急性心肌梗死患者静脉溶栓对QT间期离散度的影响

目的探讨急性心肌梗死(AM I)患者静脉溶栓对QT间期离散度(QTd)的影响。方法34例AM I患者分为溶栓再通组,未通组及非溶栓组,测定其溶栓前后的QTd,并与非溶栓组QTd比较。结果AM I患者溶栓前QTd溶栓组(83.28±11.15)ms,与非溶栓组(84.25±11.23)ms,两组差异无显著性(P>0.05),溶栓治疗再通后,QTd明显减少。溶栓未通组及非溶栓组(48.43±7.12)ms,(49.11±8.29)ms,显著高于溶栓再通组(39.21±6.23)ms(P<0.05),室性心动过速(VT),心室颤动(VF)及猝死组(95.81±9.52)ms的QTd明显长于无VT,VF及非猝死者(75.97±9.33)ms(P<0.05)。结论急性心肌梗死静脉溶栓再通后,随心肌缺血改善,QTd明显改善,室性快速心律失常发生率降低。     

早期溶栓治疗对急性心肌梗死患者QT间期离散度的影响

目的 :探讨早期溶栓治疗对急性心肌梗死患者QT间期离散度的影响。方法 :116例AMI患者 ,溶栓再通组 3 6例 ,未通组 16例 ,非溶栓组 64例 ,比较 3组QTd。结果 :溶栓再通组QTd值明显减少 ,未通组及非溶栓组QTd值增大 ,且后两组QTd值比较差异无显著性 (P >0 0 5 )。QTd增大者发生室性快速心律失常比率增大。结论 :溶栓再通后AMI患者QTd值明显降低 ,同时室性快速心律失常发生率降低     

急性心肌梗死早期及溶栓后QT离散度的测定与心律失常关系

目的　急性心肌梗死 (AMI)患者溶栓前后QT离散度测定与心律失常的关系。方法　将 6 7例AMI患者中有心律失常的 30例分为心律失常组 ,37例无心律失常分为对照组 ,测定溶栓前后QT离散度。结果　AMI心律失常组与对照组间QTd差异有极显著性 (94 8± 9 2msvs 6 6 .32± 12 2ms,P <0 0 1) ,溶栓后QTd降至 6 8 3± 8 8ms,心律失常消失。结论　成功的溶栓可使QTd显著下降 ,减少危险心律失常的发生。     

老年急性心肌梗死患者溶栓治疗对QT离散度的影响

观察 5 6例老年急性心肌梗死患者静脉溶栓前后QT离散度的变化。结果显示 ,溶栓再通组QT离散度较溶栓未通组QT离散度显著减少 ,差异有显著性 (P <0 0 1) ,且再通组QT离散度与溶栓前比较差异有显著性 (P <0 0 1) ,而溶栓未通组其溶栓前后QT离散度值差异无显著性 (P >0 0 5 )。因此 ,QT离散度可作为溶栓再灌注的参考指标之一。     

急性心肌梗死患者溶栓前后QT离散度的变化

目的:观察急性心肌梗死(AMI)患者溶栓前后QT离散度(QTdispersion,QTd)的变化及早期再灌注对QTd的影响。方法:对61例AMI患者给予尿激酶静脉溶栓治疗,予溶栓前及溶栓2h后同步记录18导联心电图,分别测量成功组及失败组的QTd,并进行前后比较。结果:溶栓后再通41例,溶栓后未通20例。血管未通组其QTd较前减少,但无统计学意义(P>0.05),溶栓后再通组其QTd较血管未通组降低程度更大,有统计学意义(P<0.01)。结论:QTd可作为评价AMI患者溶栓后判断溶栓成功与否的一项临床早期参考指标。     

急性心肌梗死静脉溶栓治疗对QT离散度的影响

目的 :探讨急性心肌梗死溶栓治疗对QT离散度及近期预后的影响。方法 :观察急性心肌梗死发病 12h内接受静脉溶栓治疗的 78例患者 ,按溶栓后冠脉有无再通分为再通组 (5 0例 )和未再通组 (2 8例 ) ,测定溶栓治疗前后QT离散度 (QTd)、校正的QT离散度 (QTcd) ,并观察两组恶性室性心律失常的发生情况。结果 :溶栓前两组Q T离散度无差异 ,溶栓后QT离散度再通组明显低于未再通组 (P <0 0 5 ) ,恶性室性心律失常溶栓前再通组与未再通组差异无显著意义 (P >0 0 5 ) ,溶栓后再通组显著低于未再通组 (P <0 0 1)。结论 :急性心肌梗死行有效的静脉溶栓治疗可缩短QTd、QTcd ,改善心肌电稳定性 ,并减少恶性室性心律失常的发生。     

溶栓治疗对急性心肌梗死患者QT离散度的影响

目的:探讨急性心肌梗死(AMI)患者静脉溶栓前后QT离散度(QTd)变化及其对预后的影响.方法:105例AMI患者分为溶栓再通组、未通组和未溶栓组.测定其溶栓前及溶栓治疗1、2周后QTd变化,并与未溶栓组比较.同时比较三组治疗2周时高危室性心律失常.结果:溶栓治疗再通治疗1、2周后QTd显著缩小(P皆＜0.01),高危室性心律失常的发生率低,其与未通组和未溶栓组比较,差异皆有显著性(P＜0.01).而未通组、未溶栓组治疗前后QTd变化和高危室性心律失常的发生率皆无差异(P＜0.05).结论:AMI后2周内QTd增大者,其溶栓再通的可能性小,发生高危室性心律失常的可能性增大.     

窦性心动过缓患者阿托品试验前后QTd变化

目的　探讨迷走神经对QT间期离散度的影响。方法　观察 12 2例窦性心动过缓者阿托品试验前后QTd和QTcd的变化。结果　注射阿托品后 3分钟内单纯窦性心动过缓组QTd和QTcd虽然缩短 ( 19.72± 12 .82ms对 2 5 .99± 10 .33ms ;17.5 4± 10 .18ms对 2 2 .84± 11.34ms) ,但无统计学差异 (P >0 .0 5 ) ;急性胆囊炎组明显缩短 ( 16 .6 6± 10 .0 0ms对2 8.89± 13.33ms ,P <0 .0 5 ;15 .0 9± 11.18ms对 2 4.35± 8.92ms ,P <0 .0 1) ;胆囊炎并缺血性心脏病组则显著延长 ( 6 6 .9± 14 .18ms对 2 9.78± 12 .5 4ms ;6 4.2 1± 15 .0 6ms对 2 6 .10± 10 .10ms ,P <0 .0 5 )。结论　提示迷走神经兴奋对缺血性心肌具有保护作用。     

再灌注治疗对急性心肌梗死患者QT离散度的影响

[目的]观察急诊冠状动脉介入术(PCI)和静脉溶栓对急性心肌梗死(AMI)患者QT离散度(QTd)的影响.[方法]127例患者分成PCI组、静脉溶栓再通组、静脉溶栓未通组及未再灌注治疗组,在再灌注治疗前及治疗后2、12、24 h、2～7d测量QTd并进行对照.[结果]PCI组及静脉溶栓再通组与静脉溶栓未通组及未再灌注治疗组QTd差异有显著性(P＜0.01),PCI组与静脉溶检再通组QTd差异无显著性(P＞0.05),静脉溶栓未通组与未再灌注治疗组QTd差异无显著性(P＞0.05).[结论]再灌注治疗成功可使AMI患者QTd显著降低.     

急性心肌梗塞溶栓前后测定QT离散度的临床价值

对41例急性心肌梗塞（AMI）患者行静脉溶栓治疗，分别测定其溶栓治疗前后QT离散度（QTd），探讨QTd在判断急性心肌梗塞溶栓治疗疗效的临床应用价值。结果：溶栓成功血管再通组25例溶栓前QTd为78．10±21．62ms，溶栓后QTd为41．20±18．23ms，两者比较差异非常显著（P＜0．01）；溶栓失败血管未通组16例溶栓前QTd为79．10±22．31ms，溶栓后QTd为74．20±21．56ms，两者比较差异无显著性（P＞0．05）。作者认为：AMI溶栓后QTd的变化可作为临床判定溶栓疗效的一项无创性指标。     

Effects of adrenaline and potassium on QTc interval and QT dispersion in man

BACKGROUND: Hypoglycaemia alters cardiac repolarization acutely, with increases in rate-corrected QT (QTc) interval and QT dispersion (QTd) on the electrocardiogram (ECG); such changes are related to the counterregulatory sympatho-adrenal response. Adrenaline produces both QTc lengthening and a fall in plasma potassium (K+) when infused into healthy volunteers. Hypokalaemia prolongs cardiac repolarization independently however, and therefore our aim was to determine whether adrenaline-induced repolarization changes are mediated directly or through lowered plasma K+. MATERIALS AND METHODS: Ten healthy males were studied on two occasions. At both visits they received similar l-adrenaline infusions but on one occasion potassium was also administered; infusion rates were adjusted to maintain circulating K+ at baseline. The QTc interval, QTd, peripheral physiological responses and plasma adrenaline and potassium concentrations were measured during both visits. RESULTS: The QTc interval and QTd increased both with and without potassium clamping. Without K+ replacement, mean (SE) QTc lengthened from 378 (5) ms to a final maximum value of 433 (10) ms, and QTd increased from 36 (5) ms to 69 (8) ms (both P < 0.001). During K+ replacement, QTc duration at baseline and study end was 385 (7) ms and 423 (11) ms, respectively (P < 0.001), and QTd 38 was (4) ms and 63 (5) ms (P = 0.001). CONCLUSIONS: These data suggest that disturbed cardiac repolarization as a result of increases in circulating adrenaline occurs independently of extracellular potassium. A direct effect of adrenaline upon the myocardium appears the most likely mechanism.     

Prevalence of Q-T interval dispersion in type 1 diabetes and its relation with cardiac ischemia : the EURODIAB IDDM Complications Study Group

OBJECTIVE: The interlead variation in duration of the Q-T interval on the surface electrocardiogram (Q-T interval dispersion [QTd]) has been shown to predict mortality in type 2 diabetic patients. We evaluated the prevalence of QTd prolongation in the EURODIAB population and its relation to corrected Q-T interval (QTc), sex, age, duration of diabetes, blood glucose control, and complications. RESEARCH DESIGN AND METHODS; A total of 3,042 type 1 diabetic patients were studied. QTc was calculated according to the Bazett's formula; QTc > 0.44 s was considered abnormally prolonged. QTd was calculated using the difference between the maximum and the minimum QTc in any thoracic lead. QTd >0.080 s was considered abnormally prolonged. RESULTS: The prevalence of an increased QTd was 7%. A significant relation was observed between QTd prolongation and diastolic blood pressure (P < 0.05). A higher prevalence of QTd prolongation was observed in patients with ischemic heart disease (P = 0.004), whereas no relationship was observed with retinopathy, albumin excretion rate, or measures of somatic and autonomic neuropathy. QTc and QTd were significantly related (P = 0.001); however, a proportion of patients with normal QTd showed a prolonged QTc (>0.44 s). CONCLUSIONS: In patients with type 1 diabetes, QTd is associated with ischemic heart disease and diastolic blood pressure but not neuropathy. Although QTd is statistically related to duration of QTc, increased QTd and increased QTc identify different patients, and their predictive value deserves prospective evaluation.     

食管心房超速负荷试验中QT间期离散度变化对冠心病的诊断价值

目的探讨食管心房超速负荷试验的QT间期离散度 (QTd)对冠心病的诊断价值。方法对冠脉造影确诊为冠心病 38例及冠脉造影正常 4 0例进行食管心房超速负荷试验 ,记录试验前后 12导联心电图 ,测量ST段 ,校正QTc及QTd ,利用四格表法 ,分别计算各指标的特异性及敏感性。结果冠心病组试验后QTc及QTd均较试验前明显延长 (P<0 .0 1) ,试验后冠心病组QTd也长于非冠心病组 (P <0 .0 5 )。ST段 ,QTc及QTd诊断冠心病的特异性分别为 95 % ,6 7.5 % ,87.5 % ,敏感性分别为 5 2 .6 % ,73.7% ,84 .2 %。结论食管心房超速负荷试验的QT间期离散度 (QTd)能增加冠心病的诊断敏感度 ,对冠心病具有较高的诊断价值。     

老年原发性高血压患者晨峰现象与心血管事件

目的探讨老年原发性高血压患者血压晨峰（MBPS）对心率变异性（HRV）及心脏结构和功能损害的影响。方法老年原发性高血压患者164例,根据24小时动态血压监测（24ABPM）分为MBPS组（90例）和非MBPS组（74例）,常规检查动态心电图、心电图、超声心动图。分析HRV时域参数大小,测量计算QT间期、校正的QT间期（QTc）、QT离散度（QTd）和校正的QT离散度（QTcd）,测定左心室舒张末期内径（LVEDd）、舒张末期室间隔厚度（ZVST）、舒张末期左心室后壁厚度（LVPWT）及左心室质量指数（LVMI）。结果MBPS组的HRV时域指标均显著低于非MBPS组,包括项目24小时全程全部窦性R—R间期平均值的标准差（SDNN）（76．1±16．9）msvs（106．1±25．6）ms;24小时内每5分钟时段窦性R—R间期平均值的标准差（SDANN）（64．6±22．3）msvs（94．7±27．0）ms;全程全部窦性R—R同期的平方根（RMSSD）（23．2±13．2）mSVS（33．8±19．5）ms;两个相邻R—R间期互差〉50ms的心跳数所占分析信息间的期内心搏数的百分比（PNN50）（3．0±2．5）％vs（7．2±6．9）％（均P〈0．01）。MBPS组的QT间期、QTc、QTd、QTcd指标高于非MBPS组,QT（381．0±28．5）ms vs（360．0±25．9）ms;QTc（413．0±31．9）ms vs（403．0±29．0）ms;QTd（35．5±12．1）ms vs（32．2±10．2）ms;QTcd（40．2±5．9）ms vs（38．4±4．1）ms（均P〈0．05）．MBPS组LVMI、LVEDd、LVST及LVPWT均高于非MPBS组（均P〈0．01）。结论老年原发性高血压患者晨峰使心血管事件的风险增加。     

QT Interval and QT Dispersion Measured with the Threshold Method Depend on Threshold Level

Various computerized methods with multiple parameter options for measurements of the QT interval now are available. The optimum parameter setting for most algorithms is not known. This study evaluated the influence of the threshold level applied on the T wave differential on the QT interval and its dispersion measured in normal and abnormal electrocardiograms (ECGs). Seven hundred sixty ECGs recorded in 76 normal subjects and 630 in 63 patients with hypertrophic cardiomyopathy (HCM) (10 consecutive recordings in each individual) were analyzed. In each lead of each ECG, the QT interval was measured by the threshold method applied to the first differential of the T wave. The threshold level was varied between 5% and 30% of the T wave maximum in 1% steps, resulting in 26 different choices of QT measurements. With each choice the maximum QTc and the QT dispersion (QTd, standard deviation of the QT in all 12 leads) were obtained for each recording. The maximum QTc was significantly longer in HCM patients than in normal subjects (P < 0.001) at all threshold levels except between 5% and 7%. The QTd was significantly greater in HCM patients at all threshold levels. The QTc and QTd changed significantly with the threshold level. The maximum QTc varied up to 60 ms in normal subjects and up to 70 ms in HCM patients, depending on the threshold level. Thus, the QT intervai and its dispersion measured with the threshold method applied to the first T wave differential depended significantly on the threshold level in both normal and diseased hearts. All programmable options of available automatic instruments should be examined carefully before any study, and all algorithmic details should be systematically presented.     

肥厚型心肌病QT离散度的临床意义及卡维地洛对其作用

目的探讨肥厚型心肌病QT离散度的临床意义及卡维地洛对其的作用。方法入选48例患者,根据超声结果将患者分梗阻性20例（梗阻组）争非梗阻28例（非梗阻组）,正常对照组20例。为每个患者记录体表常规12导联同步心电图,分别计算QT、QT离散度（QTd）、校正的QT离散度（QTcd）。在治疗过程中给予卡维地洛,在给药前、1个月和3个月后复查以上指标。结果梗阻性肥厚型心肌病和非梗阻性肥厚型心肌病QT、QTd、QTcd均超过正常值（P〈0.01）;卡维地洛能明显缩短两组的QTd,且梗阻组QTd的变化程度较非梗阻组更显著,用药前（84.2±27.1）ms vs（46.5±20.7）ms,用药3个月后（49.8±19.2）ms vs（41.3±16.3）ms（P〈0.05或〈0.01）。结论两组肥厚型心肌病QT、QTd、QTcd均超过正常值,卡维地洛能明显缩短两组的QTd,且梗阻组QTd的变化程度较非梗阻组更显著,有利于改善患者预后。     

Correlation of Heart Rate Variability Parameters and QT Interval in Patients After PTCA of Infarct Related Coronary Artery as an Indicator of Improved Autonomic Regulation

The purpose of this study was to determine if PTCA of the infarct related coronary artery (IRA) in the late phase of myocardial infarction (MI) can improve autonomic regulation of sinus rhythm and electrical stability of the myocardium measured by heart rate variability (HRV), QT, QTc, and its dispersion (QTd) and if any correlation exists among these measures. The study was performed in 25 patients (21 male, age: 50 ± 9 years, EF: 52%± 11%) in the late phase of MI (2.5 ± 1.5 months). HRV parameters were calculated automatically. QT, QTc, and QTd were measured manually from a 12-lead surface ECG (50 mm/s). All measurements were made before and 3–5 days after PTCA. Day and night parameters of HRV were sampled over two periods: 2 pm to 10 pm (day) and 10 pm to 6 am (night). Parameters of HRV measured from whole recordings were significantly higher after successful PTCA: SDRR (116 31 vs 128 ± 38 ms), SD (55 ± 17 vs 62 ± 22 ms), rMSSD (30 ± 13 vs 36 ± 14 ms) and HF (246 ± 103 vs 417 ± 224 ms2). Significant differences were found during daytime for SD, rMSSD, and HF, and during nighttime for SDRR, SDANN. QT interval duration, QT corrected to the heart rate, and QT dispersion were significantly lower after PTCA (QTd: 54 ± 15 vs 39 ± 12 ms). There was no correlation between HRV and QT values before PTCA. High correlations were found after the procedure, particularly between QTd and nighttime HRV. Conclusions: PTCA of IRA in the late phase of MI enhances sympathovagal regulation of the cardiac rhythm and the electrical stability of the heart, which may be prognostically important.     

QT interval dispersion in ventricular beats: a noninvasive marker of susceptibility to sustained ventricular arrhythmias

Increased QT dispersion (QTd) calculated from sinus beats has been shown to identify patients prone to sustained VT. However, predictive accuracy of this parameter is limited. Electrophysiological properties of the myocardium may be altered by a premature ventricular beats, which is a well-established trigger for sustained VT. Therefore, the author hypothesised that QTd in spontaneous or paced ventricular beats may improve identification of patients with inducible sustained VT. In 28 consecutive patients (men, mean age 61 +/- 13 years) who underwent programmed ventricular stimulation, the values of QTd calculated in sinus and ventricular beats were compared between inducible and noninducible patients. The mean QTd values obtained using three different methods differed significantly, QTd in paced ventricular beats being the highest, QTd in spontaneous ventricular beats was intermediate, and QTd in sinus beats was the lowest (83.9 +/- 30 vs 63.0 +/- 29 ms vs 53.9 +/- 27 ms, P < 0.0001 and P < 0.004, respectively). In 13 (46%) patients sustained VT was induced. QTd values were significantly higher in inducible than noninducible patients (QTd sinus beats: 67.5 +/- 31 vs 42.1 +/- 11 ms, P = 0.02; QTd spontaneous ventricular beats: 79.3 +/- 35 vs 46.7 +/- 13 ms, P = 0.008, and QTd-paced ventricular beats: 104.8 +/- 32 vs 65.9 +/- 9 ms, P = 0.0009). The receiver operator characteristic curves showed that at a sensitivity level of 100%, the highest specificity for identification of inducible patients had QTd measured in paced ventricular beats (87%) followed by QTd in spontaneous ventricular beats (45%), and QTd in sinus beats (40%). In conclusion, (1) QTd in ventricular beats is greater than in sinus beats, and (2) QTd calculated from paced ventricular beats identifies patients with inducible sustained VT better than QTd measured during sinus rhythm.