Unified rate-dependent atrioventricular nodal function: Consistent recovery and fatigue properties revealed with S1S2S3 protocols and different recovery indexes

S1S2S3 protocols reveal consistent nodal recovery and fatigue properties regardless of recovery index used. Changes in nodal function curves arising from the use of different recovery indexes mainly depend on pretest effects. This study provides a new approach to a unified interpretation of nodal recovery and fatigue properties.