Role of slow pathway after nodal fast pathway ablation on the basic and rate- dependent properties of the isolated rabbit atrioventricularNode

The aim of this study is to obtain new insight into possible relation between functional properties of slow concealed pathway and rate-dependent properties of AV-node. Rate-dependent nodal properties of recovery, facilitation, and fatigue were characterized by stimulation protocols in one groups of (N=7) isolated superfused AV-Nodal rabbits. Small miniature lesions were made by delivering constant voltage (110 V-100 s) with unipolar silver electrode. Fast pathway ablation significantly decreased facilitation and had no effect on fatigue and nodal refractoriness. The most important effect of fast pathway ablation was prolongation of minimum conduction time. The FP-ablation revealed the presence of the concealed SP. Rate-dependent property of node is dependent to dynamic interaction between concealed slow with slow pathway. Fast pathway involved in the mechanism of facilitation.