Imam Mohammad H, Karmakar Chandan K, Khandoker Ahsan H, Palaniswami Marimuthu
Annu Int Conf IEEE Eng Med Biol Soc. 2013;2013:2559-62. doi: 10.1109/EMBC.2013.6610062.
Perturbations in the normal heart rate are generally represented by the presence of premature activation (PA) beats in the surface electrocardiogram (ECG). The presence of PA is one of the main reasons of instability in QT dynamics which could initiate arrhythmia. Analyzing Boundary-Input Boundary-Output (BIBO) stability of the short term linear autoregressive QT-RR model is a way of detecting instability in QT dynamics from the ECG. The aim of this paper is to investigate if PA is the only reason for instability in the ventricular repolarisation process, which is denoted by QT interval of surface ECG. Ten healthy subjects with normal sinus rhythm and seven patients with sustained ventricular tachycardia (VT) were analyzed in this study. 10 min long ECG data were collected from each subject of the healthy group and 10 min ECG before the start of VT were taken for each subject of the VT group. Autoregressive QT-RR model was derived for each non-overlapping 1 min long ECG segment of the 10 min long ECG data. Instability in QT dynamics was quantified by measuring the numbers of unstable segments in ECG data for each subject ( ). Results of this study revealed that like the VT group subjects, QT instability detected by QT-RR model is also found in healthy subjects whose ECG segments are mostly free from PA beats. This finding indicates that BIBO unstable QT characteristics might arise from other inherent factors of cardiovascular system in addition to PA.
正常心率的扰动通常由体表心电图（ECG）中过早激活（PA）搏动的存在来表示。PA的存在是QT动态不稳定的主要原因之一，可能引发心律失常。分析短期线性自回归QT-RR模型的边界输入-边界输出（BIBO）稳定性是一种从ECG检测QT动态不稳定的方法。本文的目的是研究PA是否是心室复极过程不稳定的唯一原因，心室复极过程由体表ECG的QT间期表示。本研究分析了10名窦性心律正常的健康受试者和7名持续性室性心动过速（VT）患者。从健康组的每个受试者收集10分钟长的ECG数据，从VT组的每个受试者在VT开始前采集10分钟的ECG。针对10分钟长的ECG数据的每个不重叠的1分钟长的ECG片段推导出自回归QT-RR模型。通过测量每个受试者的ECG数据中不稳定片段的数量来量化QT动态的不稳定性（ ）。本研究结果表明，与VT组受试者一样，在ECG片段大多无PA搏动的健康受试者中也发现了由QT-RR模型检测到的QT不稳定性。这一发现表明，除PA外，BIBO不稳定的QT特征可能还源于心血管系统的其他内在因素。
