Evaluation of Cardiac Autonomic Modulation Using Symbolic Dynamics After Cardiac Transplantation

Abstract Objective: To characterize the behavior of cardiac autonomic modulation in individuals with different times after orthotopic heart transplantation (HTx) using symbolic dynamics analysis. Methods: Sixty patients were evaluated after HTx. We recorded their instantaneous R-R intervals (RRi) by cardiac monitor Polar® RS800CX™ (Polar Electro Oy, Kempele, Finland) for 10 minutes. The same sequence of RRi with 256 consecutive beats was used to perform spectral analysis and symbolic dynamics analysis. We used hierarchical clustering to form groups. One-way analysis of variance (ANOVA) (with Holm-Sidak method) or one-way Kruskal-Wallis test (with Dunn´s post-hoc test) was used to analyze the difference between groups. Linear correlation analysis between variables was performed using Pearson’s or Spearman’s tests. P-value < 0.05 was considered statistically significant. Results: The 0V% index increased, the 2UV% index and the normalized complexity index decreased with an increase of HTx postoperative time. There were a negative correlation between complexity indexes and 0V% and a positive correlation between complexity indexes and 2UV%. Conclusion: Symbolic dynamics indexes were able to show a specific cardiac autonomic modulation pattern for HTx recipients with different postoperative times.

摘要 研究目的：采用符号动力学分析方法，对原位心脏移植（orthotopic heart transplantation, HTx）术后不同时间节点的患者的心脏自主神经调控行为进行特征分析。
研究方法：共纳入60名心脏移植术后患者，使用芬兰肯佩莱 Polar Electro Oy 公司生产的 Polar® RS800CX™ 心脏监护仪，记录受试者10分钟的瞬时R-R间期（RRi）。选取包含256次连续心搏的RRi序列，分别开展频谱分析与符号动力学分析。采用系统聚类法进行分组；组间差异比较采用单因素方差分析（ANOVA，结合Holm-Sidak校正法）或单因素Kruskal-Wallis检验（结合Dunn事后检验）；变量间线性相关分析采用Pearson相关检验或Spearman相关检验。以P值<0.05作为统计学显著性的判定标准。
研究结果：随着心脏移植术后时间的延长，0V%指数升高，2UV%指数与归一化复杂度指数均出现下降；复杂度指数与0V%呈负相关，与2UV%呈正相关。
研究结论：符号动力学指数可清晰呈现不同术后时间跨度的心脏移植受者所特有的心脏自主神经调控模式。