Key Points
- Investigate the cellular mechanisms of conduction delay and concealment within the atrioventricular (AV) node and ventricular specialized conduction system during repetitive premature atrial responses.
- Recorded intracellular electrical signals from single cells within the AV node and ventricular specialized conduction system using microelectrodes.
- Delivered serially evoked premature atrial responses across varying cycle lengths and precise excitation intervals.
- Serial premature atrial responses induced conduction delays and block within both the AV node and the ventricular specialized conduction system.
- Decreased preceding cycle length caused rapid shortening of the functional refractory period in ventricular conduction fibers, shifting the site of block for most concealed beats to the AV node.
- A 1-millisecond difference in the excitation timing of a premature atrial response was sufficient to determine whether AV nodal conduction or block occurred.
Structured PICO
PPopulationSingle cells within the AV node and ventricular specialized conduction system (preclinical model)
IInterventionSerially evoked premature atrial responses
OOutcomeAV conduction delays and blocksurrogate
Microelectrode studies demonstrate that minute changes in excitation timing (as small as 1 ms) can determine AV node conduction versus block during premature atrial responses.