T波电交替计算机检测及其临床研究进展

T波电交替现象可见于长QT综合征、急性心肌缺血、变异型心绞痛、心脏性猝死以及电解质紊乱等。它在预测室性心律失常方面与电生理检查具有高度的一致性,是恶性室性心律失常和心脏性猝死的独立预测指标,是评定恶性心律失常以及心脏性猝死的可信、实用的技术之一。现在,T波电交替已经成为了一种廉价、方便的非侵入式心电检测方法。现综述T波电交替的研究背景、产生机制、检测方法及其临床研究,并简要分析了T波电交替的研究方向和发展前景。     

T波电交替在心脏性猝死预警中的应用——应用T波电交替预警心脏性猝死在中国势在必行

心脏性猝死（Sudden cardiac death，SCD）是一个威胁公共卫生健康的重要社会问题。美国流行病学调查表明，SCD是仅次于各种肿瘤所致死亡的第二大死亡原因。美国平均每年约有45万例心脏性猝死患者。研究证实，约88％的心脏性猝死原因为心律失常，其中恶性室性心律失常最多，约占83％。在发生致命性室性心律失常的人群中，冠心病为主要病因，约占80％。临床研究显示，针对心脏性猝死的高危人群，给予抗心律失常药物治疗不能有效防止SCD。近年来应用ICD一级和二级预防SCD的临床研究证实：ICD可显著减少SCD的死亡率。     

应用T波电交替预警心脏性猝死在中国势在必行

心脏性猝死(Sudden car-diac death,SCD)是一个威胁公共卫生健康的重要社会问题。美国流行病学调查表明,SCD是仅次于各种肿瘤所致死亡的第二大死亡原因。美国平均每年约有45万例心脏性猝死患者。研究证实,约88%     

T波电交替

Ｔ波电交替 (Ｔｗａｖｅａｌｔｅｒｎａｔｉｏｎ ,ＴＷＡ)是指心电图上Ｔ波幅度、形态的逐搏交替变化。反映心肌复极变化的Ｔ波电交替与反映心肌除极变化的ＱＲＳ波电交替两者均呈频率依赖性 ,但其电生理基础及临床意义却迥然不同。ＴＷＡ阳性者与发生恶性室性心律失常的倾向性呈明显正相关 ,而ＱＲＳ波电交替在快频率的阵发性室上性心动过速时较为常见 ,但它与室性心律失常之间并无相关性。肉眼可见的ＴＷＡ在 1910年即被Ｌｅｗｉｓ发现并确定其为室性心动过速 /心室颤动 (室速 /室颤 )及心性猝死的先兆。此后ＴＷＡ一直受到学者们的关注 ,…     

动态心电图检测T波电交替

T波电交替是心室复极不一致的表现，提示心肌电活动不稳定，是患者发生恶性室性心律失常和心脏性猝死的强有力的独立预测指标。在常规心电图上观察到的T波电交替幅度为毫伏级（mV），又称显性T波电交替。而目前T波电交替的检查已发展为肉眼看不见、幅度为微伏级（μV）的电交替，又称微伏级T波电交替（microvolt Twave alternans，MTWA），需借助特殊的诊断系统和专用软件检测。     

心肌炎与T波电交替

患者女,2岁。2月前有上感病史,近期咳嗽、哭闹,查心肌酶:AST 54u/L、CK212 u/L、CK—MB 48u/L、LDH 518 u/L,HBDH 478 u/L。以心肌炎收入院。入院后心脏彩色多普勒超声检查:室间隔略变薄(0.24)cm。运动度略减低,左室下壁局部心肌回声增强、变薄、运动度明     

早期复极综合征患者微伏级T波电交替研究

目的探讨早期复极综合征(ERS)患者微伏级T波电交替发生情况。方法随机入选30例ERS患者和30名体检人群,分为ERS组和对照组。给予动态十二导心电图监测24h,利用时域法分析微伏级T波电交替的发生率,同时记录室性心律失常的发生情况。结果 ERS组微伏级T波电交替的发生率为66.7%,而对照组为13.3%(P0.01)。ERS组和对照组微伏级T波电交替值分别为(49±21)μV和(27±10)μV。ERS组中,微伏级电交替阳性患者的室性早搏发生率高于微伏级电交替阴性患者(45%vs 10%,P0.05)。结论微伏级T波电交替对ERS患者恶性度可能有一定的评估价值。     

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。     

T波电交替与室性心律失常的相关性分析

目的 对T波电交替(TEA)与室性心律失常(VAR)进行相关性分析。方法 对112例住院患进行24h动态心电图(DCG)检查与分析。结果 TEA其24hDCG检出VAR Lown氏3级以上其发生率显高于无TEA。结论 TEA不受束支阻滞和心律不齐影响，对折返和触发激动引起的VAR都能有效预测，不失为临床参考的一项有效指标。     

T-Wave Alternans During Ambulatory Ischemia in Patients with Stable Coronary Disease

Background: T-wave alternans is a marker of vulnerability to ventricular tachyarrhythmias and has been documented during myocardial ischemia associated with angioplasty, bypass graft occlusion, and episodes of Prinzmetal's variant angina. We examined whether this phenomenon was present during ambulatory ischemia in ten patients randomly selected from the placebo phase of the Angina and Silent Ischemia Study [ASIS]. Methods: The eligibility criteria for participation in the ASIS study were stable coronary disease, a positive exercise stress test, and verified ischemic episodes during ambulatory ECG (AECG) monitoring. For each patient, one ischemic episode was analyzed which met the criteria of > 2-mm ST segment depression for > 3 minutes with a relatively stable ST segment baseline of > 1 hour preceding the index episode. T-wave alternans was measured using the spectral analytical technique of complex demodulation. Results: In the stable coronary patients of the ASIS trial, we found that T-wave alternans magnitude nearly tripled from 0.27 ± 0.02 mV × ms before ischemia onset to 0.77 ± 0.08 mV × ms (P < 0.01) during ischemic episodes. Heart rates ranged from 83 ± 2.9 beats/min prior to ischemia to 116 ± 2.5 beats/min during ischemia (P < 0.01). There was no statistical correlation between the magnitude of the ST segment depression > 2 mm and the ischemia-induced increase in T-wave alternans. Conclusions: We conclude that T-wave alternans often occurs in association with ambulatory ischemia. Thus, risk assessment in stable coronary patients may be enhanced by monitoring both ST segment deviation and T-wave alternans as they measure relevant but fundamentally different electrophysiological properties.     

Enhancing Specificity Without Sacrificing Sensitivity: Potential Benefits of Using Microvolt T-Wave Alternans Testing to Risk Stratify the MADIT-II Population

The MADIT-II study (Moss et al., N Engl J Med 2002;346:877-883) demonstrated that implantation of a cardioverter/defibrillator (ICD) reduced mortality from 19.8% to 14.2% during 20 months of follow-up in patients with prior myocardial infarction and left ventricular ejection fraction 相似文献   

Ventricular tachyarrhythmias,myocardial ischemia,and sudden cardiac death in patients with hypertensive heart disease

Hypertensive heart disease is increasingly considered to be a strong and independent risk factor for sudden cardiac death. Ventricular tachyarrhythmias in these patients are common and mainly the result of electrophysiologic abnormalities and increased electrical vulnerability of the hypertrophic myocardium. However, proarrhythmia in the hypertrophic heart often is facilitated and aggravated by electrolyte disturbances, the sympathoadrenergic tone, transient blood pressure crisis, and especially by the occurrence of myocardial ischemia. Myocardial ischemia in the setting of hypertensive heart disease may result from stenotic lesions in large and/or small coronary artery vessels and, in the absence of both, will result from the altered cellular oxygen supply and consumption in the hypertrophic myocardium. Recent studies have shown that acute and transient myocardial ischemia are common in many hypertensives, often fail to be symptomatic, and that the dynamic interaction of left ventricular hypertrophy, transient myocardial ischemia, and ventricular tachyarrhythmias may provide a crucial link for the high incidence of sudden cardiac death in patients with hypertensive heart disease.     

Can the mode of death be predicted in patients with angiographically documented coronary artery disease?

To determine whether sudden versus non-sudden cardiac death could be predicted in high risk patients, 1157 medical patients were followed for an average of 46 months after a diagnostic coronary angiogram and 18 clinical, hemodynamic, and angiographic variables known to be associated with a high risk of mortality were analyzed. The total group of 141 deaths was classified into 3 subgroups: (1) 82 sudden deaths (less than 1 hour after onset of symptoms); (2) 46 deaths due to acute myocardial infarction with or without heart failure, and (3) 13 deaths unrelated to cardiac symptoms. In a subset of 64 patients, the duration of electrical systole (QTc) was calculated before angiography and before death. A comparison was made of QTc measurements at entry with QTc values of subjects with normal coronary arteries and normal left ventricular function. Deaths from cardiac causes could often be predicted from older age, male sex, history of myocardial infarction, unstable angina, congestive heart failure, abnormal cardiothoracic ratio, multivessel disease, abnormal left ventricular contraction, and abnormal ejection fraction. However, these variables did not discriminate between sudden and nonsudden cardiac deaths and both modes of death were characterized by depressed left ventricular function and multivessel coronary disease. During follow-up the incidence of acute myocardial infarction was not different in patients with cardiac and noncardiac deaths and in long-term survivors. However, patients dying from cardiac causes had a higher incidence of heart failure. Patients dying suddenly did not present new infarctions during follow-up whereas patients dying from acute myocardial infarction had a 13% incidence of prior infarction and a higher incidence of heart failure. In addition, QTc at entry was longer in nonsurvivors than in normal subjects (p less than 0.0001) and patients experiencing sudden death exhibited the highest incidence of QTc prolongation (greater than or equal to 440 ms) during follow-up (p less than 0.05). We conclude that: (1) although the severity of coronary disease and left ventricular dysfunction are closely related to cardiac mortality, they do not discriminate between sudden and nonsudden cardiac deaths; (2) patients experiencing sudden death are characterized by a low incidence of new myocardial infarction or congestive heart failure and prolongation of the QTc interval during follow-up.     

Frequency Response Characteristics Required for Detection of T-Wave Alternans During Ambulatory ECG Monitoring

Background: T-wave alternans has been increasingly implicated as a potential marker of vulnerability to ventricular tachyarrhythmias in both experimental and clinical investigations. However, the suitability of ambulatory ECG (AECG) recorders for monitoring this parameter has not been systematically studied. Methods: We evaluated the frequency response characteristics and performance in monitoring a computer simulated alternans signal in three brands of amplitude-modulated (AM) and one frequency-modulated (FM) recorder and compared the results to those of the reference digital AECG unit. Results: A common feature of the AM recorders was distortion due to electronic head resonance, particularly at heart rates in the range of 60–100 beats/min. The maximum distortion of T-wave morphology by the AM units was —6% to +28%. Conclusions: We conclude that digital and FM recorders are preferable for AECG monitoring of T-wave alternans. AM recorders can be used if the distortion is not excessive.     

T波电交替的研究进展

T波电交替是指在规整的心律时,体表心电图上T波形态、极性和振幅出现逐搏交替变化的现象,其与恶性室性心律失常以及心脏性猝死的发生有着极为密切的联系。T波电交替的检测方法有频域分析和时域分析方法两种。临床试验证实,T波电交替对恶性室性心律失常事件的预测价值与有创的电生理检测价值相似。但微伏级T波电交替检测作为一种无创的检测手段,其对于发生各种致死性心脏病危险分级的作用仍需要临床实验进一步研究证实,现就T波电交替的发生机制、临床意义以及发展现状等进行综述。     

老年冠心病和高血压患者再发心脏事件的临床危险因素

目的老年冠心病和高血压患者再发急性心肌梗死（ＡＭＩ）和心原性猝死（ＳＣＤ）等心脏事件的危险较大，我们研究这些患者的有关临床特征对再发心脏事件的影响。方法随访３９０例老年冠心病和高血压患者２～８．５年，记录年龄、性别、糖尿病、吸烟、心电图ＳＴ－Ｔ异常、总胆固醇与高密度脂蛋白胆固醇比值≥４．５、冠心病并高血压、左室肥厚、无痛性心肌缺血和复杂室性心律失常等临床特征及ＡＭＩ或ＳＣＤ发生情况。结果　共有４８例患者发生ＡＭＩ或ＳＣＤ。Ｋａｐｌａｎ－Ｍｅｉｅｒ法分析得出８年累积再发心脏事件率２１．８％。单因素分析表明，除年龄外的９个临床危险因素都使再发心脏事件率显著增加。Ｃｏｘ多因素分析表明，上述后５个危险因素是再发心脏事件的重要独立预报因素。结论为改善老年冠心病和高血压患者的预后，对上述临床危险因素应予以足够重视，并加以控制。