冠状动脉旁路移植术对冠心病QT间期离散度的影响

为探讨冠状动脉旁路移植术 (CABG)与心室复极离散度 (QTd)的关系 ,对冠心病冠状动脉旁路移植术患者 32例术前、术后和未行冠状动脉旁路移植术患者 32例的心室复极各参数进行分析发现 :1 CABG组术前术后QTd、QTcd、QTLcd组内比较 ,术后QT间期离散度减少 ,有明显的统计学差异 (P <0 0 1)。2 CABG术后QTd、QTcd、QTLcd与未行CABG术QTd、QTcd、QTLcd组间比较、术后QT间期离散度减少 ,有明显的统计学差异 (P <0 0 1)。 3 非手术治疗组前后的QTd、QTcd、QTLcd比较 ,无明显差异 (P >0 0 5) ,结果表明 :冠状动脉旁路移植术能改善心室复极离散     

2型糖尿病合并冠心病患者QT离散度的临床研究

目的探讨2型糖尿病合并冠心病患者心电图QT离散度（QTd）及校正QT离散度（QTcd）的变化特点及临床意义。方法通过观察120例2型糖尿病合并冠心病患者心电图QTd及QTcd变化,并与112例非糖尿病冠心病患者及105例健康者对照比较。结果T2DM合并冠心病患者与非糖尿病冠心病相比,QTd及QTcd明显延长,差异有统计学意义（P〈0．01）。冠心病患者与健康者相比,QTd及QTcd明显延长,差异有统计学意义（P〈0．01）。QTd及QTcd大小顺序为：T2DM合并冠心病组〉非糖尿病冠心病组〉健康对照组。结论2型糖尿病合并冠心病患者的心肌复极不均一性增强,动态观察QTd和QTcd可作为提示糖尿病心脏病变的有效指标。     

倍他乐克对心绞痛患者QT间期离散度的影响

目的研究倍他乐克对冠心病劳力型心绞痛患者QT间期离散度(QTd)的影响。方法按照前瞻性研究设计,对162例入选患者进行随机、单盲试验研究,入选患者在治疗前做12导联同步心电图检查,测量心率、最大和最小QT间期,计算QTd、心率校正后QT间期离散度和QT间期离散度比,在治疗4周后重复上述心电图检查;治疗组服用倍他乐克50～100 mg/d,对照组服用安慰剂治疗,比较2组前后的QTd变化,用t检验进行统计学处理。结果倍他乐克可以明显缩短劳力性心绞痛患者的QTd和心率校正后QTd(QTcd),降低QT间期离散度比。比较两组治疗4周后的QTd、QTcd和QTd ratio数值,两组差异有统计学意义,QTd、QTcd和QT间期离散度比分别为(44.5±17.3)ms比(63.8±15.6)ms,P<0.01,(45.7±15.3)ms比(64.9±16.3)ms,P<0.01和4.94%±2.1%比8.08%±1.5%,P<0.001。结论倍他乐克在改善心肌缺血的同时可以明显的缩短QTd,降低QT间期离散度比;QT间期离散度比对预测冠心病患者发生恶性心律失常和猝死比QTd具有更重要的预后价值。     

冠状动脉病变严重程度、病变位置及介入治疗对QT离散度的影响

总结 15 9例冠状动脉 (简称冠脉 )造影且心电图及临床资料完整的病例 ,为探讨冠脉病变严重程度、病变位置及冠心病介入治疗对QT离散度 (QTd)及校正QT离散度 (QTcd)的影响。结果 :冠脉狭窄≥ 70 %对QTd及QTcd影响明显 (P <0 .0 5 )而冠脉狭窄 <70 %对QTd及QTcd无明显影响 ;冠脉病变所处位置对QTd及QTcd无明显影响 ;介入治疗后QTd及QTcd明显变小 ,P <0 .0 5。结论 :冠脉病变所处位置对QTd及QTcd无明显影响 ,病变严重程度及介入治疗对QTd及QTcd有明显影响。     

年轻人单纯性周围型肥胖与心电图QT离散度的关系

目的 探讨年轻人单纯性周围型肥胖与心电图QT离散度（QTd、QTcd）的关系。方法测量年轻人单纯性周围型肥胖者（A组）和体重正常者（B组）12导联同步心电图QT间期,并通过计算机数字转换得出QTd、QTcd。结果 年轻人单纯性周围型肥胖组QTd、QTcd收缩压显著高于对照组（P〈0.05）。结论 年轻人单纯性周围型肥胖的QT离散度（QTd、QTcd）显著增大,可能与肥胖致心室肌肥厚及心肌脂肪浸润等引起除极和复极不均一性有关。     

冠心病介入治疗对QT离散度的影响

目的探讨冠心病介入治疗对QT离散度的影响。方法选择127例行冠状动脉造影且心电图资料完整的患者,据造影结果分为对照组42例,治疗组85例,分别测定QT离散度(QTd)及校正QT离散度(QTcd)并进行比较。结果(1)介入治疗前治疗组与对照组相比QTd及QTcd均明显延长,统计学上差异有显著性意义(P<0.05)。(2)介入治疗后QTd及QTcd明显缩短,与介入治疗前相比,统计学上差异有显著性意义(P<0.05)。(3)介入治疗后QTd及QTcd与对照组比较,差异无显著性意义(P>0.05)。结论成功的介入治疗可缩短QT离散度,改善心肌的复极离散程度,减少心脏危险事件的发生。     

运动诱发心肌缺血时QT离散度的变化

观察运动诱发心肌缺血时QT离散度（QTd）的变化，分析68例运动负荷试验心电图。正常人运动后即刻QTd、心率校正QT离散度（QTcd）较静息时减小，QT离散率（QTr）无变化。运动诱发心肌缺血的患者，其运动后即刻QTd较静息时无差异；QTcd、QTr明显增加。表明运动诱发心肌缺血时心室肌复极时限差异增大，QTr是QT离散程度更为客观的指标。     

低血糖昏迷患者治疗前后心电图QT离散度分析

目的探讨低血糖昏迷的2型糖尿病患者治疗前后心电图QT离散度(QTd)及经过校正后QT离散度(QTcd)的变化。方法对32例急诊确诊为2型糖尿病患者并发低血糖昏迷时的心电图QTd、QTcd与经过升高血糖治疗6 h后进行对比分析。结果 2型糖尿病患者发生低血糖昏迷时的QTd、QTcd明显高于治疗后,差异均有统计学意义(P0.01)。结论低血糖昏迷导致心电图QTd、QTcd增加,与低血糖所致心脏自主神经过度激活、能量物质缺乏导致心肌细胞钠钾泵、钙泵活性下降有关。     

经皮冠状动脉腔内成形术及支架植入术对QT离散度的影响

目的　观察冠心病患者在经皮冠状动脉腔内成形术 (PTCA)及支架植入术后QT离散度(QTd)的变化。方法　 44例冠心病患者经PTCA及支架植入术后血管再通者纳入研究。术前一周内及术后 48h内分别记录体表 12导联同步心电图 ,测量QTd及QTc离散度 (QTcd)。为评价冠状动脉造影对QTd及QTcd可能产生的影响 ,我们还测量了同期 10 8例行冠状动脉造影术的患者手术前后的QTd及QTcd。结果　 (1) 10 8例行冠状动脉造影术者及其亚组 (术前QTd延长组、正常组 ,QTcd延长组、正常组 ,单支病变组 ,二支病变组 )手术前后QTd及QTcd差异均无显著性 ;(2 )PTCA及支架植入术组手术前后QTd差异也无显著性 ,但QTcd却从术前的 (5 8 9± 33 3)ms缩短至术后的 (4 7 6± 2 0 9)ms(P <0 0 5 )。亚组分析表明 :术前QTd延长组 (75 4± 2 5 2 )ms术后明显缩短 (4 7 5± 19 6 )ms,P <0 0 1;术前QTcd延长组 (95 3± 30 3)ms术后也明显改善 (5 2 5± 2 5 6 )ms ,P <0 0 1;单支病变组手术后QTd(4 1 6± 16 9)ms及QTcd(4 4 3± 18 2 )ms均较术前 [QTd及QTcd分别为 (5 5 5± 2 6 4)ms及 (6 0 3± 31 1)ms]明显缩短 (P均 <0 0 5 ) ;而术前QTc或QTcd正常组、二支病变组手术后QTc及QTcd均无明显变化。结论　PTCA及支架术可明显缩短QTcd ;     

冠心病合并2型糖尿病QT间期离散度变化的临床意义

目的探讨冠状动脉粥样硬化性心脏病(冠心病,CHD)合并2型糖尿病(DM)患者心电图QT间期离散度(QTd)变化的临床意义。方法冠心病患者252例,其中冠心病合并2型糖尿病组(CHD+DM组)150例和未合并糖尿病的冠心病组(CHD组)102例,127例健康体检者作为对照组;分析心电图QT间期离散度(QTd)及校正的QT间期离散度(QTcd)变化。结果 CHD+DM组的QTd值及QTcd值较健康对照组及CHD组明显延长(P0.01);CHD+DM组中同时合并肾病、眼病等微血管并发症者QTcd及QTd值较健康对照组和CHD组明显延长(P0.01);QTcd与血糖(r=0.290,P0.01)及血脂(r=0.167,P0.05)明显正相关。结论冠心病合并糖尿病者加重心室肌复极化的改变。     

急性心肌梗死恢复期介入治疗对QT离散度的影响

目的探讨急性心肌梗死(AMI)恢复期(2～4周)介入治疗对QT离散度(QTd)的影响。方法选定76例AMI恢复期患者,对照分析行经皮冠状动脉腔内成形术(PTCA)及冠状动脉内支架置入术术前1d和术后1h的标准12导联同步心电图,测量QTd及校正的QT离散度(QTcd),并与53例同期行冠状动脉造影结果正常者(对照组)进行比较。结果AMI组介入治疗术前最大QT间期(QTmax)、最大校正QT间期(QTcmax)、QTd及QTcd均较对照组明显增大,差异具有统计学意义(P<0.01);介入手术后QTmax、QTcmax、QTd及QTcd比术前明显降低,差异具有统计学意义(P<0.01)。而单独进行冠脉造影对QT离散度无明显影响。结论AMI患者QTd和QTcd明显高于正常人,而AMI恢复期介入治疗可使QTd和QTcd显著降低,从而降低急性心肌梗死后恶性心律失常和心源性猝死的发生率,改善AMI患者的预后。     

Clinical determinants of increased QT dispersion in patients with diabetes mellitus.

AIMS: To compare QT dispersion measurements in diabetic patients to control subjects and assess any associations between QT dispersion and diabetic clinical characteristics. METHODS: A total of 512 diabetics and 50 age and gender matched controls were studied. QT interval was measured manually in 12-lead conventional electrocardiograms, and QT dispersion (QTd), heart rate-corrected QT dispersion (QTcd), number of leads-adjusted QT dispersion (adjuQTd) and adjacent QT dispersion (adjaQTd) were calculated. Demographic, clinical, laboratory and electrocardiographic data were recorded. RESULTS: Diabetics showed increased QT dispersion compared to controls (QTd: P<0.001, QTcd: P<0.001, adjuQTd: P<0.001), even those with recent diagnosis (less than 2 years) and without arterial hypertension, ECG abnormalities or chronic degenerative complications (QTd: P=0.01, QTcd: P<0.001, adjuQTd: P=0.04). Left ventricular hypertrophy (QTd: P<0.001, QTcd: P<0.001, adjuQTd: P<0.001, adjaQTd: P<0.001) and conduction disturbances (QTd: P=0.002, QTcd: P=0.003, adjuQTd: P=0.003) were the electrocardiographic findings associated with increased QT dispersion in bivariate analysis. Clinical variables were the presence of arterial hypertension (QTd: P=0.004, QTcd: P=0.01, adjuQTd: P<0.001), even without left ventricular hypertrophy (QTd: P=0.01, QTcd: P=0.03, adjuQTd: P=0.003), and the presence of diabetic cardiovascular complications (QTd: P=0.02, QTcd: P=0.01, adjuQTd: P=0.008, adjaQTd: P=0.03). No association between QT dispersion and the presence of diabetic microvascular complications, glycaemic control, age and gender, or cardiovascular drugs was observed. Multivariate regressive statistical analysis confirmed the associations noted in bivariate analysis. CONCLUSIONS: Diabetic patients have increased QT dispersion compared to non-diabetics even those without arterial hypertension and cardiovascular complications and with recent diagnosis. The presence of arterial hypertension, diabetic cardiovascular complications and electrocardiographic abnormalities of left ventricular hypertrophy and conduction disturbances were associated to increased QT dispersion in diabetes mellitus.     

Effects of isolated coronary artery ectasia on electrocardiographic parameters reflecting ventricular heterogeneity

Isolated coronary ectatic but otherwise normal epicardial coronary arteries are an infrequent angiographic finding. We sought to determine whether coronary artery ectasia (CAE) may alter QT-interval duration and dispersion. The study population consisted of 24 patients with isolated CAE and otherwise normal epicardial coronary arteries (group 1) and sex- and age-matched subjects with atypical chest pain and otherwise normal coronary flow (group 2). Both groups underwent a routine standard 12-lead surface electrocardiogram recorded at 50 mm/s during rest. QT dispersion (QTd), corrected QT (QTc), and corrected QT dispersion (QTcd) were calculated. Distribution of sex, age, body mass index, and cardiac risk factors were similar in the 2 groups. Mean heart rate was similar in the 2 groups (74 ± 10 vs 70 ± 7, P > .05). In group 1, QTd, QTcd, and QTc were significantly higher than those of group 2 (QTd, 40 ± 17 vs 29 ± 10 milliseconds [P < .05]; QTcd, 43 ± 19 vs 30 ± 10 milliseconds [P < .05]; QTc, 410 ± 21 vs 397 ± 19 milliseconds [P < .05]). In conclusion, CAE was found to be associated with prolonged QT interval and increased QTd. Microvascular dysfunction and/or ischemia may be responsible mechanisms.     

平板运动试验中IQTd诊断冠心病的价值

目的　评价用心率调整QTd指标 (IQTd)在平板运动试验中对冠心病的诊断价值。方法　 4 3例患者在冠状动脉造影前行平板运动试验 (ETT) ,测量其运动前、运动中与ST段下移最大时或最大负荷心率时 (无ST段下移者 )QTd、校正QTd(QTdr、QTcdr、QTdp、QTcdp) ,分别计算IQTd和IQTcd。ETT后 1周内行冠状动脉造影 (CAG) ,根据CAG结果分为冠心病 (CAD)组 2 3例和冠状动脉正常 (NCAD)组 2 0例。结果　运动前的QTdr和QTc dr在CAD与NCAD组间无显著差别。在冠状动脉正常组 ,运动过程QTdp和QTcdp无显著增加 ,而在冠心病组QTdp和QTcdp有显著性增加 (P <0 0 0 1)。在运动过程中 ,QTdp、QTcdp、IQTd、IQTcd在CAD与NCAD组间有明显差异。在NCAD组QTdp、QTcdp、IQTd、IQTcd95 %上限值分别为 74ms、86ms、0 .17ms/bpm和0 2ms/bpm。用其界值作为诊断标准 ,其特异性显著高于ST段压低 ,IQTd和IQTcd的敏感性和准确性显著高于ST压低 (P <0 0 5 )。结论　提示IQTd、IQTcd可作为平板运动试验中诊断冠心病敏感、准确和特异的指标     

急性心肌梗死恢复期PTCA及支架置入术对QT离散度的影响

目的　观察急性心肌梗死 (AMI)恢复期 (2～ 4周 )行经皮冠状动脉腔内成形术 (PTCA)及支架置入术对QT离散度 (QTd)的影响。方法　选择 5 7例AMI恢复期的患者 ,分别记录PTCA及支架置入术前 1d ,术后 1h的 12导联同步心电图 ,测量QTd及校正的QTd(QTcd) ,并与 86例同期行冠状动脉造影结果正常者进行对照。结果　AMI组行PTCA及支架置入术前最大QT间期 (QTmax) ,最小QT间期 (QTmin) ,QTd及QTcd均较对照组明显增大 ,差异有显著性。前壁与下壁AMI之间上述指标差异无显著性。成功的PTCA及支架置入术后QTmax,QTmin,QTd及QTcd比术前明显缩短 ,两者相比差异有显著性。而单纯行冠状动脉造影对QT离散度无明显影响。结论　AMI患者QTd及QTcd显著高于正常人 ,而AMI恢复期成功的PTCA及支架置入术可使增加的QTd及QTcd显著缩短 ,从而减低AMI后恶性心律失常和心源性猝死的发生率 ,改善患者的远期预后。     

Effect of slow coronary flow on electrocardiographic parameters reflecting ventricular heterogeneity

QT interval dispersion reflects regional variations in ventricular repolarization and cardiac electrical instability. Previous studies have showed that QT interval dispersion changes during episodes of myocardial ischemia. Slow coronary flow (SCF) in epicardial coronary arteries is a rare and unique angiographic finding. Whether this pattern of flow is associated with electrocardiographic abnormalities is unknown. Therefore, this study was designed to investigate whether SCF results in electrocardiographic (ECG) changes compared to normal coronary flow. For this aim 24 patients with angiographically proven SCF who had no obstructive coronary lesion (group I) and 25 patients without coronary artery disease (group II) were included in the study. Both groups underwent a routine standard 12-lead surface electrocardiogram recorded at 50 mm/s during rest. QT dispersion (QTd), corrected QT (QTc), and corrected QT dispersion (QTcd) were calculated. Distributions of sex, age, body mass index (BMI), and cardiac risk factors were similar in the 2 groups. Mean heart rate was similar in the 2 groups (74 +/-8 vs 77 +/- 7 p > 0.05). Mean QRS interval durations were similar in the groups (92 +/-7 vs 90 +/-6 ms p > 0.005). In group I, QTd, QTcd, and QTc, were significantly higher than in group II (QTd: 73 +/-14 vs 40 +/-14; QTcd: 71 +/-15 vs 42 +/-9; QTc: 414 +/-14 vs 388 +/-13, respectively p <0.05). In conclusion, SCF was found to be associated with prolonged QT interval and increased QT dispersion. Ischemia in microvascular level and/or altered autonomic regulation of the heart may be responsible mechanisms.     

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.     

平板运动试验不同时段QT离散度变化的意义

目的探讨平板运动试验(TET)不同时段的QT离散度(QTd)和校正QT离散度(QTcd)变化的意义。方法选择38例TET阳性者不同时段记录的心电图用于测量、分析QTd、QTcd的变化,并与40例TET阴性者作对比分析。结果阳性组运动峰值心率时,运动中或后ST段下移最大时及运动后2、4、6分钟时的QTd、QTcd较运动前显著增大(P<0.01或P<0.05),尤以运动所致ST段下移最大时为明显,而阴性组运动相应时段的QTd、QTcd与运动前比较无明显增大(P>0.05)。结论QTd和QTcd增大,尤其ST段下移最大时的QTd,QTcd增大可作为TET结果判定的一项新的参考指标。     

Effects of Glycoprotein IIb/IIIa Inhibition on QT Dispersion in Patients with Unstable Angina and Non-Q-Wave Myocardial Infarction

Acute coronary ischemia augments inhomogeneity in ventricular repolarization, which significantly correlates with ventricular fibrillation. The effects of glycoprotein IIb/IIIa receptor inhibition on QT interval dispersion (QTd), and the effects of QTd changes on in-hospital, 30 day, and long-term cardiac events in patients with unstable angina (UA) and non-Q-wave myocardial infarction (MI) have not been investigated previously. Eighty-three patients presenting with Braunwald class IIIB UA or non-Q-wave MI were randomized to standard therapy (aspirin and unfractionated heparin, 42 patients) or tirofiban therapy: addition to standard therapy (41 patients). QT interval dispersion (QTd) and corrected QTd (QTcd) were measured prior to therapy, and 6, 24, 48, 72, and 96 hours after the initiation of the treatment. In both groups QTd and QTcd were higher than normal limits during the admission, prior to therapy. The first QTd and QTcd were not different between two groups; the remaining values were significantly lower in tirofiban group except the first and last QTd (p values for QTd at 6, 24, 48, 72, and 96 hours are 0.057, 0.045, 0.0006, 0.04, and NS, respectively, and for QTcd, they are 0.017, 0.046, 0.0004, 0.012, and 0.01, respectively). When the first QTd and QTcd compared to the following measurements in each group, the first significant decrease occurred at 6th hour (p = 0.004 for QTd, and 0.004 for QTcd) in tirofiban group, whereas in standard therapy group it was occurred at 48th hour (p = 0.02) for QTd, and 72nd hour (p = 0.019) for QTcd. While the incidence of in-hospital acute MI, recurrent refractory angina, and total major cardiac events were significantly lower in the tirofiban group (p = 0.03, 0.04, and 0.01, respectively) that early QTd recovery observed, the 30 day and long-term incidence of major cardiac events were not different between the two groups. GP IIb/IIIa receptor inhibition in addition to heparin treatment causes a faster recovery of increased QT dispersion, and the early recovery of QTd is associated with a reduction in in-hospital major cardiac events.