Helfenbein Eric D, Zhou Sophia H, Lindauer James M, Field Dirk Q, Gregg Richard E, Wang John J, Kresge Scott S, Michaud Francis P
Advanced Algorithm Research Center, Philips Medical Systems, Milpitas, CA 95035, USA.
J Electrocardiol. 2006 Oct;39(4 Suppl):S123-7. doi: 10.1016/j.jelectrocard.2006.05.018. Epub 2006 Aug 21.
QT interval measurement in the patient monitoring environment is receiving much interest because of the potential for proarrhythmic effects from both cardiac and noncardiac drugs. The American Heart Association and American Association of Critical Care Nurses practice standards for ECG monitoring in hospital settings now recommend frequent monitoring of QT interval when patients are started on a potentially proarrhythmic drug. We developed an algorithm to continuously measure QT interval in real-time in the patient monitoring setting. This study reports our experience in developing and testing this automated QT algorithm. Compared with the environment of resting ECG analysis, real-time ECG monitoring has a number of challenges: significantly more amounts of muscle and motion artifact, increased baseline wander, a varied number and location of ECG leads, and the need for trending and for alarm generation when QT interval prolongation is detected. We have used several techniques to address these challenges. In contiguous 15-second time windows, we average the signal of tightly clustered normal beats detected by a real-time arrhythmia-monitoring algorithm to minimize the impact of artifact. Baseline wander is reduced by zero-phase high-pass filtering and subtraction of isoelectric points as determined by median signal values in a localized region. We compute a root-mean-squared ECG waveform from all available leads and use a novel technique to measure the QT interval. We have tested this algorithm against standard and proprietary ECG databases. Our real-time QT interval measurement algorithm proved to be stable, accurate, and able to track changing QT values.
在患者监测环境中，QT间期测量备受关注，因为心脏药物和非心脏药物都有可能产生促心律失常作用。美国心脏协会和美国重症护理护士协会关于医院环境中心电图监测的实践标准现在建议，当患者开始使用可能具有促心律失常作用的药物时，应频繁监测QT间期。我们开发了一种算法，可在患者监测环境中实时连续测量QT间期。本研究报告了我们在开发和测试这种自动QT算法方面的经验。与静息心电图分析环境相比，实时心电图监测存在许多挑战：肌肉和运动伪影明显更多、基线漂移增加、心电图导联数量和位置各不相同，以及在检测到QT间期延长时需要进行趋势分析和生成警报。我们使用了多种技术来应对这些挑战。在连续的15秒时间窗口内，我们对通过实时心律失常监测算法检测到的紧密聚集的正常搏动信号进行平均，以尽量减少伪影的影响。通过零相位高通滤波和减去由局部区域中的信号中值确定的等电位点来减少基线漂移。我们从所有可用导联计算均方根心电图波形，并使用一种新技术来测量QT间期。我们已针对标准和专有心电图数据库对该算法进行了测试。我们的实时QT间期测量算法被证明是稳定、准确的，并且能够跟踪变化的QT值。
