Origin and function of intrinsic neural pathways located in the area of pulmonary veins

Abstract

Objectives: The aim of the present study was to verify topography of intrinsic nervous pathways (NP) located in the area of pulmonary veins (PV), and to investigate influence to the function and neural control of heart. Design and Methods: In ten electrophysiological studies with mongrel dogs we bilaterally ligated cervical n. vagus trunks, to avoid cerebral influence and control vagal effects. Isolation of NP was performed on the epicardial surface of the heart, in 6 selected zones of PV by using the standard clinical method of radiofrequency ablation. Protocol of investigation included recording of heart rate, sinus node (SN) function recovery time, AV conductivity, effective refractory periods of the atria, AV node and the ventricles before and after isolation. Results: Isolation in superior right side shows effect of decreased sympathetic tone to all heart parameters with no reliable changes of parasympathetic tone. Isolation in middle right side heightened effects, whereas in inferior right side no changes were observed. Isolation in left superior side shows markedly decreasing or termination of parasympathetic tone, induced by the left n. vagus trunk, although parasympathetic action of the right n. vagus trunk remains. Isolation of middle/inferior left side produce insignificant diminishing of vagus effect pronounced to function of SN and absent to AV conductivity. Conclusions: 1. In superior area of the right PV sympathetic NP are localized mainly influencing the AV node and less to the SN function. 2. In superior area of the left PV parasympathetic NP are localized entering from the left cervical n. vagus trunk influencing AV conductivity and refractoriness of the ventricles. 3. In inferior area of the left PV possibly mixed vagosympathetic NP or sympathetic branch are localized altering SN function.