飞行员QT离散度研究

目的 旨在研究飞行员心肌复极不均一性。方法 本文作者利用ＨＰＭ１７７２Ａ－１００型心电图机记录常规１２导联心电图,分别测算了５３例飞行员和３２例地勤人员的ＱＴ离散度（ＱＴｄ）、ＪＴ离散度（ＪＴｄ）、心率校正ＱＴ离散度（ＱＴｃｄ）和心率校正ＪＴ离散度（ＪＴｃｄ）等参数。结果 统计分析显示,无论是从常规１２导联心电图抑或是胸前６导联心电图测算的ＱＴｄ等参数,地勤人员与飞行员之间均无明显差别。例如,飞行     

小儿先天性心脏病QT间期离散度与P波离散度的研究

目的　探讨小儿先天性心脏病QT间期离散度 (QTd)与P波离散度 (Pd)变化。方法　 32 3例 0 0 8～ 16 0 0 (平均3 0 2± 3 0 3)岁先心病患儿 (研究组 )及 77例匹配健康儿童 (对照组 )描记 12导联同步体表心电图。选择波形清晰的 3个心动周期人工测量心率 (HR)、Pd 与QTd。微机数理统计。结果　研究组与对照组比较 ,体重分别为 (12 11± 7 2 0 )kg及 (14 6 3±6 39)kg ,身高分别为 (87 16± 2 2 89)cm及 (94 4 2± 2 1 2 9)cm ;研究组体重减轻 17 2 2 % (P <0 0 1) ,身高降低 7 6 9% (P <0 0 5 )。与对照组比较 ,研究组HR增快 (P >0 0 5 ) ,QTmax及Pmax延长 (P <0 0 1) ,QTd 与Pd 分别增大 5 6 0 3%及 38 33% (P <0 0 1)。结论　先天性心脏病患儿术前心电图QTd 及Pd 明显延长 ,可能与发生室性或房性心律失常有关。     

儿童血管迷走性晕厥QT间期离散度及P波离散度研究

目的　探讨儿童血管迷走性晕厥 (VVS)QT间期离散度 (QTd)及P波离散度 (Pd)的变化。方法　不明原因晕厥(UPS)患儿 5 5例 (研究组 ) ,均进行基础直立倾斜试验 (BHUTT)或 (和 )舌下含服硝酸甘油倾斜试验 (SNTTT)。匹配健康儿童 5 5例为对照 (对照组 )。于BHUTT前一天描记 12导联同步体表心电图 (12ECG)。选择波形清晰的 12ECG 3个心动周期 ,测量心率 (HR)、QTd 与Pd。结果　与对照组比较 ,研究组HR减慢 (P <0 0 1) ,QTmax、QTmin、QTd 延长 (P <0 0 1) ,QTcmax、QTcd增大 (P <0 0 1或P <0 0 5 ) ;Pcmax、Pcmin缩短 (P <0 0 1) ,Pd 及Pcd稍延长 (P >0 0 5 )。QTd、QTcd及Pd、Pcd在VVS患儿男女性别之间无差异(P >0 0 5 ) ,HUTT阳性组与阴性组之间亦未见差异 (P >0 0 5 )。结论　QTd 及Pd 在VVS患儿男女性别及HUTT阳性组与阴性组间未见差异。VVS患儿QTd 及QTcd增大 ,Pd 及Pcd延长不明显 ,临床上要警惕VVS患儿发生室性心律失常。     

QT间期离散度及P波离散度与小儿扩张型心肌病预后的关系

目的　探讨QT间期离散度 (QTd)及P波离散度 (Pd)与小儿扩张型心肌病 (DCM)预后关系。方法　 5 2例DCM患儿 (研究组 ) ,男 31例 ,女 2 1例 ,年龄 3个月～ 18岁 ,平均 (5 79± 5 17)岁 ,死亡 5例。随机匹配健康儿童 5 2例为对照 (对照组 )。受检对象描记 12导联同步体表心电图 ,选择波形清晰的 3个心动周期自动分析合并人工干预测量心率 (HR)、QTd与Pd。结果　研究组较对照组心率增快 (P <0 0 5 ) ,P -R间期 (P <0 0 5 )、QRS间期 (P <0 0 1)及QTc间期 (P <0 0 1)延长 ;QT max增加 (P >0 0 5 ) ,QTd、Pmax、Pmin及Pd延长 (P <0 0 1)。死亡组与存活组比较QTd与Pd无差异 (P >0 0 5 )。结论　QTd和Pd在DCM患儿明显增大 ,但其对估测DCM预后价值有限。     

Q—T间期离散度的临床意义

早已发现不同导联的QT间期存在差异,但一直未引起临床足够重视。直至1985年Campbell等发现这些差异存在一定的规律性,从而提出了QT离散度(QTdisperson, QTd)这一概念。它的应用已涉及到QT延长综合征、缺血性心脏病,肥厚性心肌病,心功能不全和心律失常等心脏病领域。 1 概念 QT间期离散度(QTd)是指体表12导联心电图不同导联之间最长QT间期(QTmax)与最短QT间期(QTmin)的差异程度,它克服了单导联测量QT间期的局限,反映了心室肌复极化的不均一性。     

肝硬变患者QT间期延长及QT间期离散度的临床意义

目的探讨肝硬变患者QT间期及QT间期离散度 (QTd)的变化与临床意义。方法测量 13 8例病毒性肝炎肝硬变患者的同步 12导联心电图 ,分析QT间期及QTd ,并与其他消化系疾病的 5 0例住院患者进行对照。结果肝硬变患者中QT间期延长发生率非常显著高于对照组 (P <0 .0 1) ,QTd也显著高于对照组 (P <0 .0 5 ) ;肝硬变患者Child PughA、B、C3级中QT间期延长发生率逐步升高 ,QTd增加也逐渐明显 (均为P <0 .0 5 ) ;肝硬变患者中死亡者的QT间期非常显著长于存活者 ,QTd也非常显著增加 (均为P <0 .0 1)。结论肝硬变患者QT间期延长发生率高 ,QTd增加明显 ,且与肝硬变严重程度相平行。提示QT间期延长及QTd可以作为肝硬变严重程度的指标之一。     

QT间期离散度增大与室颤的联系

QT间期离散度(QTd)是指同一份常规体表心电图各导联间QT时限的变异情况,其反映心室复极状况,可作为心肌电活动稳定状况的指标之一,目前已用于预示室速室颤等恶性心律失常的发生。笔者通过20例院内发生室颤病例发作前5天内常规心电图的观察探讨QT离散度预测室颤的价值。     

QT间期离散度及其临床应用

众所周知,体表心电图上QT间期可反映整个心肌复极化过程。自1985年Campbell等首先描述了体表心电图不同导联QT间期存在微小差异以来,越来越多的证据提示,各导联间QT间期的这种离散性并不是记录的伪差,而可能是心室肌复极障碍的反映,代表不同区域心肌复极的时间差异。由此提出了QT间期离散度这一概念,指同步记录的体表12导联心电     

Impact of electrocardiogram recording format on QT interval measurement and QT dispersion assessment

The aim of this study was to determine the effect of recording conditions on the operator dependent measures of QT dispersion in patients with known and/or suspected repolarization abnormalities. Among several methods for risk stratification, QT dispersion has been suggested as a simple estimate of repolarization abnormalities. In a cohort of high and low risk patients, different components of the repolarization process were assessed in the 12-lead ECG using three different paper speeds and amplifier gains. To assess measurement error and reproducibility, a straight line was repeatedly measured. The operator error was 0.675 +/- 0.02 mm and the repeatability of the measurement error was 31 +/- 6%. The QT interval was most frequently measurable in V2-V5. Depending on the lead selected for analysis, the incidence of visible U waves was greatest in the precordial leads with high amplifier gain and low paper speed, strongly affecting QT interval measurement. The timing of the onset of the QRS complex (QRS onset dispersion) or offset of the T wave was strongly dependent on the paper speed. Paper speed, but not amplifier gain, had a significant shortening effect on the measurement of the maximum QT interval. As QT interval measurement in each ECG lead incorporates QRS onset and T wave offset (depending on the number of visible U waves), the dispersion of each of these parameters significantly affected QT dispersion. Thus, QT dispersion appears to reflect merely the presence of more complex repolarization patterns in patients at risk of arrhythmias.     

Effects of aging and gender on QT dispersion in an overtly healthy population

The objective of this study was to measure the normal variation of QT dispersion (QTd) with respect to age and gender. The QT interval is a measure of the duration of ventricular depolarization and repolarization, while the QTd is a measure of the variability of the ventricular recovery time. The QTd has been suggested as a means of identifying those patients at risk for sustained ventricular tachyarrythmias and sudden cardiac death (SCD). A total of 250 patients (120 women, 130 men; age range 20-86 years) were recruited for this study. The QT intervals were measured in each of the 12 standard leads of the electrocardiogram. Data are presented as mean (mu) +/- SD. The QTd did not vary significantly within the same gender. A significant difference (P < 0.001) was noted in QTd between men (age [mu] = 53.3 +/- 15.6 years, QTd = 0.044 +/- 0.019 s) and women (age [mu] = 52.1 +/- 15.1 years, QTd = 0.034 +/- 0.015 s). Overall, men had a greater QTd, while women had a longer QT. In conclusion, we found that men had a longer QTd, which may explain the increased risk of SCD. However, women have a longer QT interval with a smaller QTd. A longer QTmin, as opposed to a longer QTmax, is responsible for the shorter QTd in women. This longer QTmin in women may predispose to an increased risk of drug induced torsades de pointes.     

高血压左室肥厚超声心动图检查与心电图QT离散度测定的对比研究

对６８例高血压病患者进行二维超声及多普勒心脏检查，同时进行体表心电图ＱＴ离散度（ＱＴｄ）测定，旨在探讨左室肥厚和功能损伤与ＱＴｄ之间的关系。结果显示左室壁最大厚度与总厚度积分与ＱＴｄ呈正相关，ＱＴｄ与左室内径缩短分数之间无相关关系。６５％的患者存在１项或多项多普勒左室舒张功能异常指标，ＱＴｄ与左室舒张功能异常程度密切相关。提示高血压左室肥厚和功能损伤时表现有ＱＴｄ增大，说明高血压左室肥厚超声心动图特征与心电图ＱＴｄ增大产生的基质是一致的     

QT dispersion in children with ventricular arrhythmia and a structurally normal heart

In adults, increased QT dispersion has been shown to predict arrhythmic risk as well as risk of sudden death in several clinical settings. It is not known whether or not QT dispersion is increased in children with idiopathic ventricular arrhythmia. We studied three groups of children: (1) 20 patients with idiopathic VT (aged 3-18 years; mean 11.2 years); (2) 30 patients with benign PVCs (aged 1-20 years; mean 10.5 years); and (3) 30 control subjects (aged 4-17 years; mean 12 years). Standard ECGs were reviewed and the dispersion of both QT and JT intervals was compared. No patient had structural heart disease or long QT syndrome. The QT and QTc dispersion (QT delta, QTc delta) among the three groups did not differ: QTc delta of the VT group was 70 ms +/- 30 ms, QTc delta of PVC patients was 60 ms +/- 30 ms, and the QTc delta of the control group was 65 ms +/- 30 ms. The JTc delta among the three groups did not differ as well: JTc delta of the VT group was 70 ms +/- 30 ms, the JTc delta of the PVC group was 60 msec +/- 25 msec, and the JTc delta of the control group was 70 ms +/- 30 ms. We conclude that QT and JT dispersion are not significantly altered in children with idiopathic VT or benign PVCs when compared to control subjects. QT dispersion is not a reliable marker for arrhythmic risk in children with idiopathic ventricular arrhythmias and structurally normal hearts.     

852例机测QT离散度正常值分析

目的　报告计算机自动测量 QT离散度指标的正常值范围并进行简单分析。方法　采用 Marquette公司 12导联同步心电记录仪及其 QTguard系统 ,对 85 2例健康成年人的 QT离散度指标进行测定。结果　 1均值及其 95 %可信限范围分别为 :GQTd( 2 5 .2 6± 10 .3 1) ms;GQTcd:( 2 9.2 6± 13 .83 ) ms;PQTd:( 18.18± 11.2 0 ) ms;PQTcd:( 2 1.46± 13 .5 0 ) ms;PQTPd:( 2 2 .66± 12 .60 ) ;PQTPcd:( 2 4.11± 13 .5 3 ) ;GQTPd:( 2 9.79± 13 .2 2 ) ms;PQTPcd:( 3 2 .0 4± 14 .60 ) ms。 2所有指标均与年龄无关。 3心率、GQTd、GQTPd、QT存在性别差异 ,但以心率校正后则无性别差异。结论　使用校正 QT离散度指标不需要考虑性别和年龄差异     

QT dispersion from body surface ECG does not reflect the spatial dispersion of ventricular repolarization in sheep

The correlation between the QT dispersion on body surface ECG and the dispersion in ventricular repolarization from the cardiac surface was studied in six sheep anesthetized with pentobarbital. The standard 12-lead body surface ECG and multiple ventricular epicardial ECGs were simultaneously recorded. The activation-recovery interval (ARI) was measured from the unipolar epicardial ECGs. The pooled QT dispersion from the six animals was significantly smaller than the pooled ARI dispersion (22.7 +/- 2.6 vs 33.0 +/- 6.9 ms, P < 0.01). There was no correlation between the QT and ARI dispersion. The unipolar epicardial ECGs were then converted into bipolar ECGs and epicardial QT intervals were subsequently acquired from these ECGs. The average value of epicardial QT dispersion from the six animals was similar to that of body surface ECG, but was less than the ARI dispersion (27.5 +/- 6.8 vs 33.0 +/- 6.9, P < 0.01). A good correlation between the epicardial QT dispersion and ARI dispersion was identified (r = 0.84, P < 0.05). In addition, a prolongation in ventricular repolarization, induced by an increase in coronary flow, elicited a pooled ARI dispersion of 62.3 +/- 6.2 ms (n = 6), which was larger than the simultaneously recorded body surface QT dispersion (28.3 +/- 9.8 ms, n = 6, P < 0.01). No correlation between the ARI and QT dispersion was found in the presence of the prolonged ventricular repolarization. In conclusion, QT dispersion from a 12-lead body surface ECG seems to underestimate the spatial dispersion of ventricular repolarization acquired from sheep epicardium.