心得安试验对QTd的影响分析

目的 探讨心得安对心肌复极差异的影响。方法 对76例心得安试验用药前后的心率、Q—T间期、QTd、QTc、QTcd等指标，结合反应结果进行比较、分析。结果 统计资料分全部(76例)、阳性(56例)、阴性(20例)3组进行检验，用药前、后在心率、Q—T间期、QTd、QTcd等方面均有显差异(P＜0．01)，QTc均无差异(P＞0．05)。结论 心得安可减少心肌复极差异，在改善心肌血供的同时，可能有预防心律失常及猝死的作用。     

运动试验QT离散度变化与心肌缺血或T波改变相关性的研究

目的 :探讨运动试验QT离散度 (QTd)变化与心肌缺血和T波变化的相关性及评价QTd的临床应用价值。方法 :2 4 2例经冠脉造影证实冠心病而静息心电图正常 ,平板运动试验阳性 (冠心病组 )和 16 8例静息心电图有T波低平、双向、倒置或有u波 ,平板运动试验心电图正常 ,并经冠脉造影及其他检查排除器质性心脏病 (非器质性心脏病组 )。观察两组平板运动试验QTd的变化与心肌缺血和T波变化的相关性。结果 :设QTd >5 0ms为异常 ,冠心病组运动前QTd异常率为18% ,运动后为 80 % ;非器质性心脏病组运动前QTd异常率为 84 % ,运动后为 12 %。QTd的变化与T波改变相关 ,r=0 .86 ,P <0 .0 1;与冠心病运动后单纯缺血性ST段下移无相关性。结论 :运动试验QTd变化与心肌缺血无相关性 ,QTd异常不能判断心肌复极不均一性进而预测恶性心律失常或心脏猝死 ,而只是反映T波非特异性异常的一个粗浅的量化指标     

平板运动试验前后Q—T离散度变化的临床意义

目的 为了解QT离散度(QTc)及运动耐量对乎扳运动试验(TET)结果判断的价值。方法 对50例TET进行分组观察州改变。14例TET阳性(A组)和36例阴性(B组)，B组运动耐量＜8METs的11例阴性(B1组)和＞8METs的25例阴性(B2组)进行运动前后的QTd比较。结果 运动前A组与B组比较无显差异。运动后4imn和8min A组与B组比较QTd变化存在显差异(P＜0．05)。A组运动后4min和8min QTD较运动前显延长(P分别＜0．01与0．05)，B组运动后4min和8min与运动前比较无显差异(P＞0．05)，B组中之B1组运动后4min和8min QTd较运动前也显延长(P分别＜0．01与0．05)，而B2组运动后则不延长，反而缩短。结论 TET后QTd增大，表现为低运动耐量。这是否可作为判断运动试验结果的有用指标，值得商榷。     

期前收缩后心肌复极异常的临床意义探讨

目的：探讨期前收缩后心肌复极异常的临床意义。方法：分析247例期前收缩后心肌复极的变化情况。结果：期前收缩后伴与不伴有心肌复极异常的病因，心血管病分别为68／78例与58／169例，其中冠心病分别38／78例与18／169例，差异均有非常显著性意义（P＜0．01），冠心病期前收缩后T波倒置加深、ST段改变、T波改变伴ST段和／或U波异常较其它各疾病组明显增高，差异均具有显著性意义（P＜0．05）；频发与偶发室上性期前收缩及室性期前收缩所出现的各类型心肌复极异常差异均无显著性意义（P＞0．05）。结论：期前收缩后伴心肌复极异常主要见于心血管疾病，可提示为器质性期前收缩，有助于与功能性期前收缩相鉴别，对冠心病的诊断有一定意义。     

倾斜试验配合心得安试验对心血管疾病的诊断价值

目的对功能性和器质性Ｔ波异常者倾斜前后Ｔ波改变的不同表现及对心得安试验阳性率，结合冠状动脉（冠脉）造影血管病变的严重程度加以分析。方法采用ＤＴ－１型自动倾斜床测定倾斜前后心率，血压及１２导联心电图及其服用心得安以后的变化。对器质性Ｔ波异常、功能性Ｔ波异常及对照组三组进行比较。结果（１）功能组心得安阳性率为８５％，器质组心得安阳性率为１５％（Ｐ＝０．００００）；（２）功能组心得安试验阳性倾斜前后心率均明显高于对照组（Ｐ＝０．０１６、０．００２），服用心得安２小时后平卧及倾斜后的平均心率均明显低于用药前（Ｐ＝０．０００）；（３）功能组心得安试验阳性服用心得安２小时后平卧位ＱＴｃ值明显小于服药前（Ｐ＝０．０１９），器质组心得安试验阴性服用心得安２小时后ＱＴｃ值与用药前无明显变化（Ｐ＞０．５）；（４）功能组倾斜后Ｔ波异常加重，服用心得安后明显改善，器质组倾斜后Ｔ波伪改善，心得安无效。结论功能性Ｔ波异常与β受体应答性的改变有关，而器质性Ｔ波异常则主要与缺血部位心肌β受体分布的不均一性有关     

室性心律失常患者的心率变异性分析

目的：探讨自主神经系统活动在室性心律失常（VR）发生中的作用。方法：分析38例正常人（A组）,46例无器质性心脏病VR（B组）及45例器质性心脏病VR（C组）的心率变异性（HRV）。结果：（1）与A组比较，B组SDNN，PNN50，RMSSD，HRVTI显降低（P＜0．05－0．01），SDANN，SDNNindex无显差异（P＞0．05）；C组各项指标均显降低（P＜0．01），（2）C组各项指标均比B组显降低（P＜0．05－0．01）。提示：迷走神经张力降低在VR的发生中起重要作用，HRV减低可作为高危性VR的独立预测指标。     

32例肺癌患者心肌缺血时QT离散度分析

目的：观察肺癌患出现心肌缺血时的QT离散度（QTd)的变化。方法：随机测量量32例在治疗过程中出现心肌缺血在缺血前后的QTd值,并与40例未出现心肌缺血和40例健康对对比观察,结果：心肌缺血组的心肌缺血后QTd较心肌缺血前、无心肌缺血组和健康组显增大（P＜0．01）,而心肌缺血前QTd、无心肌缺血组和健康组比较无明显增大（P＞0．05）。结论：肺癌患心肌缺血时QTd值显增加。     

氯化钾-心得安试验在鉴别功能性T波中的应用

随着对T波改变发生机制的不断探索，对器质性T波与功能性T波鉴别已提到日程上来，在正常人群中有0．5％～4．2％存在T波异常，而其中约40％，尤其在基层医院会被误诊为冠心病。在众多鉴别方法中，氯化钾试验、心得安试验广泛应用于中小医院，本文通过两者组合成氯化钾-心得安试验，旨在探讨试验鉴别T波作用的机制，选择最佳试验方法及时间。     

胺碘酮对阵发性心房纤颤病人P波离散度的影响

目的：探讨胺碘酮对阵发性心房纤颤病人P波离散度的影响,以评价P波离散度判断药物疗效的意义。方法：有阵发性心房纤颤病史的23名患进入观察组,另选23名无心房纤颤及其它器质性心脏病为对照线,测量其P波离散度（PD）,观察组在服用胺碘酮15到20天后复查P波最大间期（Pmax)和PD。观察治疗前后和组间PD和Pmax的变化和差异,结果：与对照组相比,观察组Pmax与PD显增加,P分别＜0．05,0．01,观察组服胺碘酮后Pmax与PD明显下降,P分别＜0．05,0．01,但治疗后PD仍明显高于对照组（P＜0．01）,结论：PD对预测心房纤颤有较好的敏感性及特异性,对于胺碘酮抗房颤作用的疗效评价有一定的作用。     

立位心电图ST-T变化对器质性心脏病伴β-受体过敏综合征的诊断意义

目的　探讨立位心电图 ST- T变化在器质性心脏病伴 β-受体过敏综合征诊断中的意义。方法　对 35例健康者 (组 ) ,4 2例 β-受体过敏综合征 (组 ) ,34例器质性心脏病 (组 ) ,36例器质性心脏病伴 β-受体过敏综合征 (组 )患者的卧、立位心电图 ST- T波及心率进行对比研究 ,并观察心得安试验对其影响。结果　组 与组 ,组 与组 卧、立位心率增快程度不同 ,后者均分别大于前者 (P<0 .0 1) ;组 患者的卧位心电图 ST- T正常 ,转为立位时ST- T发生异常改变 (71.4 2 % ) ,或卧位心电图 ST- T异常 ,转为立位时 ST- T异常的程度与范围加重 (2 8.5 7% ) ;组 心电图 ST- T正常及组 原有 ST- T改变者分别在卧、立位对比时无明显变化 ;组 者立位时原异常 ST- T变化的程度与范围加重 (10 0 % ) ;卧位心得安试验使组 患者的心电图 ST- T改变完全恢复正常 ,组 无改善 ,组 轻度改善。结论　立位心电图 ST- T动态变化、心率增快程度及心得安试验 ,对器质性心脏病伴 β-受体过敏综合征的诊断、治疗指导具有重要意义     

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.     

Enhanced detection of ischemic but viable myocardium by QT interval dispersion on treadmill exercise electrocardiograms of patients with healed anterior wall myocardial infarcts

BACKGROUND: The presence of ischemic but viable myocardium in infarcted areas is an important indication for coronary revascularization, but is often difficult to detect with the use of treadmill exercise electrocardiography (ECG). HYPOTHESIS: QT interval dispersion (QTd) is a sensitive method for detecting myocardial ischemia and may improve the accuracy of treadmill exercise ECG testing for detecting ischemic but viable myocardium in infarcted areas. METHODS: Forty-five patients with Q-wave anterior wall myocardial infarctions who underwent treadmill exercise ECG, exercise reinjection thallium-201 (201Tl) scintigraphy, radionuclide angiocardiography, and coronary angiography 1 month after infarction were enrolled in this study. The presence of viable myocardium in the infarct area was determined by exercise reinjection 201Tl scintigraphy. Patients who had no redistribution in the infarct area after reinjection were included in Group 1, and those with redistribution were included in Group 2. RESULTS: QTd immediately after exercise, and the difference between QTd before and immediately after exercise, were significantly greater in Group 2 than in Group 1. The sensitivity, specificity, and accuracy of conventional ST-segment depression criteria for detecting viable myocardium in the infarct area were 48, 64, and 56%, respectively. The measurement of QTd immediately after exercise (abnormal: > or = 70 ms; normal: < 70 ms) improved the sensitivity, specificity, and accuracy to 78, 82, and 80%, respectively. CONCLUSIONS: This novel diagnostic method using QTd-based criteria significantly improves the clinical usefulness of treadmill exercise ECG testing for detecting ischemic but viable myocardium in infarct areas in patients with healed Q-wave anterior wall myocardial infarctions.     

用体表心电标测方法探讨复极离散及空间分布

目的　用体表心电标测时空图法探讨复极离散空间分布和临床价值。方法　采用体表心电标测时空图法及12导联心电图 ,分别测定 6 8例急性心肌梗死 (AMI)患者的QT间期及QT离散度 (QTd) ,并与 5 8例正常对照者进行对比。结果　 (1)在正常人及AMI患者时空图法测得QTd均大于 12导联心电图 ,两种方法均表明AMI后QTd增加。 (2 )正常人时空图分布 :T波呈单群、结束时间相对较一致 ;AMI后时空图分布发生明显变化 :梗死区对应体表部位T波结束延长 ,大致分 3型 ,部分患者可见零线垂直偏斜 ,ST T复极过程中分群现象 ,T波结束离散增大。 (3)AMI患者死亡及合并室性心律失常者时空图法测得QTd较无心律失常者增加、分布主要表现第Ⅰ、Ⅲ型 (18/ 2 1) ,12导联心电图未发现两组间差异。 (4 )时空图尚可展示相邻部位的复极离散和U波分布。结论　时空图法可直观反映QT间期空间分布及离散 ,并能有效鉴别U波 ,可能会成为QTd研究中一项有前途的方法     

Value of QT dispersion in diagnosis of restenosis after intracoronary stent implantation

We studied the ECGs of patients with single vessel disease before and after (long term) coronary stent implantation. The interlead variability of the QT interval, known as QT dispersion (QTd), is believed to reflect the regional variations in ventricular repolarization and, thus, may provide an indirect marker of arrhythmogenicity. There are no reliable noninvasive markers of significant restenosis after stent implantation. The effect of coronary revascularization on QTd in patients who underwent coronary stenting has not been investigated extensively. The aim of this study was to evaluate the value of QTd in predicting restenosis after intracoronary stent implantation. QTd with 12 lead surface ECG was measured in 48 patients (21 with restenosis and 27 without restenosis; 33 male; mean age, 58+/-10.8 years) before the procedure and after long-term follow-up (mean, 6.8+/-3.2 months). All patients had coronary angiographic control at the end of the follow-up period. QTd (as the difference between the maximum and minimum QT interval measured from 12 lead ECG) and rate-corrected QT (QTcd) were evaluated at rest. In 27 patients without restenosis, QTd and QTcd decreased from 58+/-14.4 and 62.8+/-20.4 ms to 26.3+/-9.2 and 29.6+/-10.6 ms in the long term follow-up, respectively (P<0.001). However, in 21 patients with restenosis, there was no significant change in QTd and QTcd intervals and they were still increased at the end of the long-term follow-up (P>0.05). In conclusion, increased QT interval dispersion may be an inexpensive and simple marker of restenosis after intracoronary stent implantation.     

The acute effect of trastuzumab infusion on ECG parameters in metastatic breast cancer patients

OBJECTIVES: Although trastuzumab therapy is known to be associated with congestive heart failure, its arrhythmogenic potential has not been studied in detail. The purpose of this study was to determine the acute influence of trastuzumab infusion on electrocardiogram (ECG) parameters in patients with metastatic breast cancer. PATIENTS AND METHODS: Twenty patients with HER2 overexpressing metastatic breast cancer and normal cardiac function were enrolled in this single-centre prospective study. Standard 12-lead ECG recordings were performed at baseline and after trastuzumab infusion (2 mg/kg given over 30 min). P-wave durations, QT and RR intervals were measured and QT dispersion (QTd) and P-wave dispersion (Pd) were calculated. RESULTS: In comparison with baseline, no statistically significant change in any ECG parameters, including QT and RR intervals, P wave durations, Pd and QTd, was observed after infusion of trastuzumab. CONCLUSION: In this study, no abnormality of atrial and ventricular depolarisation and repolarisation, indicated by Pd and QTd, was detected after infusion of trastuzumab. As Pd and QTd are both known to be associated with increased risk of serious arrhythmias and sudden death, it would appear that trastuzumab has no acute arrhythmogenic potential related to cardiac depolarisation and repolarisation.     

Changes in the QT interval and its adaptation to rate, assessed with continuous electrocardiographic recordings in patients with ventricular fibrillation, as compared to normal individuals without arrhythmias

Various QT interval variables and heart rate variability parameterswere studied in six patients with ventricular fibrillation butwithout heart disease and compared with findings in 21 normalpersons. QT and QT dispersion (QTd) were measured from conventional12 lead ECGs; for dynamic QT analysis, QT intervals were automaticallymeasured to the end of the T wave (QTe) on a 24 h ECG recording.The adaptation of the QT interval to changes in heart rate wasexpressed as the slope of the linear regression lines relatingQTe to the RR interval (Se). The complete 24 h ECG recordingand four 6 h segments were studied (morning, day, evening, andnight). Ventricular fibrillation patients had slightly prolongedQT_max intervals on the 12 lead ECG, QT dispersion was longerin ventricular fibrillation patients than in normal persons(88±29 ms vs 59±26 ms, p<0·05), andon the 24 h ECG recording, normal persons and ventricular fibrillationpatients had a comparable RR. In addition, parameters for long-term (SD, standard deviationof normal RR intervals) and short-term (RMSSD, the root-mean-squaresuccessive differences of normal RR intervals) heart rate variabilitywere not different. Automatic measurement of the QT intervaland the QTe/RR slopes was possible over 24 h and in the 6 hintervals in a large majority of patients (25/27 and 88/108readings). The mean 24 h QT and the mean 6 h QT interval werecomparable in normal subjects and ventricular fibrillation patientsexcept for the day segment. The 24 h Se was significantly lowerin ventricular fibrillation patients, compared to normal individuals.Furthermore, Se in the morning and night segment was also significantlylower in ventricular fibrillation patients (both p<0·05). In conclusion, patients with ventricular fibrillation but withoutunderlying structural heart disease have normal heart rate variabilityparameters. However, abnormal re-polarization behaviour, characterizedby an increased QTd and a depressed adaptation of QT to variationsin RR (especially during the night and the morning), is present.These findings may help to understand and treat arrhythmiasin this patient group.     

冠心病冠状动脉介入治疗前后QT离散度的比较

目的　探讨成功的冠状动脉介入手术 (PTCA及冠状动脉内支架置入术 )对冠心病患者QT离散度 (QTd)的影响。方法　考察 2 5 2例冠心病患者成功进行介入手术前后十二导联同步心电图的结果 ,计算QTd和校正的QT离散度 (QTcd)并进行对比分析。结果　 2 5 2例冠心病患者经PTCA或加支架植入术共处理的病变有 383处 ,除 2 8例外 ,术后QTd缩短明显 ;介入手术前后QTd及QTcd比较有显著性差异 (P <0 0 5 ) ;血流灌注术后均达到TIMIⅢ级与Ⅱ级 ,两组术前QTcd比较以及术后下降幅度无显著差异 (P >0 0 5 ) ;单支与多支病变术前QTcd无显著差异 (P >0 0 5 ) ,术后下降幅度则有显著差异 (P <0 0 5 )。结论　冠心病经成功的介入治疗后QT离散度明显减小 ,QT离散度可作为介入手术后心肌再灌注成功的一个参考指标。     

QT dispersion does not represent electrocardiographic interlead heterogeneity of ventricular repolarization

INTRODUCTION: QT dispersion (QTd, range of QT intervals in 12 ECG leads) is thought to reflect spatial heterogeneity of ventricular refractoriness. However, QTd may be largely due to projections of the repolarization dipole rather than "nondipolar" signals. METHODS AND RESULTS: Seventy-eight normal subjects (47+/-16 years, 23 women), 68 hypertrophic cardiomyopathy patients (HCM; 38+/-15 years, 21 women), 72 dilated cardiomyopathy patients (DCM; 48+/-15 years, 29 women), and 81 survivors of acute myocardial infarction (AMI; 63+/-12 years, 20 women) had digital 12-lead resting supine ECGs recorded (10 ECGs recorded in each subject and results averaged). In each ECG lead, QT interval was measured under operator review by QT Guard (GE Marquette) to obtain QTd. QTd was expressed as the range, standard deviation, and highest-to-lowest quartile difference of QT interval in all measurable leads. Singular value decomposition transferred ECGs into a minimum dimensional time orthogonal space. The first three components represented the ECG dipole; other components represented nondipolar signals. The power of the T wave nondipolar within the total components was computed to measure spatial repolarization heterogeneity (relative T wave residuum, TWR). QTd was 33.6+/-18.3, 47.0+/-19.3, 34.8+/-21.2, and 57.5+/-25.3 msec in normals, HCM, DCM, and AMI, respectively (normals vs DCM: NS, other P < 0.009). TWR was 0.029%+/-0.031%, 0.067%+/-0.067%, 0.112%+/-0.154%, and 0.186%+/-0.308% in normals, HCM, DCM, and AMI (HCM vs DCM: NS, other P < 0.006). The correlations between QTd and TWR were r = -0.0446, 0.2805, -0.1531, and 0.0771 (P = 0.03 for HCM, other NS) in normals, HCM, DCM, and AMI, respectively. CONCLUSION: Spatial heterogeneity of ventricular repolarization exists and is measurable in 12-lead resting ECGs. It differs between different clinical groups, but the so-called QT dispersion is unrelated to it.     

Changes in QT dispersion during adenosine infusion

BACKGROUND: QT dispersion (QTd) measurement during treadmill stress testing has been to shown to improve the accuracy of exercise electrocardiogram (ECG) in the detection of significant coronary artery disease (CAD). HYPOTHESIS: The aim of this study was to determine whether adenosine-induced changes in QTd could predict significant CAD and to assess its efficacy as a diagnostic index in patients undergoing adenosine stress test. METHODS: QT interval measurements were made in 57 consecutive patients undergoing adenosine sestamibi stress test. Patients with an abnormal stress test underwent coronary angiography. Patients with significant disease by coronary angiography (> 70% stenosis) were classified as having CAD (Group 1), and those with normal stress images and/or normal coronaries by angiography were classified as having no CAD (Group 2). RESULTS: QT dispersion increased from 28.2 +/- 4.5 to 43.8 +/- 4.5 ms with a delta QTd of 15.53 +/- 3.68 in Group 1 (p = 0.001) and from 28.4 +/- 2.6 to 34.8 +/- 2.8 ms with a delta QTd of 6.58 +/- 2.21 ms in Group 2 (p = 0.006). Patients in Group 1 had a significantly higher increase in QTd (delta QTd) than the patients in Group 2 (p < 0.03). Addition of delta QTd (> 10 ms) to the ST depression during adenosine infusion would increase the sensitivity of the ECG from 23 to 65% and decrease the specificity from 91 to 70% for diagnosis of significant CAD. CONCLUSIONS: delta QTd is significantly more prolonged in patients with CAD during adenosine infusion. It increases the sensitivity of the stress ECG in diagnosis of CAD during adenosine infusion when used as an adjuvant index.