平板运动试验心电图阳性各时段QTd和QTcd观察

目的观察平板运动心脏负荷试验诱发患者心电图ST段缺血型改变时QT离散度（QTd）和校正QT离散度（QTcd）。方法选择临床疑诊为冠心患者进行平板运动负荷心电图试验,诱发心电图ST段呈缺血型下移者35例（缺血组）,测量运动前、运动后缺血型ST段下移达最大值时及运动后ST段恢复正常时QTd及QTcd,与平板运动负荷心电图ST段无缺血型改变者35例（正常组）进行对比研究。结果缺血组在运动后ST段下移达最大值时QTd、QTcd分别为（57．60±11．74）及（76．62±9．35）ms,与运动前及运动后ST段恢复正常时的QTd、QTcd之间存在显著差异（P〈0．01）,与正常组运动后即刻QTd、QTcd对比同样存在显著差异（P〈0．01）,而正常组在运动前、运动后即刻及运动后6min时QTd、QTcd无显著性差异（P〉0．05）。结论平板运动负荷试验诱发冠心病患者心电图ST段呈缺血型改变时QTd、QTcd明显增大。冠心病患者心肌缺血时存在心肌复极的不均一性和电的不稳定性,是导致严重室性心律失常和心脏猝死的独立危险因素。     

流行性出血热并发窦性心动过缓的护理

流行性出血热(epidemic hemorrhagic fever,EHF)又名肾综合征出血热(hemorrhagic fever with renalsyndaxne,HFRS),是以肾脏损害为主的一种自然疫源性疾病,病情复杂多变,并发症多,窦性心动过缓是其中之一,位居出血热心脏改变的首位,占心律失常的57.05％。如果窦性心动过缓出现阿斯氏综合征,直接威胁病人的生命。因此,预防和减少流行性出血热并发窦性心动过缓的发生是感染科护理工作者十分关注的问题。本院感染科自1994年1月至2001年12月收治:EHF并发窦性心动过缓235例,护理体会报道如下。     

左颈部包块致窦性心动过缓1例

患者，男，56岁，入院诊断为“左颈部包块半年，窦性心动过缓。”术前针吸病理诊断为“良性梭形细胞源性实性肿瘤”。心电图示“心率54次／min，窦性心动过缓”。由于阿托品激发试验阴性，拟于2005年3月3日在全麻下行左颈部包块切除术。术前半小时肌注阿托品0．75mg，鲁米那0．1g。入室后先行颈丛阻滞，由于效佳，未行气管插管全麻。监测心电、无创血压，同时面罩给氧，SpO2维持在99％。     

简易下蹲运动试验鉴别飞行人员窦性心动过缓的价值分析

目的 探讨简易下蹲运动试验鉴别飞行人员窦性心动过缓的价值.为其健康鏊定提供参考依据.方法 对75例常规心电图检查心室率<55次/min的飞行人员进行下蹲运动试验(2 min内下蹲60次),比较运动前后心室率变化情况.结果 受检者均在规定时间内完成下蹲运动试验.运动前心室率40～53次/min,平均为(48.5±4.5)次/min,下蹲运动后即刻心室率均>90次/min,平均为(103.5±9.0)次/min,无自觉症状和不良反应出现.结论 下蹲运动试验结果 可靠,可作为鉴别飞行人员窦性心动过缓性质的一种简便方法.     

平板运动试验心电图阳性各时段QTd和QTcd观察

目的 观察平板运动心脏负荷试验诱发患者心电图ST段缺血型改变时QT离散度(QTd)和校正QT离散度(QTcd).方法 选掸临床疑诊为冠心患者进行平板运动负荷心电图试验,诱发心电图ST段呈缺血型下移者35例(缺血组),测量运动前、运动后缺血型ST段下移达最大值时及运动后ST段恢复正常时QTd及QTcd,与平板运动负荷心电图ST段无缺血型改变者35例(正常组)进行对比研究.结果 缺血组在运动后ST段下移达最大值时QTd、QTcd分别为(57.60±11.74)及(76.62±9.35)ms,与运动前及运动后ST段恢复正常时的QTd、QTcd之间存在显著差异(P<0.01),与正常组运动后即刻QTd、QTcd对比同样存在显著差异(P<0.01),而正常组在运动前、运动后即刻及运动后6 min时QTd、QTcd无显著性差异(P>0.05).结论平板运动负荷试验诱发冠心病患者心电图ST段呈缺血型改变时QTd、QTcd明显增大.冠心病患者心肌缺血时存在心肌复极的不均一性和电的不稳定性,是导致严重室性心律失常和心脏猝死的独立危险因素.     

平板运动试验心电图阳性各时段QTd和QTcd观察

目的 观察平板运动心脏负荷试验诱发患者心电图ST段缺血型改变时QT离散度(QTd)和校正QT离散度(QTcd).方法 选掸临床疑诊为冠心患者进行平板运动负荷心电图试验,诱发心电图ST段呈缺血型下移者35例(缺血组),测量运动前、运动后缺血型ST段下移达最大值时及运动后ST段恢复正常时QTd及QTcd,与平板运动负荷心电图ST段无缺血型改变者35例(正常组)进行对比研究.结果 缺血组在运动后ST段下移达最大值时QTd、QTcd分别为(57.60±11.74)及(76.62±9.35)ms,与运动前及运动后ST段恢复正常时的QTd、QTcd之间存在显著差异(P<0.01),与正常组运动后即刻QTd、QTcd对比同样存在显著差异(P<0.01),而正常组在运动前、运动后即刻及运动后6 min时QTd、QTcd无显著性差异(P>0.05).结论平板运动负荷试验诱发冠心病患者心电图ST段呈缺血型改变时QTd、QTcd明显增大.冠心病患者心肌缺血时存在心肌复极的不均一性和电的不稳定性,是导致严重室性心律失常和心脏猝死的独立危险因素.     

心肌梗死患者QTd、QTcd及QTdr的诊断性试验评价

有研究认为 ,急性与陈旧性心肌梗死时 QT间期离期度 (包括 QTd、QTcd和 QTdr)明显延长 ,QTdr在评价心室肌复极差异性方面较前两者优越。本研究就心肌梗死患者以上 3个指标间是否存在差异进行诊断性试验评价。1　资料与方法1.1　研究分组 :心血管病专科门诊或住院诊断的心肌梗死患者 2 17例 ,其中男176例 ,女 4 1例 ;年龄 2 5～ 91岁 ,平均(5 8.7± 11.3)岁 ;陈旧性心肌梗死 16 3例 ,亚急性心肌梗死 5 4例 ;全部病例均无电解质紊乱 ,未使用影响心室肌复极的抗心律失常药。对照组从来自同一仪器采样的健康人群中随机匹配 10 0例 ,其中男 6…     

体表心电图诊断窦性心动过缓、窦房阻滞的体会

正常情况下,小儿新陈代谢旺盛,交感神经占优势,年龄愈小心率愈快,窦性心动过缓（SB）很少见,其病理意义较窦性心动过速更重要。近年来观察〉3岁以上的患儿SB、窦房传导阻滞（SAB）呈增多趋势,婴幼儿出现明显SB、SAB视为病理的现象[1]。在临床上SB常合并窦性心律不齐,     

急性颈髓损伤并发窦性心动过缓的护理

总结28例急性颈髓损伤并发窦性心动过缓的护理经验,认为在护理该类患者时,护理重点是保持呼吸道通畅,防止低氧血症,避免诱发窦性心动过缓,加强生命体征及血流动力学的监测,及时改善血流动力学状态是防止心博停止的关键,药物的正确使用和副作用的观察是提高疗效的保证。     

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。     

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     

35例窦缓者食道调搏电生理测定报告

本文报告35例不明原因窦缓者的食道调搏电生理检查结果,着重对反映窦房结功能的心脏固有心率。窦房结恢复时间、校正窦房结恢复时间、窦房传导时间进行分析,并揭示了其相关性。     

56例扩张型心肌病患者QT离散度变化

目的:探讨扩张型心肌病(DCM)QT离散度(QTd)与恶性室性心律失常的关系。方法:选择32例恶性室性心律失常DCM,24例非恶性室性心律失常DCM和43例非心脏疾病患者,测定QTd,QTcd。结果:DCM恶性室性心律失常组及非恶性室性心律失常组QTd,QTcd明显高于对照组(P<0.05);DCM恶性室性心律失常组QTd,QTcd明显高于非恶性室性心律失常组。结论:QTd及QTcd可能是DCM恶性室性心律失常的监测指标。     

Determinant of QT Dispersion in Patients with Hypertrophic Cardiomyopathy

KAWASAKI, T., et al. : Determinant of QT Dispersion in Patients with Hypertrophic Cardiomyopathy. QT dispersion is thought to reflect a regional difference in repolarization process although QT interval is composed of depolarization and repolarization. This study was designed to investigate the effect of depolarization and repolarization on QT dispersion in hypertrophic cardiomyopathy. Standard 12-lead ECG was recorded in 70 hypertrophic cardiomyopathy patients with anteroseptal wall hypertrophy (HC-As), 8 patients with lateral wall hypertrophy (HC-L), 8 patients with diffuse hypertrophy (HC-D), and 46 normal controls. QRS, JTc, maximum and minimum QTc, and QTc dispersion were compared. The maximum QTc was greater in HC-As and HC-L than in the control; the minimum QTc was similar in all 3 groups; consequently, QTc dispersion was greater in HC-As and HC-L. In HC-D, the maximum QTc and the minimum QTc were greater than the control, which produced QTc dispersion similar to that in the control. JTc did not differ among 4 groups. In hypertrophic cardiomyopathy, both QTc and QRS duration were increased in the leads coinciding with the left ventricular portion of localized hypertrophy. We conclude that QTc dispersion depended on the heterogeneity of QRS duration or depolarization rather than repolarization, which in fact may be ascribed to the regionally different hypertrophy of the left ventricle in hypertrophic cardiomyopathy. (PACE 2003; 26[Pt. I]:819–826)     

Magnetocardiographic QT Interval Dispersion in Postmyocardial Infarction Patients with Sustained Ventricular Tachycardia: Validation of Automated QT Measurements

T dispersion is a measure of heterogeneity in ventricular repolarization. Increased ECG QT dispersion is associated with life-threatening ventricular arrhythmias. We studied if magnetocardiographic (MCG) measures of QT dispersion can separate postmyocardial infarction patients with and without susceptibility to sustained VT. Manual dispersion measurements were compared to a newly adapted automatic QT interval analysis method. Ten patients with a history of sustained VT (VT group) and eight patients without ventricular arrhythmias (Controls) were studied after a remote myocardial infarction. Single-channel MCGs were recorded from 42 locations over the frontal chest area and the signals were averaged. QT dispersion was defined as maximum — minimum or standard deviation of measured QT intervals. VT group showed significantly more QT and JT dispersion than Controls. QT_apex dispersions were 127 ± 26 versus 83 ± 21 ms (P = 0.004) and QT_end dispersions 130 ± 37 versus 82 ± 37 ms (P = 0.013), respectively. Automatic method gave comparable values. Their relative differences were 9% for QT_apex and 27% for QT_end dispersion on average. In conclusion, increased MCG QT interval dispersion seems to be associated with a susceptibility to VT in postmyocardial infarction patients. MCG mapping with automated QT interval analysis may provide a user independent method to detect nonhomogeneity in ventricular repolarization.     

Comparative Reproducibility of QT, QT Peak, and T Peak-T End Intervals and Dispersion in Normal Subjects, Patients with Myocardial Infarction, and Patients with Hypertrophic Cardiomyopathy

Abnormal repolarizaiion is associated with arrhythmogenesis. Because of controversies in existing methodology, new computerized methods may provide more reliable tools for the noninvasive assessment of myocardial repolarization from the surface electrocardiogram (ECC). Measurement of the interval between the peak and the end of the T wave (TpTe interval) has been suggested for the detection of repolarization abnormalities, but its clinical value has not been fully studied. The intrasubject reproducibility and reliability of automatic measurements of QT, QT peak, and TpTe interval and dispersion were assessed in 70 normal subjects, 49 patients with acute myocardial infarction (5th day; MI), and 37 patients with hypertrophic cardiomyopathy (HC). Measurements were performed automatically in a set of 10 ECCs obtained from each subject using a commercial software package (Marquette Medical Systems, Milwaukee, WI, U.S.A.). Compared to normal subjects, all intervals were significantly longer in HC patients (P < 0.001 for QT and QTp; p < 0.05 for TpTe); in MI patients, this difference was only significant for the maximum QT and QTp intervals (P < 0.05). In both patient groups, the QT and QTp dispersion was significantly greater compared to normal subjects (P < 0.05) but no consistent difference was observed in the TpTe dispersion among all three groups. In all subjects, the reproducibility of automatic measurement of QT and QTp intervals was high (coefficient of variation, CV, 1%-2%) and slightly lower for that of TpTe interval (2%–5%; p < 0.05). The reproducibility of QT, QTp, and TpTe dispersion was lower (12%–24%, 18%–28%, 16%–23% in normal subjects, MI and HC patients, respectively). The reliability of automatic measurement of QT, QTp, and TpTe intervals is high but the reproducibility of the repeated measurements of QT, QTp and TpTe dispersion is comparatively low.     

QT Duration and Dispersion in Patients with Anomalous Origins of Coronary Arteries

Background: Coronary artery anomalies have been reported to show various symptoms ranging from chest pain and dyspnea to cardio-respiratory arrest and sudden death. In this study, we attempted to assess the changes in QT interval duration and dispersion in anomalous origins of coronary arteries (AOCA).
Methods: Nineteen AOCA patients (mean age: 52 ± 11 years) and 30 healthy control subjects (mean age: 50 ± 12 years) were included in the study. Minimum and maximum corrected QT intervals, and corrected QT dispersion were calculated. The two groups were compared in terms of QT dispersion and QT duration.
Results: There was no difference between the two groups in terms of baseline demographic characteristics. Maximum corrected QT intervals (QTc max), minimum corrected QT intervals (QTc min), and corrected QT dispersion were higher in AOCA patients than controls (452 ± 38 vs 411 ± 25 ms [P = 0.0001], 402 ± 31 vs 383 ± 28 ms [P = 0.048], and 51 ± 30 vs 28 ± 12 ms [P = 0.001], respectively).
Conclusion: In the patients with anomalous origins of coronary arteries, QT dispersion that is an indicator of sudden cardiac death and arrhythmias frequency increased. QTc max, QTc min, and corrected QT dispersion are higher in patients with anomalous origin of the coronary artery than in control subjects.     

QT Interval Dispersion and its Clinical Utility

QT dispersion as a measure ofin-terlead variations of QT interval duration in the surface 12-lead ECG is believed to reflect regional differences in repolarization heterogeneity and thus, may provide an indirect marker of arrhythmogenicity. Methodology for determining QT dispersion and reproducibility of this parameter vary significantly between studies and, together with some other unresolved problems witb QT dispersion assessment, often lead to contradictory suggestions about potential clinical utility of this parameter. The results of our own study in 213 survivors of myocardial infarction, together with a comprehensive review of the literature, suggest that most of these inconsistencies reflect incomplete understanding of electrocardiographic correlates of both normal and abnormal ventricular repolarization. The application of more objective techniques, such as spectral analysis or combined assessment of different parameters (e.g., area beneath the T wave and its symmetricity) may add a new dimension to the noninvasive assessment of ventricular repolarization.     

Evaluation of Autonomic Influences on QT Dispersion Using the Head-Up Tilt Test in Healthy Subjects

Our objective was to examine the autonomic influence on QT interval dispersion using the head-up tilt test in healthy subjects. RR and QT intervals, heart rate variability, and plasma norepinephrine concentration were measured in the supine position and tilting to 70 degrees for 20 minutes using a footboard support in 15 healthy male volunteers (mean age +/- SD: 28.0 +/- 4.5 years). The rate-corrected QT interval (QTc) was calculated using Bazett's formula, and QT and QTc dispersions were defined as the maximum minus minimum values for the QT and QTc, respectively, from the 12-lead ECG. Spectral analysis of the heart rate variability generated values for the low- and high-frequency powers (LF and HF) and their ratio (LF/HF). Compared with values obtained in the supine position, tilting significantly increased QT (P < 0.05) and QTc dispersion (P < 0.01), the LF/HF ratio (P < 0.0001), and plasma norepinephrine concentration (P < 0.0001), and significantly decreased HF (P < 0.0001). QTc dispersion was positively correlated with the LF/HF ratio and plasma norepinephrine concentration, and negatively correlated with HF. These results suggest that head-up tilt testing increases QT dispersion by increasing sympathetic tone and/or decreasing vagal tone in healthy subjects.