AGING EFFECTS ON MYOCARDIAL REPOLARIZATION

最近的研究表明，除了绝对持续时间外， QT间期的离散度， 标准12导联上不同导联的QT间期差异 ECG可能与高危患者的不良预后相关 心律紊乱的症状 尽管一些人口研究 研究了QT离散度，老化对这一潜在的影响， 重要现象没有被描述。这样做的目的 一项研究旨在检测年龄对QT间期和QT间期的影响， 在自主神经阻断前后，两种性别的分散度。 随着年龄的增长，原始QT间期的性别差异已经被证实。 但性别和年龄对QT离散度的相互作用， 未知 40名年轻受试者和40名老年受试者， 结构性心脏病将在普通临床 西北纪念医院研究中心。 受试者将 进行筛查，以确保没有结构性心脏病 禁忌自主神经系统疾病或全身性疾病 堵塞。 在后续访视中，受试者将接受常规12导联 心电图和体表标测图的几个阶段：（1）休息时;（2） 阶段性自行车运动试验;（3）首次服药后， 自主神经阻断方案（阿托品或心得安）;（4） 第二种药物（普萘洛尔或阿托品）;（5）运动试验期间， 给予双重自主神经阻滞。QT间期将 以标准的方式来衡量。 12导联QT离散度 将通过手动和计算机化方法确定EKG 使用之前开发的算法。 QT离散度 将使用定制设计的 这些算法将作为研究的一部分开发。 重复 方差分析的措施将被用来检查差异， 绝对QT间期和年轻人与 老年人自主神经阻滞前后。 此外，性别 还将研究影响。 由于老年人是高风险的 严重的心律失常，了解心肌的演变 复极化作为老化发生的生理过程可能具有 心脏性猝死问题的重要意义 老人 如果年龄改变QT离散度的假设得到证实， 未来的研究将试图评估机制和临床 这一变化对心肌复极化随年龄增长的影响。

Recent studies have suggested that in addition to the absolute duration of the QT interval, the dispersion of the QT interval as measured by differences in the QT interval in different leads on a standard 12 lead ECG may be associated with an adverse prognosis in patients at risk for heart rhythm disturbances. Although several population studies have examined QT dispersion, the effects of aging on this potentially important phenomenon have not been described. The purpose of this study is to examine the effects of aging on the QT interval and QT dispersion in both genders before and after autonomic blockage. Gender differences in the raw QT interval with aging have been described but the interaction of gender and aging on QT dispersion are unknown. Forty young and 40 elderly subjects without evidence of structural heart disease will be evaluated in the General Clinical Research Center at Northwestern Memorial Hospital. Subjects will undergo a screening visit to ensure the absence of structural heart disease or systemic diseases which would contraindicate autonomic blockage. On a subsequent visit, subjects will undergo routine 12 lead ECG and body surface maps at several stages: (1) At rest; (2) During staged bicycle exercise testing; (3) After the first drug of a double autonomic blockage protocol (atropine or propranolol); (4) After the second drug (propranolol or atropine); (5) During exercise testing after the administration of double autonomic blockade. The QT interval will be measured in the standard fashion. QT dispersion on the 12 lead EKG will be determined by both manual and computerized methods using algorithms that have been previously developed. QT dispersion on body surface maps will be analyzed using custom designed algorithms which will be developed as part of the study. Repeated measures of analysis of variance will be used to examine differences in the absolute QT interval and in QT dispersion between the young and elderly before and after autonomic blockade. In addition, gender effects will also be examined. Since the elderly are at high risk for serious arrhythmias, understanding the evolution of myocardial repolarization as aging occurs as a physiologic process may have important implications for the problem of sudden cardiac death in the elderly. If the hypothesis that aging alters QT dispersion if verified, future studies will attempt to evaluate the mechanism and clinical implications of this change in myocardial repolariztion with aging.