Castiglioni Paolo, Lazzeroni Davide, Coruzzi Paolo, Faini Andrea
Annu Int Conf IEEE Eng Med Biol Soc. 2020 Jul;2020:710-713. doi: 10.1109/EMBC44109.2020.9176704.
Recent developments of detrended fluctuation analysis (DFA) provide multifractal/multiscale (MFMS) descriptions of the heart rate self-similarity, a promising approach to cardiovascular complexity. However, it is unclear whether the MFMS DFA may also describe the nonlinear components of heart rate variability. Our aim is to define MFMS DFA indices for quantifying the short-term and long-term degree of the heart-rate nonlinearity and to apply these indices to detect possible sex-related differences.We recorded the inter-beat-interval (IBI) series in 42 male and in 42 female healthy participants sitting at rest for about 2 hours. For each series j, we generated 100 phase-randomized surrogate series. We applied the MFMS DFA to estimate the self-similarity coefficients α over scales τ between 8 and 512 s and moment orders q between -5 and +5, obtaining coefficients for the original series, α (q, τ), and for each surrogate, α (q, τ) with 1≤i≤100. We first evaluated π(q, τ), percentile of α (q, τ) distribution in which was α (q, τ). Then we calculated the percentages of scales where π(q, τ) was <5% for 8≤τ≤16 s (short-term nonlinearity index NL(q)) and for 16≤τ≤512 s (long-term nonlinearity index NL(q)). We found that NL(q) was generally greater than 50% at all q≥0 but q=2 (i.e., moment order of the monofractal DFA), while at q<0 it was high in males only, with significant sex differences at q=-1 and q=-2. Results indicate that the multifractal DFA may highlight nonlinear heart-rate components at the short scales that are not revealed by the traditional monofractal DFA and that appear related to gender differences.Clinical Relevance- This supports the use of MFMS DFA to integrate the linear information from traditional spectral methods of heart rate variability in clinical studies aimed at improving the stratification of the cardiovascular risk.
去趋势波动分析（DFA）的最新进展提供了心率自相似性的多重分形/多尺度（MFMS）描述，这是一种研究心血管复杂性的很有前景的方法。然而，尚不清楚MFMS DFA是否也能描述心率变异性的非线性成分。我们的目的是定义MFMS DFA指数，以量化心率非线性的短期和长期程度，并应用这些指数来检测可能存在的性别差异。我们记录了42名男性和42名女性健康参与者静息约2小时的逐搏间期（IBI）序列。对于每个序列j，我们生成了100个相位随机替代序列。我们应用MFMS DFA来估计8至512秒尺度τ之间以及-5至+5阶矩q之间的自相似系数α，得到原始序列的系数α（q，τ）以及每个替代序列的系数α（q，τ）（1≤i≤100）。我们首先评估π（q，τ），即α（q，τ）在α（q，τ）分布中的百分位数。然后我们计算了8≤τ≤16秒（短期非线性指数NL（q））和16≤τ≤512秒（长期非线性指数NL（q））时π（q，τ）<5%的尺度百分比。我们发现，在所有q≥0但q = 2（即单分形DFA的阶矩）时，NL（q）通常大于50%，而在q<0时，仅在男性中较高，在q = -1和q = -2时存在显著的性别差异。结果表明，多重分形DFA可能会突出传统单分形DFA未揭示的短尺度心率非线性成分，且这些成分似乎与性别差异有关。临床意义——这支持在旨在改善心血管风险分层的临床研究中使用MFMS DFA来整合来自传统心率变异性谱方法的线性信息。
