and other pacing modalities, and MTWA assessment seems not to be influenced by BiV stimulation in congestive heart failure patients. In general, BiV pacing does not seem to affect an arrhythmogenic substrate as detected by MTWA testing.     

心动过速心肌病的临床特点及与扩张性心肌病的对照分析

目的 探讨心动过速心肌病（TCM）的诊断线索.方法 选取我院2010年1月～2013年1月诊断为TCM的患者6例,随机1∶3匹配年龄（±5岁）和射血分数相近、同性别、同年出院诊断为扩张性心肌病（DCM）的患者18例,分析两类心肌病的临床特点和治疗结果.结果 与TCM组相比,DCM组急性期入院时心率较低,两组分别为（99.4±10.5）次/分和（146±20.4）次/分（P＜0.05）,在心衰缓解时心力率竭显著降低,两组分别为（74.9±8.8）次/分和（122.5±24.9）次/分（P＜0.05）.TCM组术后3个月心脏显著缩小、左室射血分数显著上升（P＜0.05）,而DCM组出院后3个月无明显变化.结论 与DCM相比,TCM的心力率竭在心衰急性期、缓解期显著加快,即使在缓解期也常＞90次/分.故对心肌病患者,须注意鉴别并积极治疗心动过速.