Furuya Masaki, Masuda Yuta, Sato Kei, Nishibe Toshihiro, Yana Kazuo, Ono Takuya
Annu Int Conf IEEE Eng Med Biol Soc. 2014;2014:38-41. doi: 10.1109/EMBC.2014.6943523.
This paper examines the long and short term co-variability of QT and RR intervals for diabetic patients to explore if the QT-RR co-variability could yield a noble index for the stratification of clinical severity of the disease. Twenty four hour Holter ECG recordings are made for 19 type 2 diabetic (T2DM) patients and 25 normal subjects. RR and QT intervals are extracted from ECG signals sampled at 200 Hz and their co-variability has been examined. To see the long term QT-RR co-variability, correlation coefficients and mutual entropies between QT and RR intervals have been estimated for original beat to beat intervals and smoothed median interval series of successive one hundred beats. Mutual entropy for both beat-to-beat and smoothed median QT and RR interval series showed statistically significant differences between T2DM and control subjects whereas differences in correlation coefficients showed significant difference only for beat-to-beat intervals. Mutual entropy between both beat-to-beat and smoothed median QT-RR interval sequences showed the equally well separation between T2DM patients and control subjects: Mutual entropy and serial correlation coefficients for beat to beat intervals are respectively 1.42 ± 0.33 (bits), 0.856 ± 0.055 for control and 0.752 ± 0.23 (bits), 0.756 ± 0.10 for T2DM patients. Scatter diagram between RR and QT intervals show apparent nonlinearity which validate this result. Short term QT-RR co-variability has been examined by spline smoothed QTc series and sporadic changes have been observed for the control subjects whereas no such changes are found in diabetic patients. This new phenomenon could be a mean for the clinical characterization of diabetes.
本文研究糖尿病患者QT和RR间期的长期和短期共变性，以探讨QT-RR共变性是否能产生一个用于疾病临床严重程度分层的重要指标。对19名2型糖尿病（T2DM）患者和25名正常受试者进行了24小时动态心电图记录。从以200Hz采样的心电图信号中提取RR和QT间期，并对其共变性进行了研究。为了观察长期QT-RR共变性，对原始逐搏间期以及连续100个搏动的平滑中位数间期序列，估计了QT和RR间期之间的相关系数和互熵。逐搏以及平滑中位数QT和RR间期序列的互熵在T2DM患者和对照受试者之间显示出统计学上的显著差异，而相关系数的差异仅在逐搏间期显示出显著差异。逐搏以及平滑中位数QT-RR间期序列之间的互熵在T2DM患者和对照受试者之间显示出同样良好的区分：逐搏间期的互熵和序列相关系数，对照组分别为1.42±0.33（比特），0.856±0.055，T2DM患者为0.752±0.23（比特），0.756±0.10。RR和QT间期之间的散点图显示出明显的非线性，这证实了该结果。通过样条平滑QTc序列研究了短期QT-RR共变性，观察到对照受试者有偶发变化，而糖尿病患者未发现此类变化。这一新现象可能是糖尿病临床特征化的一种手段。
