CORE--AMBULATORY ELECTROCARDIOGRAMS

动态心电图核心的主要职责是为其他旨在评估空气污染对心律失常脆弱性影响的项目提供分析支持。将评估ECG的常规终点（包括心律和ST段和QT形态）以及自主神经张力和心脏易损性。后者将分别使用心率变异性（HRV）和T波交替的频谱分析技术来确定。在项目#1的情况下，分析将直接测量空气污染对最初有记录的心肌梗死患者的影响，并根据需要测量后续组的影响。对于项目2，核心将是心脏病学的专业知识资源。至于项目3，分析将提供有关空气污染对自由生活的老年人的影响的信息。心率变异性提供了一个衡量自主神经平衡的指标，是影响心脏脆弱性的一个重要因素，也是空气污染有害影响的一个可能的中介。T波电交替是该波形的面积和形态的逐拍变化，并且在许多实验研究中已经显示在不同的生理和药物干预期间预测心室颤动。心率变异性和T波交替在临床研究中已被证明在不同形式的心脏疾病的危险分层中是有价值的。 将使用高容量、最先进的MARS Unity工作站分析动态BCO数据，该工作站运行经验证的软件，用于所有标准ECG终点以及时域和频域的HRV分析。我们最近开发并验证了软件的复杂解调的T波，以量化交替的水平，并已采用的方法记录的门诊患者心绞痛和无症状缺血。因此，随着该系统的可用性以及在其使用方面具有丰富经验的个人的参与，将有可能处理和分析将由项目1和3生成的大量ECG数据。最终，这种全面的假设导向的心电图分析方法应该提供关于空气污染对心脏脆弱性影响的重要见解，并有助于阐明潜在的机制。

The main responsibility for the Ambulatory ECG Core is to provide analytical support for other projects which are designed to assess the impact of air pollution on vulnerability to cardiac arrhythmias. The ECG will be assessed both in terms of conventional endpoints including heart rhythm and ST-segment and QRST morphology, and for autonomic tone and cardiac vulnerability. The latter will be determined using the spectral analytical techniques of heart rate variability (HRV) and T-wave alternans, respectively. In the case of Project #1, the analyses will be directed to measuring the effects of air pollution on patients with documented myocardial infarction initially, and for subsequent groups as required. For Project 2, the Core will be a resource of expertise in cardiology. For Project 3, the analyses will provide information concerning the effect of air pollution on the free-living elderly. HRV provides a measure of autonomic balance, an important factor influencing cardiac vulnerability and a possible mediator of the deleterious influences of air pollution. T-wave alternans is a beat-by-beat variation in the area and morphology of that waveform and has been shown in numerous experimental studies to be predictive of ventricular fibrillation during diverse physiologic and pharmacologic interventions. HRV and T- wave alternans have been shown in clinical investigations to be valuable in risk stratification in diverse forms of cardiac disease. Ambulatory BCO data will be analyzed with a high capacity, state-of-the-art MARS Unity Workstation, which runs validated software for all of the standard ECG endpoints and for HRV analysis in time and frequency domains. We have recently developed and validated the software for complex demodulation of the T-wave to quantify the level of alternans and have employed the method in records of ambulatory patients with angina and silent ischemia. Thus, with the availability of this system and the involvement of individuals who are highly experienced in its use, it will -be possible to process and analyze sizeable numbers of ECG data which will be generated by Projects l & 3. Ultimately, this comprehensive hypothesis- directed approach to ECG analysis should provide important insights regarding the effects of air pollution on cardiac vulnerability and should help to elucidate the underlying mechanisms.