INTRODUCTION Respiratory sinus arrhythmia (RSA) and heart rate variability (HRV) are parameters of autonomic cardiac innervation. They decrease with age and after atrioventricular nodal modification (AVNM) suggesting vagal denervation in both situations. We hypothesized, however, that AVNM causes only a transient, functional decline in vagal activity, whereas aging causes permanent vagal denervation. A new method of analyzing RSA phase dynamics based on circle maps (CM) can potentially differentiate between both forms of reduced vagal activity. METHODS In 18 younger and 14 older healthy control subjects 24-hour Holter ECGs were recorded for HRV analysis. Repeated measurements of RSA were acquired during paced breathing (PB). In 16 consecutive patients undergoing AVNM the same measurements were applied before, 1 day and 3 months after the procedure. CM were calculated from consecutive RR intervals and the similarity between different CM quantified by the Kullback information gain (KIG). RESULTS HRV analysis revealed lower HF bands, LF bands and RSA amplitudes in older vs. younger control subjects. KIG revealed less similarity between younger and older control subjects than within the respective age groups. After AVNM a decrease in HF bands was noted in HRV analysis. Three months after AVNM, HF bands returned to pre-ablation values. CM obtained before and 1 day after AVNM displayed comparable similarity to CM acquired 1 day before and 3 months after ablation. CONCLUSIONS In contrast to conventional HRV parameters, CM of RSA are not altered by ablation in the posteroseptal space but by aging. Thus, this new method appears to differentiate between transient autonomic modification and chronic denervation.

中文翻译：

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房室结改变后保留副交感神经支配：呼吸性窦性心律不齐的圆形图的证据。

引言呼吸窦性心律不齐（RSA）和心率变异性（HRV）是自主神经支配的参数。随着年龄的增长和房室结改变（AVNM）后，它们均减少，提示在两种情况下均存在迷走神经。然而，我们假设AVNM仅引起迷走神经活动的短暂功能性衰落，而衰老则导致永久性迷走神经失神经。一种基于圆图（CM）分析RSA相动力学的新方法可能会区分迷走神经活动减少的两种形式。方法在18名年轻和14名年龄较大的健康对照组中记录24小时动态心电图进行HRV分析。在定速呼吸（PB）期间重复测量RSA。在连续16例接受AVNM的患者中，之前进行了相同的测量，手术后1天3个月。根据连续的RR间隔计算CM，并通过Kullback信息增益（KIG）量化不同CM之间的相似度。结果HRV分析显示，老年对照组和年轻对照组的HF频段，LF频段和RSA幅度较低。KIG揭示了年轻和年长对照受试者之间的相似性要比相应年龄组内相似。在AVNM后，HRV分析中发现HF频段减少。AVNM后三个月，HF带恢复到消融前的值。AVNM之前和之后1天获得的CM与消融前1天和3个月后获得的CM具有相似的相似性。结论与常规HRV参数相反，RSA的CM不会因后中隔空间的消融而改变，而会因衰老而改变。从而，