[The role of the interatrial septum in development of supraventricular tachyarrhythmias of vagal origin in dogs]. / Rol' mezhpredserdnoi peregorodki v razvitii supraventriculiarnykh takhiaritmii vagusnoi prirody u sobak.

Patterns of atrial activation of ectopic pulse source during vagal stimulation were studied on atrial epicardial surface and atrial septum in mongrel dogs. Epicardial activation maps were drafted. The findings show that, irrespective of preferred direction of conduction in the atria and septum, the entire atrial myocardium acted as a conducting system. Mapping of the first extrasystolic beats during tachyarrhythmias induced with vagal stimulation, has shown their ectopic origin. The data obtained confirms the suggestion that atrial fibrillation may be due to a single source of arrhythmia in septal area.

[Comparison of atrial premature depolarization topography during vagal stimulation and humoral acetylcholine administration]. / Sravnenie topografii vozniknoveniia predserdnykh ékstravozbuzhdenii pri stimuliatsii vagusa i gumoral'nom vozdeistvii atsetilkholina.

Epicardial atrial mapping in open-chest dogs during different cholinergic influences has shown that, in acetylcholine administration and vagal stimulation, spatial distribution of atrial premature depolarisation (APDs) seems to be similar to prevalence of ectopic sources from both atria and atrial septum. Spatial distribution of the APDs in acetylcholine administration in the sinus node artery was limited to the region of this artery so that the APDs mainly arise from intercaval area of the right atrium and from atrial septum, but never from the left atrium. The latent pacemakers spread over both atria and atrial septum, could participate in initiation of cholinergically-induced APDs and atrial fibrillation. A direct effect of acetylcholine seems to be necessary for development of arrhythmic activity of the latent pacemakers.

[Multielectrode mapping study of proarrhythmic vagal effects in the dog atria]. / Issledovanie metodom mnogokanal'nogo kartirovaniia aritmogennogo deistviia bluzhdaiushchikh nervov v predserdiiakh sobaki.

Epicardial mapping (254 unipolar electrodes) of the dog heart both atria was performed to determine spatial distribution of arrhythmic events. The mapping showed that the first atrial premature depolarisation (APD) emerged from ectopic foci, it showed also specific multifocal patterns suggesting a septal source of tachycardia. The data obtained suggests that vagal stimulation (VS) induces focal ectopic APDs, that APDs and escape beats may be due to the same mechanism of spontaneous depolarization in the absence of a reset from dominant rhythm, that a single VS-induced APD is sufficient for initiation of a reentrant atrial fibrillation.