心肌缺血致室性心动过速的发生机制探讨

对冠心病患者心肌缺血（ＭＩ）时伴室性心动过速的１９例病人（Ｉ组）与无室速的４６例病人（Ⅱ组）进行对比分析。结果显示：２组每天ＭＩ总阵次和总时间有非常显著性差异（Ｐ均〈０．０１），Ｉ组全程持续性ＭＩ高于Ⅱ组（Ｐ〈０．０５）；Ｉ组中伴室速发作的ＭＩ持续时间、最大ＳＴ段压低幅度高于无室速的ＭＩ（Ｐ均〈０．０１）；Ｉ组心室晚电位阳性及３级以上室早总发生率均明显高于Ⅱ组（Ｐ均〈０．０１）。提示冠心病患者ＭＩ     

急性心肌梗塞的溶栓疗法对心室晚电位的影响

本文观察了６０例急性心梗病人，溶栓对心室晚电位（ＶＬＰ），持续性室速（ＶＴ）及死亡率的影响。临床发现，溶栓组ＶＬＰ的检率３例（１０％），持续性室速的发生率６例（２０％），死亡率３例（１０％），非溶栓组分别为１０例（３３％），ＶＴｌ５例（５０％），死亡率１０例（３３％），二组相比有显著差异（ｐ＜０．０５）。再通组ＶＬＰ的检出率１例（４．３％），ＶＴ的发生率２例（４．３％），非再通组分别为２例（２８％）和４例（５７％），二组相比有显著差异（Ｐ＜０．０５和Ｐ＜０．０１）。再通组与非再通组的死亡率无显著差异（Ｐ＞０．０５）。因此，本文提示溶栓能降低心梗病人ＶＬＰ及ＶＴ的发生率，降低心梗病人的死亡率。     

急性心肌梗塞伴心律失常患者心室晚电位与肌酸激酶的关系

作者报道急性心肌梗塞（ＡＭＩ）患者早期（一周内）伴有室性心律失常（ＶＡ）４４例，其心室晚电位（ＶＬＰ）阳性率２９．５％与血清肌酸激酶（ＣＫ）及同功酶（ＣＫ－ＭＢ）峰值呈正相关；与年龄，性别，心梗部位无关。室速（ＶＴ）和室颤（ＶＦ）组的ＶＬＰ阳性率明显高于室早组（Ｐ＜０．０５）。但两组的ＣＫ，ＣＫ－ＭＢ比值无统计学意义。     

急性心肌缺血QT离散度变化与室速室颤的关系

目的：探讨冠心病患者急性心肌缺血对 Ｑ Ｔ 离散度（ Ｑ Ｔｄ）、校正后的 Ｑ Ｔ 离散度（ Ｑ Ｔｃｄ）的影响及其与室性心动过速（简称室速）、心室颤动（简称室颤）的关系。方法：选择７１例确诊为冠心病心绞痛的患者,分成室速室颤组（１３例）和非室速室颤组（５８例）,测定每例患者心绞痛发作前、发作时及发作后的 Ｑ Ｔｄ、 Ｑ Ｔｃｄ。结果：心绞痛发作时 Ｑ Ｔｄ、 Ｑ Ｔｃｄ 均显著大于心绞痛发作前和发作后（均 Ｐ ＜ ０．０１）,后两者比较无显著性差异（ Ｐ ＞ ０．０５）。室速室颤组心绞痛发作时 Ｑ Ｔｄ、 Ｑ Ｔｃｄ均显著大于非室速室颤组（均 Ｐ ＜ ０．０１）。心绞痛发作前以 Ｑ Ｔｄ≥８０ ｍ ｓ 为标准,则预测室速室颤发生的敏感性为５３．８％ ,特异性为８２．８％ ,准确性为７７．５％ ;心绞痛发作时以 Ｑ Ｔｄ≥１００ ｍ ｓ 为标准,则预测室速室颤发生的敏感性为９２．３％ ,特异性为８４．５％ ,准确性为８５．９％ 。结论：冠心病患者急性心肌缺血时 Ｑ Ｔｄ、 Ｑ Ｔｃｄ 显著增大,易发生室速室颤。急性心肌缺血时的 Ｑ Ｔｄ、 Ｑ Ｔｃｄ 变化可能是预测室速室颤发生更为敏感的指标。     

窗起点对信号平均心电图频谱时间标测的影响

本研究比较了两种窗起点对频谱时间标测分析结果的影响。窗起点位于滤波综合ＱＲＳ波终未电压低于４０μＶ处时，其敏感性、特异性、阳性预告值及阴性预告值均高于窗起点位于ＱＲＳ波终点前２０ｍｓ时。窗起点位于ＱＲＳ波终点前２０ｍｓ时，持续性室速／室颤组与健康人组晚电位阳性率无显著差异。证明前者优于后者。     

冠心病患者的心室晚电位、室性早搏与心肌复极离散度的关系

对７０例冠心病患者和２１例健康人的心电图数值进行测量，并对心室晚电位、室性早搏与心电图各测值的关系进行研究。结果：①心绞痛和陈旧性心肌梗塞患者ＱＴｃ、ＱＴｄ、ＪＴ、ＪＴｃ、ＪＴｄ及ＪＴｃｄ明显高于健康对照组（Ｐ＜０．０５或＜０．０１）。陈旧性心肌梗塞组患者ＱＴｃ、ＱＴｄ、ＱＴｃｄ及ＪＴｄ、ＪＴｃｄ高于心绞痛组（Ｐ＜０．０５或＜０．０１）。②心室晚电位阳性的冠心病患者的ＱＴｄ、ＱＴｃｄ、ＪＴｄ、ＪＴｃｄ明显高于心室晚电位阴性的冠心病组（Ｐ＜０．０５或＜０．０１）。③冠心病伴室性早搏者ＱＴｃ、ＱＴｄ、ＱＴｃｄ、ＪＴ、ＪＴｃ、ＪＴｄ、ＪＴｃｄ明显增加（Ｐ＜０．０５或＜０．０１）。提示冠心病存在明显心肌复极不均匀，心室晚电位和室性早搏与心肌复极离散度有关。     

倍他乐克对心室晚电位阴转作用的临床研究

本文探讨β阴滞剂倍他乐克对心肌梗塞后心室晚电位的阴转作用。心肌梗塞后第22±9天检测心室晚电位阳性103例，随机分为组Ⅰ（56例），予倍他乐克口服，组Ⅱ（47例）予安慰剂口服。服药后四周、一年查心室晚电位，Holier、心脏超声。结果组Ⅰ四周、一年的晚电位阴转率分别为51．8％（29／56），和60.7％（34／56），组Ⅱ分别为12．8％（6／47）和19．1％（9／47）；组Ⅰ的阴转率均明显优于组Ⅱ（P＜0.01）。一年后持续性室速、室颤发生率组Ⅰ14．3％（8／56）；组Ⅱ34.04％（16／47）；猝死的发生率组Ⅰ3.6％（2／6），组Ⅱ14．9％（7／47）、组Ⅰ与组Ⅱ对比有显著差异（P＜0．05）。结果显示，倍他乐克对MI后心室晚电位有阴转作用，对持续性室速、室颤和猝死也有一定的预防作用。     

心室晚电位心率变异对急性心肌梗死者心律失常事件发生 ...

目的 通过４０例急性心肌梗死（ＡＭＩ，Ａ组）者的心室晚电位（ＶＬＰ）、心率变异（ＨＲＶ）检测，与４０例正常人（Ｂ组）进行对比。结果 Ａ组ＨＲＶ（ＳＤＮＮ）较Ｂ组明显缩小（Ｐ〈０．００１），ＶＬＰ阳性率明显增加（Ｐ〈０．０１）。室性心律失常（ＶＴ）事件组（Ａ１组）与非事件组（Ａ２组（的２项指标比较有非常显著差异（Ｐ〈０．００５）并且ＨＲＶ特异性同。结论 ２者同时监测可增加预测指标的特异性、有效性及相     

急性心肌梗死心率变异性与临床背景的关系

分析８４例急性心肌梗死（ＡＭＩ）后两周患者的心率变异性（ＨＲＶ），旨在了解ＡＭＩ后ＨＲＶ与临床资料的关系。结果：１．ＨＲＶ各项指标与年龄呈负相关，女性患者的ＨＲＶ较男性低（Ｐ＜０．０５）。２．ＨＲＶ与左室射血分数、心肌梗死部位及是否合并高血压无明显关系，但糖尿病患者时域指标中的Ｓｔ．ｇｅｏｒｇｅｓ指数较无糖尿病患者显著下降（Ｐ＜０．０１）。３．心室晚电位阳性者的ＨＲＶ时域指标ＳＤ、Ｓｔ．ｇｅｏｒｇｅｓ指数较阴性者显著下降（Ｐ＜０．０５）。结论：年龄、性别、晚电位及糖尿病对ＨＲＶ有影响     

急性心肌梗塞患者心率变异性与心室晚电位和左室射血分数以及室性心律失常关系的探讨

采用动态心电图统计２４小时全部窦性ＲＲ间期，以测定３０例急性心肌梗塞（ＡＭＩ）后１７±４ｄ的心率变异性（ＨＲＶ）ＲＲ间期均值的标准差（ＳＤ）指标，并同时测定心室晚电位（ＶＬＰ）、左室射血分数（ＬＶＥＦ）和用Ｈｏｌｔｅｒ记录室性心律失常，分析它们之间的关系。ＶＬＰ阳性与阴性组的ＨＲＶ无显著性差异（Ｐ＞０．０５）；ＨＲＶ与ＬＶＥＦ呈显著正相关（Ｐ＜０．００５）；Ｈｏｌｔｅｒ记录到短阵室性心动过速、成对室性早搏（简称室早）和每小时室早数＞１００次的ＳＤ值显著低于未记录到室早和每小时室早数＜１０次者（Ｐ＜０．００１）。提示ＡＭＩ后ＨＲＶ降低与ＶＬＰ阳性与否无关；低ＬＶＥＦ者ＨＲＶ亦降低；ＨＲＶ降低者其室性心律失常发生率显著增加。联合应用上述方法和指标，可望提高对ＡＭＩ后高危患者预测的准确率。     

Detection of prior myocardial infarction patients prone to malignant ventricular arrhythmias using wavelet transform analysis

Ventricular tachycardia (VT) and ventricular fibrillation (VF) leading to sudden cardiac death remains responsible for significant mortality in patients with prior myocardial infarction (MI). The study population consisted of 50 normal controls and 50 patients with prior MI. The MI subjects were divided into 3 groups: VT/VF (-) group; 25 patients without ventricular tachyarrhythmia, VT group; 13 patients with sustained VT, and VF group; 12 patients with resuscitated VF. The parameters on the signal-averaged ECG and the frequency components recorded from the wavelet-transformed ECG were compared. The high-frequency components (HFC; 80-150 Hz) were developed in the MI group to a greater extent than those in the control group. Among the MI patients, the HFC were more developed in the VT and VF groups than in the VT/VF (-) group. In the VF group, the positive rate of LP was 50%. Meanwhile, when the peak power value at 150 Hz > 300 was defined as abnormal, the HFC was detected in 13 (100%) patients in the VT group and 12 (91.7%) in the VF group. The sensitivity of the abnormal HFC in identifying patients with VT/VF was higher than that of SAECG (96% versus 72%), although the specificity remained similar (68.5% versus 64.3%). Abnormal HFC recorded from the wavelet-transformed ECG may be a novel factor in detecting patients who are prone to VT/VF.     

Wavelet Analysis of Signal‐Averaged Electrocardiograms

Background: Wavelet representation is able to detect low amplitude patterns even if hidden within signals of much higher amplitudes. Method: A software system has been developed that implements wavelet representation of signal‐averaged electrocardiograms (SAECG). In this system, wavelet analysis leads to 4 numerical parameters that characterize the content of low amplitude perturbations found within the high gain QRS complex. In three substudies, these numerical parameters were compared with the standard time‐domain indices of SAECG. Populations: Normal limits were identified from recordings of 104 normal healthy volunteers (54 males, mean age 50 ± 17 years). Short‐term reproducibility of the numerical indices and of abnormal findings was evaluated in a population of 85 subjects (16 healthy volunteers, 22 patients with documented ventricular tachycardia [VT] without structural heart disease, 30 patients with documented sustained postinfarction VT, and 17 survivors of acute myocardial infarction) who were each recorded three times with 5‐minute periods separating individual recordings. The power of wavelet and time‐domain analyses in distinguishing patients with and without sustained VT after myocardial infarction was assessed using recordings of 53 patients with postinfarction VT and of 53 age, sex, and infarct site matched patients without a history of arrhythmic complications after infarction. Results: The studies have shown that (a) the indices of wavelet analysis are more reproducible than the time‐domain indices, (b) the distinction between patients with and without VT after myocardial infarction is similarly powerful by wavelet and time‐domain analyses, and the association of the positive SAECG analysis with postinfarction VT is highly significant with both analyses (P = 3.94 × 10–14 for wavelet analysis and 2.55 × 10^?9 for time‐domain analysis), the indices of wavelet analysis differ significantly between normals and patients with an uncomplicated history of myocardial infarction (P = 0.02–0.005), while time‐domain indices do not (all parameters NS), (d) in contrast to the time‐domain analysis, wavelet analysis was similarly powerful in identifying VT patients with anterior and inferior infarction (P = 1.4 × 10^?9, n = 30, and P = 2.0 × 10^?15, n = 23, respectively). Conclusion: Wavelet analysis is a highly reproducible method for SAECG processing which (a) is as powerful as the time‐domain analysis for the identification of ischemic VT patients, (b) compared to the time‐domain analysis, is not dependent on infarct site, and is able to distinguish postmyocardial infarction patients without VT from healthy subjects. A.N.E. 2000,5(1):4–19     

Correlation between the signal-averaged electrocardiogram and electrophysiologic study findings in patients with coronary artery disease and sustained ventricular tachycardia

Ventricular late potentials at the end of the surface QRS, detected on the signal-averaged electrocardiogram (SAECG) have been shown to be markers for spontaneous and/or inducible ventricular tachycardia (VT) in patients with coronary artery disease (CAD). We examined the correlations between electrophysiologic study (EPS) findings and SAECG indexes in 50 patients with chronic CAD with documented spontaneous VT/ventricular fibrillation (VF), who had either syncope (24 patients) or aborted sudden cardiac death (SCD). The prevalence of late potentials was significantly higher in the syncope patients (75%) compared with the SCD group (46%) (p less than 0.05). No correlation was found between the ventricular refractoriness and the SAECG indexes. There was a significant difference in quantitative SAECG indexes comparing the induction mode of the sustained VT/VF by single and double versus triple extrastimuli; the types of the induced VT (sustained monomorphic, sustained pleomorphic or VF, noninducible); and the cycle length of the induced sustained monomorphic VT with the high frequency QRS duration (QRSD). In conclusion, differences in prevalence and characteristics of ventricular late potentials were found between patients with syncope and with SCD. The degree of abnormality of SAECG indexes correlated with the type and the mode of induction of sustained VT. The magnitude of QRSD of the SAECG correlated with the cycle length of monomorphic VT. The above findings suggest that in patients with CAD and sustained VT/VF the SAECG variables are related to the area of reentry.     

信号平均心电图频谱时间标测预测急性心肌梗塞后心律失常事件的评价

本文前瞻性地分析了信号平均心电图(SAECG)频谱时间标测(Spectrotemporal Mapping,STM)改良方法的结果对79例急性心肌梗塞(AMI)患者梗塞后发生心律失常事件(AE)的预测价值。79例患者均行SAECG STM分析,生存者均随访1年或以上,平均随访25.3±8.7月,随访率94%。住院与随访期间共12例(15%)发生AE,其中8例为持续性室速/室颤(VTs/VF)(4例复苏失败),4例为猝死。79例中24例(30%)STM结果异常即心室晚电位(LP)阳性。LP阳性组患者发生AE危险性明显高于LP阴性组(33%对7%,P<0.01)。多因素Cox分析STM、LVEF、Holter及UCG室壁活动指数4项变量,显示STM为唯一能预测AMI后AE的指标。STM结果预测AMI后AE的敏感性、特异性、准确性及阳性与阴性预测值分别为67%、76%、75%、33%及93%;预测AMI后VTs/VF的上述指标分别为88%、76%、77%、29%及98%。     

Influence of the infarct site on the identification of patients with ventricular tachycardia after myocardial infarction based on the time-domain and spectral turbulence analysis of the signal-averaged electrocardiogram

In a significant proportion of patients with sustained ventricular tachycardia (VT) following anterior myocardial infarction, the areas of slow conduction are activated early during cardiac depolarization. Therefore, they may not be detected by the standard time-domain analysis of the signal-averaged electrocardiogram (SAECG) which is limited to the terminal part of the QRS complex. Spectral turbulence analysis of the SAECG is a new frequency domain technique which examines the whole QRS complex and may improve identification of patients with sustained VT following anterior infarction. We compared the results of time-domain and spectral turbulence analyses of the SAECG in 53 postinfarction patients with sustained VT and in 53 age-, gender- and infarct site-matched patients without VT. The receiver operator characteristic curves have shown that the time-domain analysis resulted in better identification of patients with VT following inferior than following anterior infarction (e.g., at the sensitivity level of 90%, the corresponding values of specificity were 96 and 90%, respectively), whereas the spectral turbulence analysis performed better in the anterior site of infarction. When both time-domain and spectral turbulence analyses were combined, the accuracy of the SAECG for identification of patients with VT following anterior infarction improved, reaching a specificity of 97% at the sensitivity level of 90%. In conclusion (1) spectral turbulence analysis of the SAECG results in better identification of patients with VT following anterior than following inferior infarction, and (2) the combination of time-domain and spectral turbulence analyses of the SAECG may improve identification of patients with VT following anterior infarction.     

米诺环素预处理对大鼠缺血性室性心律失常的影响

目的观察米诺环素(MC)预处理对大鼠心肌缺血性室性心律失常的影响并探讨其可能机制。方法采用冠状动脉左前降支结扎法建立大鼠心肌梗死(MI)模型。将60只雄性SD大鼠随机分成6组:MI组,MI+MC组,MI+LY294002(LY)组,MI+5-羟基癸酸(5-HD)组,MI+MC+LY组及MI+MC+5-HD组。各组在制作MI模型前分别给予生理盐水、MC、LY、5-HD、MC+LY、MC+5-HD预处理。持续心电监护,观察缺血30 min内各组室性心动过速(VT)和心室颤动(VF)发生率、以及VT+VF持续时间、发生次数和室性心律失常的严重程度。缺血30min后迅速摘取心脏,用TTC法测心肌梗死面积。结果与MI组比较,MI+MC组的VT发生率无明显变化(P0.05),但VF发生率显著降低,VT+VF持续时间、发生次数和严重程度以及心肌梗死面积显著减少(P均0.05);而MI+MC+LY组及MI+MC+5-HD组上述指标与MI组无差异。结论 MC预处理可以减轻大鼠MI诱导的室性心律失常,这种作用可能与3-磷酸肌醇激酶/Akt信号通路和线粒体ATP敏感性钾离子通道的激活有关。     

Late fields of the magnetocardiographic QRS complex as indicators of propensity to sustained ventricular tachycardia after myocardial infarction

INTRODUCTION: Magnetocardiographic (MCG) mapping is a new method to record cardiac signals. This study examined the association of MCG late fields with the propensity to sustained ventricular tachycardia (VT) after myocardial infarction (MI). METHODS AND RESULTS: One hundred patients with remote MI were studied, 38 with and 62 without history of VT. High-resolution MCG and signal-averaged ECG (SAECG) as a comparative method were recorded. Time-domain parameters describing the abnormal low-amplitude end QRS activity, MCG late fields, and SAECG late potentials were analyzed. Late field parameters differed significantly between the patient groups: filtered QRS duration was 137 +/- 26 msec in the VT group and 110 +/- 18 msec in the control group (P < 0.001), and root mean square amplitude of the last 40 msec was 260 +/- 170 and 510 +/- 360 fT (P < 0.001), respectively. The optimal MCG parameter combination yielded a sensitivity of 92% and a specificity of 61% in classification to the VT group, whereas those for SAECG were 63% and 66%. In a subgroup of 63 patients with marked left ventricular dysfunction and comparable stage of coronary heart disease, only MCG (sensitivity 73%, specificity 67%) but not SAECG could assign a patient to the VT group. CONCLUSION: Late fields of the MCG QRS complex indicate propensity to life-threatening arrhythmias in post-MI patients. This discriminative ability persists in the presence of severe left ventricular dysfunction where ECG late potentials lose their informative value. MCG late field analysis is a potential new method for noninvasive risk assessment in post-MI patients.     

Signal-averaged electrocardiographic late potentials in resuscitated survivors of out-of-hospital ventricular fibrillation

The results of signal-averaged electrocardiography and programmed electrical stimulation were evaluated in 25 patients with recurrent sustained ventricular tachycardia (VT) and 46 patients with a history of out-of-hospital ventricular fibrillation (VF) to characterize the electrophysiologic substrate responsible for these different clinical arrhythmia presentations. Patients with VT had a higher incidence of late potentials (VT 83%, VF 50%, p = 0.005). Significant differences between these groups were also noted in response to programmed electrical stimulation. A sustained ventricular arrhythmia was induced in 24 of 25 (96%) patients with a history of VT but in only 27 of 46 (59%) of VF patients (p = 0.005). In addition, VF was induced in 11 (24%) patients in the VF group but in none of the patients in the VT group (p = 0.005). When the 2 groups were compared on the basis of select clinical characteristics, no significant difference in age, sex, presence of coronary artery disease or ejection fraction was noted. The frequency of prior myocardial infarction was significantly higher in the VT group (VT 20 of 25, 80%; VF 24 of 46, 52%; p = 0.03). Finally, no significant relation between the presence of late potentials and induced arrhythmias was noted in either group. The inability of signal-averaged electrocardiography to predict inducibility in VF patients may represent a significant limitation of this technique in identifying patients at risk for sudden cardiac death.     

Prognostic significance of ventricular late potentials in coronary artery disease

By means of high-gain ECG and signal-averaging techniques, we tried to determine the prevalence and prognostic significance of ventricular late potentials (VLPs) in coronary artery disease (CAD). No VLPs were detected in normal subjects (n = 25) or in patients with various noncoronary cardiopathies with sustained ventricular tachycardia and/or fibrillation (VT/VF) (n = 10). Among 92 CAD patients, VLPs were apparent in 35% (32 of 92) at the beginning of the study. The prevalence of VLPs increased to 48% (19 of 40) in the presence of ventricular aneurysm (VA) and to 82% (14 of 17) in the presence of a history of previous sustained VT/VF. To determine the prognostic significance of VLPs, a prospective analysis was conducted during a mean of 7.4 months (range 1 to 22 months). During the follow-up period, 11 patients (12%) presented with an episode of sustained VT/VF, and six of them died from documented VT/VF. Three other patients died from cardiogenic shock. An episode of sustained VT/VF occurred in 31% (10 of 32) of the patients with VLPs vs 2% (1 of 58) of the patients without VLPs (p less than 0.001), and six patients with VLPs died from sustained VT/VF vs none in the group of patients without VLPs (p less than 0.01). This VLP-related increase in arrhythmic risk was still present in the particular subgroup of patients with a history of previous sustained VT/VF (n = 17) and in patients with VA (n = 40). The risk of developing sustained VT/VF was also influenced by the length of the VLP and by a low mean ejection fraction.(ABSTRACT TRUNCATED AT 250 WORDS)     

Relationship between signal-averaged electrocardiography and dangerous ventricular arrhythmias in patients with left ventricular aneurysm after myocardial infarction.

We performed signal-averaged electrocardiography (SAECG) and Holter monitoring, and subsequently followed-up 53 ambulatory patients with left ventricular aneurysm (LVA) after myocardial infarction (MI). A history of spontaneous episodes of sustained ventricular tachycardia (VT) was also analysed. Out of 53 patients, 25 (47%) had an abnormal SAECG. Abnormal SAECG correctly identified nine out of 10 cases with a history of sustained VT. Complex ventricular arrhythmias were detected on Holter monitoring in 23 patients: in five out of 28 with normal SAECG (18%) and in 18 out of 25 with abnormal SAECG (72%) (P less than 0.001). During follow-up (mean 19 months) sustained VT and/or sudden cardiac death (SCD) occurred in eight cases, out of which seven had an abnormal SAECG. The negative predictive value of SAECG (no VT or SCD during follow-up) was very high, 96%, similar to the negative predictive value of a history of sustained VT (93%). Using multivariate analysis only a history of sustained VT was an independent factor in predicting the outcome of patients in this study. We conclude that an abnormal SAECG identifies those post infarction patients with LVA who are prone to complex ventricular arrhythmias. A normal SAECG and an absence of a history of sustained VT strongly indicate that the risk of developing arrhythmic events is very low.