Tarkiainen Tuula H, Kuusela Tom A, Tahvanainen Kari U O, Hartikainen Juha E K, Tiittanen Pekka, Timonen Kirsi L, Vanninen Esko J
Department of Clinical Physiology and Nuclear Medicine, Kuopio University Hospital and University of Kuopio, Kuopio, Finland.
Clin Physiol Funct Imaging. 2007 Mar;27(2):126-33. doi: 10.1111/j.1475-097X.2007.00726.x.
Non-linear heart rate (HR) dynamics characterizes the fractal properties and complexity of the variations in HR. Ventricular and supraventricular ectopic beats might introduce a mathematical artefact to the analyses on sinus rhythm. We therefore evaluated the effects of different editing practices for ectopic beats such that 753 40-min ECG recordings were (i) not edited for the ectopic beats, or the ectopic beats were edited with (ii) an interpolation or with (iii) a deletion method before the analyses of non-linear HR dynamics. The non-linear HR dynamics analyses included detrended fluctuation analysis (DFA), approximate entropy, symbolic dynamics (SymDyn), fractal dimension and return map (RM). We found that the short-term scaling exponent (alpha1) of DFA, forbidden words of SymDyn and RM were sensitive measurements to the ectopic beats and there were strong correlations between these measurements and the number of ectopic beats. In addition, the unedited ectopic beats significantly lowered the stability of these measurements. However, the editing either with interpolation or deletion method corrected the measurements for the bias caused by the ectopic beats. On the contrary, the entropy measurements were not as sensitive to the ectopic beats. In conclusion, the ectopic beats affect the non-linear HR dynamics of sinus rhythm differently, causing a more marked bias in fractal than in complexity measurements of non-linear HR dynamics. This erroneous effect of ectopic beats can be corrected with a proper editing of these measurements. Therefore, there is an obvious need for standardized editing practices for ectopic beats before the analysis of non-linear HR dynamics.
非线性心率（HR）动力学表征了心率变化的分形特性和复杂性。室性和室上性异位搏动可能会给窦性心律分析带来数学伪影。因此，我们评估了不同的异位搏动编辑方法的效果，在对非线性HR动力学进行分析之前，对753份40分钟的心电图记录进行如下处理：（i）不对异位搏动进行编辑，或（ii）采用插值法或（iii）删除法对异位搏动进行编辑。非线性HR动力学分析包括去趋势波动分析（DFA）、近似熵、符号动力学（SymDyn）、分形维数和返回映射（RM）。我们发现，DFA的短期标度指数（alpha1）、SymDyn的禁词和RM对异位搏动是敏感的测量指标，并且这些测量指标与异位搏动的数量之间存在强相关性。此外，未编辑的异位搏动显著降低了这些测量指标的稳定性。然而，采用插值法或删除法进行编辑可校正由异位搏动引起的偏差对测量指标的影响。相反，熵测量指标对异位搏动不太敏感。总之，异位搏动对窦性心律的非线性HR动力学有不同影响，在非线性HR动力学的分形测量中比在复杂性测量中造成更明显的偏差。通过对这些测量指标进行适当编辑，可以校正异位搏动的这种错误影响。因此，在分析非线性HR动力学之前，显然需要对异位搏动进行标准化的编辑操作。
