London M J
University of Colorado Health Sciences Center, Denver, USA.
J Cardiothorac Vasc Anesth. 1996 Jun;10(4):497-501. doi: 10.1016/s1053-0770(05)80011-4.
Perioperative myocardial ischemia, detected by off-line Holter ST-segment monitoring, has been associated with adverse cardiac outcome. Technical advances in digital signal processing have facilitated development of digital Holter recorders that allow 24- to 48-hour recording, full disclosure storage, and "real-time" quantitative analysis of ST-segment levels. These recorders may be useful for "on-line" clinical detection of perioperative ischemia. However, little data are available, independent of manufacturers' claims, to validate their accuracy. Using a previously validated digital electrocardiogram (ECG) simulator, a commercially available device was evaluated.
Laboratory bench study.
Not applicable.
Not applicable.
Not applicable.
Custom digital ECG waveform templates were programmed for use with a commercially available ECG simulator (M311 ECG simulator; Fogg Systems, Inc, Aurora, CO). For each template, ST-segment morphology (horizontal elevation or depression, downsloping depression), QRS duration (80 v 120 msec) and the presence or absence of a P wave were manipulated, yielding six unique QRS shapes. For each shape, the degree of ST-segment deviation was altered over a wide range. ST-segment values from the simulator (measured at 60 msec after the J point) ranged from +10 to -18 mm. The SEER digital Holter recorder (Marquette Electronics, Milwaukee, WI) was tested. One hundred twenty-six measurements of ST-segment deviation were input to the SEER at each of two testing sessions. The ST-segment value from the recorder in the "noninteractive" analysis mode was obtained, and the two results averaged for comparison with the expected simulator value. Variability of ST-segment measurement over a continuous 1-hour period of simulator input was also assessed. Sixty-seven percent of measurements were within 95% to 100% of expected, whereas 90% were within 90% to 110%. The regression equation for the complete dataset was SEER output (mm) = -0.47 + 1.015 * simulator input, R2 = 0.99. The mean observed-to-expected value ratio was 100% +/- 6% (+/-SD), range 80% to 114%. The mean deviation in millimeters from expected for all measurements was 0.10 +/- 0.20 mm, median 0.05 mm, range -0.25 to +0.60 mm. For the 72 measurements obtained by 5-minute sampling over 1 hour of continuous simulator input for each of the six QRS shapes, the mean percent difference between observed and expected values was 0.5% +/- 4.5%, median 0.0%, with a mean coefficient of variation of 2.7% (median 1.9%).
Using a digital ECG simulator, it was found that the SEER recorder analyzed ST-segment deviation with a high degree of accuracy. These findings, along with its full disclosure reporting capabilities, suggest it may be useful in perioperative risk stratification. However, accuracy in the clinical setting remains to be validated.
通过离线动态心电图ST段监测检测到的围手术期心肌缺血与不良心脏结局相关。数字信号处理技术的进步推动了数字动态心电图记录器的发展，这种记录器能够进行24至48小时的记录、全信息存储以及对ST段水平进行“实时”定量分析。这些记录器可能有助于围手术期缺血的“在线”临床检测。然而，除了制造商的声明外，几乎没有数据可用于验证其准确性。使用先前经过验证的数字心电图（ECG）模拟器，对一种市售设备进行了评估。
实验室台架研究。
不适用。
不适用。
不适用。
为与市售ECG模拟器（M311 ECG模拟器；Fogg Systems公司，科罗拉多州奥罗拉）配合使用，编写了定制的数字ECG波形模板。对于每个模板，对ST段形态（水平抬高或压低、下斜型压低）、QRS波时限（80对120毫秒）以及P波的有无进行操控，产生六种独特的QRS波形。对于每种波形，在很宽的范围内改变ST段偏移程度。模拟器的ST段值（在J点后60毫秒测量）范围为+10至 -18毫米。对SEER数字动态心电图记录器（马奎特电子公司，威斯康星州密尔沃基）进行了测试。在两个测试环节的每一个环节，将126次ST段偏移测量值输入到SEER中。获取记录器在“非交互式”分析模式下的ST段值，并将两个结果平均以与预期模拟器值进行比较。还评估了在模拟器连续输入1小时期间ST段测量的变异性。67%的测量值在预期值的95%至100%范围内，而90%在90%至110%范围内。完整数据集的回归方程为SEER输出（毫米）= -0.47 + 1.015×模拟器输入，R² = 0.99。观察值与预期值的平均比率为100%±6%（±标准差），范围为80%至114%。所有测量值与预期值的平均毫米偏差为0.10±0.20毫米，中位数为0.05毫米，范围为 -0.25至+0.60毫米。对于通过对六种QRS波形中的每一种在模拟器连续输入1小时期间进行5分钟采样获得的72次测量，观察值与预期值之间的平均百分比差异为0.5%±4.5%，中位数为0.0%，平均变异系数为2.7%（中位数为1.9%）。
使用数字ECG模拟器发现，SEER记录器分析ST段偏移具有高度准确性。这些发现及其全信息报告能力表明，它可能在围手术期风险分层中有用。然而，其在临床环境中的准确性仍有待验证。
