自主神经对心脏房室传导调节的动态分析

尽管自主神经对心脏房室传导的作用报道很多，但自主神经对房室传导的动力学特性仍未被揭示。本实验通过模板匹配方法从His束电图检测A、H、V波并测量两心房间期(AA)、心房波与H波间期(AH)、H波与心室波间期(HV)和心房波与心室波间期(AV)，通过白噪声技术动力性刺激迷走神经、交感神经或心房起搏时AV间期的传递函数变化，研究动态自主神经刺激对房室传导的动态调节。结果如下：AV间期对迷走神经刺激呈一阶低通滤波性质，起搏时AV间期增益(13．2％)较未起搏时明显增高(4．6％，P＜0．05)；AV间期对交感神经刺激呈二阶低通滤波性质，起搏时AV间期增益(46％)较未起搏时明显增高(32％，P＜0．05)；动力性起搏心房，从间期与AV间期呈良好负相关。因此认为：(1)AV间期对迷走神经或交感神经刺激均呈现出低通滤波性质。(2)心脏的房室传导时间与心动周期长度呈线性负相关。心率的改变增强交感或迷走神经对房室传导的动力性作用，心率对房室传导的作用在迷走刺激时较交感刺激时强。这在房室传导对自主神经动力性调节的反应时保持相对稳定具有重要的生理意义。

DYNAMIC ANALYSIS OF AUTONOMIC REGULATION OF ATRIOVENTRICULAR CONDUCTION

Although the characteristics of static interaction between autonomic nervous system and heart rate in regulating AV conduction have been well studied, yet the influence of dynamic vagal or sympathetic nerve stimulation on AV conduction remains unknown. We therefore measured the cardiac cycle length (AA interval) and AV conduction time (AV interval) on His bundle electrogram by a template matchingalgorithm, and investigated the dynamic modulation by estimating the transfer function of autonomic nerve stimulation and AV interval and the transfer functionof AA interval and AV interval using a band limited Gaussian white noise technique. The transfer function relating dynamic vagal stimulation to AV interval had characteristics of a first order low pass filter. Tonic vagal stimulation at unpacing rate and pacing rate increased the gain of transfer function by 4.6% and 13.2%, respectively ( P<0.05 ). The transfer function from dynamic sympathetic stimulation to AV interval had characteristics of a second order low pass filter. Tonic sympathetic stimulation at unpacing and pacing rate increased the gain by 32% and 46%, respectively ( P<0.05 ). Tonic pacing of heart rate had a negative of the phase between AA interval and AV interval. So we conclude that (1) AV conduction responds as a low pass filter to fluctuations in either vagal or sympathetic tone; (2) There is a negative linear relation between cardiac cycle length and AV conduction time; (3) The changes of heart rate influence the dynamic effect of either vagal or sympathetic tone on AV conduction. The effect of heart rate on AV conduction is larger in vagal tone than in sympathetic tone. By virtue of this rate dependent property, AV conduction appears to keep certain dynamic range in response to autonomic nervous system.