记录纸速及不同参数对测量QT离散度结果影响的研究

测量５５例行射频消融术（ＲＦＣＡ）患者手术前后分别以２５和５０ｍｍ／ｓ纸速所描记ＥＣＧ的ＱＴ离散度，并采用多个表达离散度的参数进行分析，旨在探讨ＥＣＧ走纸速度和采用不同参数对ＱＴ离散度结果的影响。５５例患者，男２５例，女３０例，平均年龄４５±１５岁。采用ＳｉｅｍｅｎｓＲＥＣＯＲ１２导电生理仪同步描记患者术前、术后即刻及出院后复查的１２导联心电图，手工测量ＱＴ离散度，采用七个参数进行评价：（１）ＱＴ离散度（ＱＴｄ）＝最大ＱＴ间期（ＱＴｍａｘ）－最小ＱＴ间期（ＱＴｍｉｎ）；（２）校正ＱＴ离散度（ＱＴｃｄ）＝ＱＴｃｍａｘ－ＱＴｃｍｉｎ（ＱＴｃ＝ＱＴ／ＲＲ）；（３）相对ＱＴ离散度（ＣＶ）＝ＱＴ标准差／ＱＴ均数×１００；（４）导联校正ＱＴ离散度（ａＱＴｄ）＝ＱＴｄ／测量导联数）；（５）ＱＴ间期的标准差（ＳＤ）；（６）ＪＴ离散度（ＪＴｄ）＝ＪＴｍａｘ－ＪＴｍｉｎ；（７）校正ＪＴ离散度（ＪＴｃｄ）＝ＪＴｃｍａｘ－ＪＴｃｍｉｎ。结果表明以２５ｍｍ／ｓ纸速记录ＥＣＧ测得的ＱＴ离散度参数与从５０ｍｍ／ｓＥＣＧ测得的相对应参数间显著相关，其中ＪＴ间期离散度相关性优于ＱＴ离散度，ＪＴｄ２５与ＪＴｄ５０间的相关系数为０．７４９，ＱＴ     

美托洛尔对冠心病患者QT离散度的影响

为探讨β－受体阻断剂美托洛尔（Ｍｅｔｏｐｒｏｌｏｌ）对冠心病（ＣＡＤ）患者ＱＴ离散度（ＱＴｄ）的影响，采用随机分组、单盲处理、前瞻性研究的方法，观察６２例ＣＡＤ患者Ｍｅｔｏｐｒｏｌｏｌ治疗前、后ＱＴｄ及ＲＲ间期、心率校正ＱＴ间期离散度（ＱＴｃｄ）、最大ＱＴ间期（ＱＴｍａｘ）、最小ＱＴ间期（ＱＴｍｉｎ）的变化。试验组Ｍｅｔｏｐｒｏｌｏｌ治疗后ＣＡＤ患者ＱＴｍｉｎ延长（３８６±３１．８ｍｓｖｓ３５２±２２．４ｍｓ，Ｐ＜０．０１），而ＱＴｍａｘ无明显改变（４３０±３５．６ｍｓｖｓ４２３±３４．９ｍｓ，Ｐ＞０．０５），ＱＴｄ、ＱＴｃｄ则显著缩小（分别为４４±１２．９ｍｓｖｓ７１±２８．６ｍｓ，４５±１１．５ｍｓｖｓ７９±３４．９ｍｓ，Ｐ均＜０．０１）。对照组治疗前、后ＱＴｄ、ＱＴｃｄ、ＱＴｍａｘ、ＱＴｍｉｎ均无改变（Ｐ＞０．０５）。表明Ｍｅｔｏｐｒｏｌｏｌ通过显著延长ＣＡＤ患者的ＱＴｍｉｎ缩小心肌复极化离散的程度，使心肌复极化趋向同步，这有利于防止恶性室性心律失常的发生     

QT离散度与冠心病的关系

根据１３２例患者冠脉造影（ＣＡＧ）结果，结合临床诊断进行分组并分别从体表静息标准１２导联心电图上测量得出ＱＴ间期离散度（ＱＴｄ）与ＱＴｃ间期离散度（Ｑｔｃｄ）。统计学处理结果显示：ＱＴｄ、ＱＴｃｄ在冠脉正常组（Ｃ组）分别是２２．７±１９．７ｍｓ与２８．０±１５．９ｍｓ，冠脉病变组（Ｂ组）分别是３６．４±１６．６ｍｓ与４１．０±１７．５ｍｓ，与前组比较有显著差异（Ｐ＜０．０１）。急性心肌梗死组（Ａ组）ＱＴｃ、ＱＴｃｄ分别是６４．８±２５．４ｍｓ、７３．１±２９．４ｍｓ，与前两组比较均有明显差异（Ｐ＜０．０１）。结果显示：不但急性心肌梗死组ＱＴｄ增大，而且冠脉病变组ＱＴｄ也增大。故认为心肌缺血是ＱＴｄ增大的重要原因之一，且可能与缺血产生速度和严重程度有关。     

QT离散度及其相关指标的年龄性别差异

目的 报告ＱＴ离散度及其相关指标的年龄性别差异。方法 记录５０４例健康成人的体表１２导联同步心电图,按性别分组,男性２５０例,女性２５４例,按年龄分组,１８－２９岁组１２８例,３０－３９岁组１２８例,４０－４９例组１２１例,５０－６０岁组１２７例,比较ＱＴ离散度及其相关指标的年龄、性别差异 。结果 １．男性各参数离散度大于女性;ＱＴｄ,ＱＲＳｄ,ＯＱＴｄ,ＪＴｄ,Ｔｐ－Ｔｅｄ,ＪＴｐｄ,Ｑｔｐｄ,     

正常人QT离散度测量的重复性

目的：观察不同方法测量ＱＴ离散度的重复性和误差大小。方法：用５０ｍｍ／ｓ纸速１２导同步心电图机和２５ｍｍ／ｓ纸速三导同步心电图机同时启示２０例正常人的心电图，采用ＱＴｄ，ＱＴｃｄ，ＱＴａｄ，ＪＴｄ，ＪＴｃｄ，ＪＴａｄ六个指标进行ＱＴ离散度分析。结果：由５０ｍｍ／ｓ纸速１２导联同步心电图测得的ＱＴ离散度，ＪＴ离散度的相对误差在两位测量者之间分别为１２－１３％与１４－１５％，在同一测量者两次之间的分别     

对QT离散度实质的探讨

为探讨ＱＴ离散度（ＱＴｄ）的真实意义，观察１３９例急性心肌梗死（ＡＭＩ，ＡＭＩ组）及１０９例正常人（对照组）的最长ＱＴ间期（ＱＴｍａｘ）、校正ＱＴｍａｘ（ＱＴｃｍａｘ）及ＱＴｄ的变化。结果：①ＡＭＩ组的ＱＴｍａｘ、ＱＴｃｍａｘ和ＱＴｄ均显著高于对照组（分别为４２２．６０±３０．５１ｍｓｖｓ３８２．４６±２３．４０ｍｓ、４６０．２１±２８．９６ｍｓｖｓ３８８．５１±２０．１５ｍｓ、５９．８０±２８．４０ｍｓｖｓ３９．４３±１２．２１ｍｓ，Ｐ均＜０．００１）。②ＡＭＩ组中发生严重室性心律失常（ＶＡ）患者（１１４例）的ＱＴｍａｘ、ＱＴｃｍａｘ、ＱＴｄ与无ＶＡ的患者（２５例）相比，均有显著差异（分别为４４８．５８±３３．４０ｍｓｖｓ４１６．１０±３５．３０ｍｓ、４８１．４３±３５．１７ｍｓｖｓ４３９．６０±２７．１０ｍｓ、６６．９０±２０．７２ｍｓｖｓ４８．３２±２３．６１ｍｓ，Ｐ均＜０．００１）。认为ＡＭＩ时ＱＴｄ系Ｔ向量环在不同导联上的“投影”差异所引起的，其异常的本质是ＱＴ间期延长     

QT离散度的应用及评价

ＱＴ离散度（ＱＴｄ）系指心电图各导联间 ＱＴ时限变异的程度,定义为１２导联心电图最长ＱＴ间期（ＱＴｍａｘ）与最短ＱＴ间期（ＱＴｍｉｎ）的差值;有实测和心率校正两种ＱＴｄ值,即 ＱＴｄ和校正的 ＱＴｄ（ ＱＴｃｄ）;由于ＱＴ间期受室内传导时间的影响,故有人主张采用ＪＴ离散度（ＪＴｄ）和校正的ＪＴｄ（ＪＴｃｄ）;方法从采用非同步心电图采样和目测法,转为采用１２导联同步心电图机采样和计算机软件分析。 应用体表心电图测定 ＱＴｄ最早由 Ｃａｍｐｂｅｌｌ等于 １９８５年提出,１９９０年Ｄａｙ等首次证实其具有重要的…     

冠心病与心肌肥厚QT间期离散度的临床意义

目的 对比ＱＴ间期离散度（ＱＴｄ）的报警指标，对预测冠心病与有心肌肥厚的各类心脏病发生危险性心律失常及猝死的差异。方法 选择正常对照组（Ａ组）、冠心病组（Ｂ组）和各类有心肌肥厚的心脏病组（Ｃ组）各３０例，随访１年，记录标准１２导联心电图，分析其心电图校正后的ＱＴｄ（ＱＴｃｄ）与室性心律失常猝死率的关系。结果 Ａ组ＱＴｃｄ（４２±１５）ｍｓ与Ｂ组、Ｃ组的ＱＴｃｄ（６６±１２￣８１±１４）ｍｓ均有显     

健康国人QTU是期离散度的检测及其相关因素分析

目的 建立健康国人１２导联同步心电图ＱＴ间期离散度平均值及相关因素分析。方法 对１￣８７（３９．４±１７．３）岁健康国人２０７８例,用广东中山ＳＲ－１０００Ａ心电综合自动分析仪采集１２导联同步体表心电图数据并录入软盘,专人在显示顺上进行回放分析。增益放大１ｍＶ＝２０￣４０ｍｍ,纸速放大５０￣１００ｍｍ／ｓ。测量ＱＴｍａｘ、ＱＴｍｉｎ按Ｂａｚｅｔｔ公式校正ＱＴｃｍａｘ、ＱＴｃｍｉｎ,计算ＱＴｄ（ＱＴ     

正常成人QTmax,QTmin在十二导心电图的分布规律及临床意义

目的 找出正常成人最大ＱＴ间期（ＱＴｍａｘ）和最小ＱＴ间期（ＱＴｍｉｎ）在十二导心电图的分布规律,提高ＱＴ离散度的敏感性。方法 在５８２例正常成人进行十二导心电图同步记录检查,找出ＱＴｍａｘ和ＱＴｍｉｎ在各导联的数量和在十二导心电图中的分布规律,统计各导联缺失和不同导联组合缺失时的ＱＴ离散度均值,观察其对ＱＴｄ的影响。结果 ５８２例心电图平均ＱＴｄ３５．３±９．５ｍｓ,各导联ＱＴ间期均值ａｖＬ最小     

QT Dispersion Increases with Aging

Background: Age‐related changes in cardiovascular system are well‐known. Arrhythmias in elderly patients constitute most of the urgencies, consultations, or hospitalizations. QT dispersion (QTd) is a simple noninvasive arrhythmogenic marker to demonstrate the electrical instability of the heart. The aim of this study was to investigate how QTd changes with increasing age by calculating the QTd in the elderly and younger subjects. Methods: One hundred and forty‐six consecutive subjects (62 males and 84 females; age range: 18–82 years) were enrolled in the study. Sixty‐seven of the subjects were 65 years and over (mean age, 70 ± 4), 79 were younger than 65 (mean age, 37 ± 11). A 12‐lead ECG was recorded. The longest and the shortest QT intervals were measured manually on these ECG recordings. QTd was calculated from the formula, QTd = QTmax ? QTmin. Results: Demographic features were similar between the two groups. QTd of the elderly group was found to be significantly higher than the younger group (35.6 ± 15.6 in elderly, 24.2 ± 12.4 in younger group, P < 0.001). A positive relationship was found between QTd and age (r = 0.415, P < 0.001). QTd was greater in female than in male (31.9 ± 16.7 ms vs 26.0 ± 11.3 ms, respectively, P = 0.018). Conclusions: Our study shows that QTd increases with advancing age. We think that long‐term follow‐up of these patients would be useful to show if there is any relationship between the clinical outcomes and the increase in QTd.     

Dispersion of the QT Interval in Subjects with Frequent Nonsustained Ventricular Arrhythmias and No Underlying Heart Disease: Arrhythmogenic Substrate or Mechanoelectrical Feedback of Arrhythmias?

Background: QT dispersion (QTd) on the ECG is thought to reflect the temporal and spatial inhomogeneity of repolarization in the underlying myocardium. In myocardial infarction, ischemia, and long QT syndromes, an increased QTd is associated with a propensity for malignant ventricular arrhythmias and sudden cardiac death. We investigated this feature of the repolarization process in subjects with frequent ventricular arrhythmias and structurally normal hearts. Methods: Forty‐nine patients referred for frequent, nonsustained ventricular arrhythmias (45 ± 14 years, ×± SD, 61% female) had normal ventricular dimensions and function, no late potentials, and normal ECG. They were compared with 30 controls (42 ± 13 years, 50% female). QTd was measured as the difference between the longest and the shortest QT in the six precordial leads at a paper speed of 50 mm/s. Results: In patients, QTc was similar to that of controls: 395 ± 21 versus 386 ± 20. However, QTd was greater: 49 ± 20 ms versus 32 ± 14 ms, P < 001. Moreover, 18 patients (36%) had QTd exceeding 60 ms—a value superior to the mean normal value of 2 SD—compared to only 1 control (3%) (P < 0.01). Finally, patients with more frequent ventricular arrhythmias had larger QTd. Conclusions: In patients with frequent nonsustained ventricular arrhythmias and otherwise normal hearts, QT interval dispersion is increased. We speculate that, instead of representing a specific electrophysiological substrate of arrhythmias, QT dispersion in this specific population could result from arrhythmias themselves through a possible mechanoelectrical feedback.     

Global T-wave inversion: limited QT dispersion despite QTc prolongation--a correlate of benignity in patients with strikingly abnormal electrocardiograms.

BACKGROUND: The global T-inversion (GTI) electrocardiogram (ECG) is strikingly abnormal with major QTc prolongation, but with a surprisingly good prognosis by Kaplan-Meier curve. This contrasts with most significant QTc prolongations. HYPOTHESIS: This study was undertaken to ascertain QT interval dispersion (QTd) in global T wave inversion, a clinically benign long QTc ECG. METHODS: Longest and shortest QT intervals in all 12 leads in 35 consecutive patients with GTI were determined by two mutually blinded observers. QTd was determined by subtraction (maximum-minimum) and QTc was calculated using the Bazett formula. RESULTS: There was a 2:1 female preponderance QTc was prolonged and equal for men (0.471) and women (0.469). Observer variability of under 2% permitted averaging of QT measurements. Composite mean QTd was 55 ms. The literature revealed a range of QTd in normal subjects of 39 to 59 ms (mostly 49 to 59 ms). Patient series with abnormal QTd were well above this level. CONCLUSION: Despite a strikingly abnormal ECG with marked QTc prolongation, QT dispersion was limited in global T inversion, consistent with its previously demonstrated benignity.     

Evaluation of Tp-e interval and Tp-e/QT ratio in patients with non-dipper hypertension

Aims: Non-dipper hypertension is associated with increased cardiovascular morbidity and mortality. Several studies have suggested that the interval from the peak to the end of the electrocardiographic T wave (Tp-e) may correspond to the transmural dispersion of repolarization and that increased Tp-e interval and Tp-e/QT ratio are associated with malignant ventricular arrhythmias. The aim of this study was to evaluate ventricular repolarization by using Tp-e interval and Tp-e/QT ratio in patients with non-dipper hypertension.

Materials and method: This study included 80 hypertensive patients. Hypertensive patients were divided into two groups: 50 dipper patients (29 male, mean age 51.5?±?8 years) and 30 non-dipper patients (17 male, mean age 50.6?±?5.4 years). Tp-e interval and Tp-e/QT ratio were measured from the 12-lead electrocardiogram. These parameters were compared between groups.

Results: No statistically significant difference was found between two groups in terms of basic characteristics. In electrocardiographic parameters analysis, QT dispersion (QTd) and corrected QTd were significantly increased in non-dipper patients compared to the dippers (39.4?±?11.5 versus 27.3?±?7.5?ms and 37.5?±?9.5 versus 29.2?±?6.5?ms, p?=?0.001 and p?=?0.01, respectively). Tp-e interval and Tp-e/QT ratio were also significantly higher in non-dipper patients (97.5?±?11.2 versus 84.2?±?8.3?ms and 0.23?±?0.02 versus 0.17?±?0.02, all p value <0.001).

Conclusion: Our study revealed that QTd, Tp-e interval and Tp-e/QT ratio are prolonged in patients with non-dipper hypertension.     

Relation between Beat‐to‐Beat QT Interval Variability and T‐Wave Amplitude in Healthy Subjects

Objectives: Elevated beat‐to‐beat QT interval variability (QTV) has been associated with increased cardiovascular morbidity and mortality.The aim of this study was to investigate interlead differences in beat‐to‐beat QTV of 12‐lead ECG and its relationship with the T wave amplitude. Methods: Short‐term 12‐lead ECGs of 72 healthy subjects (17 f, 38 ± 14 years; 55 m, 39 ± 13 years) were studied. Beat‐to‐beat QT intervals were extracted separately for each lead using a template matching algorithm. We calculated the standard deviation of beat‐to‐beat QT intervals as a marker of QTV as well as interlead correlation coefficients. In addition, we measured the median T‐wave amplitude in each lead. Results: There was a significant difference in the standard deviation of beat‐to‐beat QT intervals between leads (minimum: lead V₃ (2.58 ± 1.36 ms), maximum: lead III (7.2 ± 6.4 ms), ANOVA: P < 0.0001). Single measure intraclass correlation coefficients of beat‐to‐beat QT intervals were 0.27 ± 0.18. Interlead correlation coefficients varied between 0.08 ± 0.33 for lead III and lead V₁ and 0.88 ± 0.09 for lead II and lead aVR. QTV was negatively correlated with the T‐wave amplitude (r =–0.62, P < 0.0001). There was no significant affect of mean heart rate, age or gender on QT variability (ANOVA: P > 0.05). Conclusions: QTV varies considerably between leads in magnitude as well as temporal patterns. QTV is increased when the T wave is small.     

QT Interval Length and Diabetic Autonomic Neuropathy

QT interval length was measured in ECG recordings from three groups of age-matched male subjects: 36 normal subjects, 41 diabetic patients without (DAN-ve), and 34 with (DAN+ve) autonomic neuropathy. ECG samples were selected from previously recorded 24-h ECGs on the basis of a clearly defined T wave and a steady RR interval over 2 min of around 750 ms (80 beats min^?1). There were no significant differences in RR interval between the groups. The two diabetic groups had slightly longer QT measurements (normal 365 ± 14 (±SD) ms, DAN-ve 373 ± 18 ms, DAN+ve 375 ± 23 ms, p = 0.05), and corrected QT (QTc) values (normal 423 ± 15 ms, DAN-ve 430 ± 20 ms, DAN+ve 435 ± 24 ms, p = 0.05). Ten diabetic patients fell above our defined upper limit of normal for QTc (>mean + 2SD). There was a significant correlation in the DAN-ve group between the QT indices and 24-h RR counts (QT r = ?0.38, p < 0.01; QTc r = ?0.40, p < 0.01). We conclude that there are some small alterations in QT interval length in the steady state in diabetic autonomic neuropathy. The changes appear to be due to autonomic impairment, rather than diabetes per se.     

心肌梗死患者QTd、Tp-Te和Tp-Te/QT的观察

目的观察心肌梗死后3~6个月患者心电图QTd、Tp-Te和Tp-Te/QT与对照组之间有无差异。方法选取自2011年1月至9月行心电图检查的心梗后3~6个月患者30例,男14例,女16例,平均年龄(51.2±11.94)岁;收集年龄、性别相匹配的对照组30例,男15例,女15例,平均年龄(50.4±9.45)岁,测量各组心电图QTd、Tp-Te间期并计算Tp-Te/QT值。结果心梗组Tp-Te和Tp-Te/QT比值均大于对照组,差异具有统计学意义(心梗组Tp-Te:101.9±14.5ms;Tp-Te/QT:0.287±0.04;对照组Tp-Te:75.7±12.4ms;Tp-Te/QT:0.193±0.03;p<0.05);QTd在两组之间无差异(心梗组:40.5±3.9ms;对照组:37.9±3.8ms;p>0.05)。结论心梗患者Tp-Te,Tp-Te/QT比值增高,可反映跨室壁复极离散度的变化,与心律失常的发生关系密切。     

Effect of balloon inflation-induced acute ischemia on QT dispersion during percutaneous transluminal coronary angioplasty

Background: QT dispersion (QTd = QT_max - QT_min) measured as interlead variability of QT interval reflects the spatial inhomogeneity of ventricular repolarization times, and increased QTd may provide a substrate for malignant ventricular arrhythmias. Ischemia is associated with regional abnormalities of conduction and repolarization. Hypothesis: This study aimed to investigate the effect of acute ischemia on QTd during successful percutaneous transluminal coronary angioplasty (PTCA). Methods: Forty-three patients (10 women, 33 men, mean age 56 years) were enrolled in the study. Electrocardiogram (ECG) recordings were taken before PTCA and during balloon inflation period. QT maximum (QT_max), QT minimum (QT_min), and QTd (QT_max - QT_min) values were calculated from the surface ECG. Results: There was no difference among QT_max values (p = 0.6). Mean QT_min during balloon inflation was lower than before PTCA (368 ± 45 vs. 380 ± 41 ms, p = 0.002). The difference between QTd values before and during balloon inflation was statistically important (65 ± 9 vs. 76 ± 10 ms, p = 0.001). This difference is caused by a decrease in QT_min during balloon inflation. Conclusion: Acute reversible myocardial ischemia induced by balloon inflation causes an increase in QTd value, and this increment is the result of a decrease in QT_min interval. Therefore, QTd may be a marker of reversible myocardial ischemia.     

QT间期及其离散度与冠状动脉病变的关系

探讨心电图QT间期、QT离散度 (QTd)与冠状动脉病变及其程度和范围的关系。分析 138例行选择性冠状动脉造影病例的临床及心电图资料 ,观察不同程度和范围的冠状动脉病变对QT指标的影响。结果 :无冠状动脉狭窄病人的QTd为 42 .0± 18.2 4ms,单支病变组及多支病变组的QTd分别为 48.42± 17.11,5 9.15± 2 2 .75ms ,P均 <0 .0 5 ;轻度狭窄组及重度狭窄组的QTd分别为 48.6 7± 2 0 .45 ,5 8.12± 2 1.6 1ms ,P均 <0 .0 5。结论 :QTd延长有助于心肌缺血的诊断 ,并可能反映冠状动脉病变的范围及程度