Corino V D A, Belletti S, Terranova P, Lombardi F, Mainardi L T
Department of Bioengineering, Politecnico di Milano, Via Golgi 39, 20131 Milano, Italy.
Methods Inf Med. 2010;49(5):516-20. doi: 10.3414/ME09-02-0035. Epub 2010 Jun 7.
During atrial fibrillation (AF), ventricular response is highly irregular and thus the beat-to-beat variation of blood pressure is increased because of variations in filling time and in contractility.
Aim of the present study is to investigate the short-term dynamics of RR and SAP series in patients with AF, during rest and tilt, and after restoration of sinus rhythm.
We computed symbolic sequences of the three phases, as they retain important features of the dynamics generated by the underlying control system. Then we applied a method based on rank order statistics of symbolic sequences to investigate the profile of different types of dynamics. The linguistic distance (range 0-1) between sequences represents a measure of similarity to assess whether the different physiological states are reflected on the dynamics of RR and SAP series.
The distance between rest and tilt phases is 0.06 ± 0.02 for RR series, meaning they are very similar, while it is 0.21 ± 0.13 for SAP series, showing a difference in the short-term dynamics. RR mean decreases during tilt (738 ± 164 vs. 692 ± 152 ms, p <0.05, rest vs. tilt), while mean SAP is not significantly different (101 ± 20 vs. 104 ± 14 mmHg, rest vs. tilt). Comparing AF and sinus rhythm, both RR and SAP series result different in terms of the computed distance.
SAP short-term dynamics seem to significantly change when comparing rest and tilt phases, while RR series remain unchanged. Moreover, RR mean but not SAP series significantly decreases during tilt.
在心房颤动（AF）期间，心室反应高度不规则，因此由于充盈时间和收缩性的变化，血压的逐搏变化会增加。
本研究的目的是调查AF患者在静息、倾斜以及恢复窦性心律后的RR和收缩期动脉压（SAP）系列的短期动态变化。
我们计算了三个阶段的符号序列，因为它们保留了基础控制系统产生的动态变化的重要特征。然后，我们应用一种基于符号序列秩次统计的方法来研究不同类型动态变化的特征。序列之间的语言距离（范围为0 - 1）代表一种相似性度量，以评估不同的生理状态是否反映在RR和SAP系列的动态变化上。
RR系列在静息和倾斜阶段之间的距离为0.06±0.02，这意味着它们非常相似，而SAP系列的距离为0.21±0.13，表明短期动态变化存在差异。倾斜期间RR平均值下降（静息与倾斜：738±164 vs. 692±152毫秒，p<0.05），而平均SAP无显著差异（静息与倾斜：101±20 vs. 104±14毫米汞柱）。比较AF和窦性心律时，RR和SAP系列在计算出的距离方面均有差异。
比较静息和倾斜阶段时，SAP短期动态变化似乎有显著改变，而RR系列保持不变。此外，倾斜期间RR平均值显著下降，但SAP系列无显著变化。
