Changes of electrophysiological parameters of the heart after the destruction of the epicardial nerve subplexuses of the right atrium

Objectives: of the present study were to verify the topography of the intracardiac nerve subplexuses (INS) by using electrophysiological methods, its relations with sinoatrial (SA) node function and investigate the possibility of selective surgical SA node denervation. Design, Methods and Results: 32 mongrel dogs were used for electrophysiological studies. Nervus subplexuses destructions were performed by electrocoagulation or cryoablation in three zones located around the right superior vena cava: ventral, lateral and dorsal. The sinus rhythm, SA node function recovery time, atrioventricular (AV) node conductivity, the AV node and the atrial effective refractory period were measured. Eight experiments in each of the three zones were performed. The average changes of electrophysiological parameters before and after INS destruction have shown that the destruction of the ventral and lateral zones modifies the effects of sympathetic tone to SA node activity. The destruction of the dorsal zone modifies the effects of the vagus nerve to the SA node. Conclusions: The function of the SA and AV nodes can be modified by the destruction of the ventral, lateral and dorsal zones of the right atrium. It is necessary to point up that while performing interventions and radiofrequency ablations in the zones of nerve plexuses surgeons must be aware of possible changes in SA node’s function because of the impairment of these nerve plexuses and, if possible, to avoid surgical manipulations in these zones.