[Role of the vagus nerve in the origination and cessation of atrial tachyarrhythmias].
At the root of the mechanism of supraventricular tachyarrhythmias observed in an isolated atrium following electric stimulation of the vagus nerve lies circulation of the excitation wave or waves. The origination of this circulation is due to a normalized conduction in the regions inhibited by the vagus nerve, the existence of such regions having been shown in experiments. The trajectory of the circulating excitation wave was reproduced with the help of a mathematical model the properties of whose elements had been pre-set axiomatically. The forecasts and effects of the model were verified in tests involving the use of the microelectrode technique. The question as to the applicability of the proposed model for explaining the mechanism causing the development of disorders in the cardiac rhythm at the time of myocardial infarction is discussed. The inhibited regions develop not only on stimulation of the extracardiac vagus, but also after direct stimulation of the myocardium. Direct tests demonstrated that the activation of the intramural nerves is apt to suppress disturbances of the rhythm, occasioned by the circulating excitation and ectopic activity. It is suggested that the excitation of the intracardiac nerves during electric defibrillation may appear as an additional factor causing a positive antiarrhythmic effect of the condensator discharge.