CORE--AMBULATORY ELECTROCARDIOGRAMS

动态心电图核心的主要职责是为其他项目提供分析支持，这些项目旨在评估空气污染对心律失常易损性的影响。心电图将根据常规终点（包括心律、st段和QRST形态）以及自主神经张力和心脏易感性进行评估。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，分析将直接用于测量空气污染对记录在案的心肌梗死患者的影响，并根据需要对后续组进行测量。对于项目2，核心将是心脏病学专业知识的资源。项目三的分析将提供有关空气污染对自由生活长者的影响的资料。心率变异提供了一种自主平衡的测量，这是影响心脏易损性的重要因素，也是空气污染有害影响的可能中介。t波交替是该波形的面积和形态的逐拍变化，在许多实验研究中显示，在各种生理和药物干预期间，t波交替可以预测心室颤动。临床研究表明，HRV和T波交替在不同形式心脏病的危险分层中是有价值的。动态BCO数据将使用高容量、最先进的MARS Unity工作站进行分析，该工作站运行经过验证的软件，可用于所有标准ECG端点和时域和频域的HRV分析。我们最近开发并验证了用于t波复杂解调的软件，以量化交替水平，并将该方法应用于心绞痛和无症状缺血的门诊患者的记录中。因此，随着该系统的可用性以及在使用该系统方面经验丰富的人员的参与，将有可能处理和分析项目1和项目3生成的大量ECG数据。最终，这种全面的以假设为导向的ECG分析方法应该为空气污染对心脏易损性的影响提供重要的见解，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.