Effects of single vagal stimuli on heart rate and atrioventricular conduction

Paradoxical dynamic interaction of heart period and vagal activity on atrioventricular conduction in the dog.

“…1 Thus, a generalized increase in vagal activity at the sinoatrial (SA) and AV nodes results in two oppositely directed effects on AV conduction time (the AV interval): (1) the acetylcholine (ACh) released will prolong the AV interval via a direct effect on the AV node, and (2) it will indirectly decrease the AV interval by increasing heart period (AA interval), primarily an AV nodal effect. 2 I wished here to define quantitatively the interaction between these two responses.…”

Zależność między entropią aproksymacji rytmu serca a strukturalną i funkcjonalną przebudową przedsionków oraz przebiegiem klinicznym napadowego i przetrwałego migotania przedsionków

“…However, in most instances, recognition of a specific autonomic pattern is difficult; also, when HRV analysis was used to characterize the role of the autonomic nervous system before AF onset, contrasting results were noticed [24]. The complexity of the problem might be partially explained by the fact that both sympathetic and vagal activation may exert a pro-arrhythmic action by affecting atrial action potential duration and conduction velocity [25,26]; nonuniform autonomic innervation of the atria may also play a critical role [27].…”

Rapid Cardiac Adaptation to Exercise Demand Signal and Execution of Maximal Leg Muscle Contraction.

“…These findings suggest that the timing of vagal nerve activation before ventricular depolarization is important in causing the increase in cardiac interval in response to the exercise demand sig- nal. Levy et al [12] reported that when the vagal nerve is stimulated electrically in anesthetized dogs, the latent period between vagal stimuli and the next atrial depolarization can be longer than 200 ms. If we employed this value as a latent period for humans in this study, the vagal nerve activation had to occur within 228 ms after the onset of exercise demand signal (indicated by a heavy dotted line in Fig.…”