Leffler C T, Saul J P, Cohen R J
Division of Health Sciences and Technology, Harvard University-Massachusetts Institute of Technology, Cambridge.
J Cardiovasc Electrophysiol. 1994 Jan;5(1):2-15. doi: 10.1111/j.1540-8167.1994.tb01109.x.
Atrioventricular (AV) conduction time varies on a beat-by-beat basis in response to the influences of cardiac efferent autonomic activity and rate-dependent electrical recovery processes. The goals of this study were to distinguish these effects on AV conduction time and to compare the variability in sinoatrial and AV nodal function.
The PR interval on the surface ECG served as an index of AV conduction time in this study of 14 adult human subjects undergoing a random interval breathing protocol. P and R waves were located by a template-matching algorithm. Spectral analysis allowed frequency-domain comparisons between PR and RR interval variability. Spectra of PR and RR intervals had similar power distributions, although the power of the RR interval spectra was much greater. Autonomic blockade with atropine plus propranolol reduced the power of both spectra. Standing significantly decreased the spectral power from 0.15 to 0.5 Hz for PR and RR spectra, and introduced a peak near 0.1 Hz in the mean PR and RR spectra, although the latter finding was significant only for the RR interval spectra. Propranolol had no significant effects on the PR and RR interval spectra. Linear regression analysis allowed quantification of the autonomic and recovery effects on AV conduction and showed which effect predominated. Simple linear regression confirmed in adults a previous finding in children that conduction time may be either positively or negatively correlated with cycle length. By multiple regression and transfer function analysis, the inverse relation seen in some subjects was attributed to the effect of recovery from the preceding cycle. With the preceding recovery period accounted for, the conduction time and cycle length of the current beat were positively correlated, presumably due to the parallel autonomic effects on the sinoatrial and AV nodes. The magnitude of the recovery effect predicted by the regression analysis was similar to published values.
A noninvasive evaluation of the surface ECG can be used to compare variability in AV conduction time and cycle length and characterize the effects of autonomic efferent activity and rate-related recovery on AV nodal function.
房室（AV）传导时间逐搏变化，以响应心脏传出自主神经活动和心率依赖性电恢复过程的影响。本研究的目的是区分这些对房室传导时间的影响，并比较窦房结和房室结功能的变异性。
在这项对14名成年受试者进行随机间隔呼吸方案的研究中，体表心电图上的PR间期用作房室传导时间的指标。P波和R波通过模板匹配算法定位。频谱分析允许对PR间期和RR间期变异性进行频域比较。PR间期和RR间期的频谱具有相似的功率分布，尽管RR间期频谱的功率要大得多。阿托品加普萘洛尔进行自主神经阻滞降低了两个频谱的功率。站立显著降低了PR和RR频谱从0.15至0.5Hz的频谱功率，并在平均PR和RR频谱中引入了一个接近0.1Hz的峰值，尽管后一发现仅对RR间期频谱有显著意义。普萘洛尔对PR和RR间期频谱无显著影响。线性回归分析允许对自主神经和恢复对房室传导的影响进行量化，并显示哪种影响占主导。简单线性回归在成年人中证实了先前在儿童中的发现，即传导时间可能与心动周期长度呈正相关或负相关。通过多元回归和传递函数分析，在一些受试者中看到的反向关系归因于前一周期恢复的影响。在前一恢复周期得到考虑的情况下，当前搏动的传导时间和心动周期长度呈正相关，可能是由于自主神经对窦房结和房室结的平行影响。回归分析预测的恢复效应大小与已发表的值相似。
体表心电图的无创评估可用于比较房室传导时间和心动周期长度的变异性，并表征自主神经传出活动和心率相关恢复对房室结功能的影响。
