EFFECT OF AGING ON MYOCARDIAL REPOLARIZATION

本研究的目的是探讨年龄对自主神经阻滞前后两性QT间期和QT离散度的影响。原始AT反转与年龄的性别差异已被描述，但性别和年龄对QT离散度的相互作用尚不清楚。40名无结构性心脏病证据的年轻人和40名老年人将在西北纪念医院的综合临床研究中心进行评估。受试者将接受筛选访问，以确保没有结构性心脏病或全身性疾病，这些疾病将禁止自主神经阻滞。在随后的访问中，受试者将在几个阶段进行常规的12导联心电图和体表图：(1)休息时；(2)阶段自行车运动试验；(3)双自主神经阻断方案（阿托品或心得安）首药后；(4)第二种药物（心得安或阿托品）后；(5)双自主神经阻滞后的运动试验。QT间期将以标准方式测量。12导联心电图的QT离散度将通过人工和计算机方法确定，使用先前开发的算法。体表图上的QT离散度将使用定制设计的算法进行分析，该算法将作为研究的一部分而开发。反复测量方差分析将用于检查自主神经阻滞前后青年和老年人绝对QT间期和QT离散度的差异。此外，还将审查性别影响。

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 blockade. Gender differences in the raw AT inverval with aging have been described but the interaction of gender and aging on QT dispersion are unknown. Forty young and forty 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 blockade. 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 blockade 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.