Key Points
- This research aims to explore patterns of atrial activation and sinoatrial transmission during spontaneous rhythm in the rabbit heart.
- Intracellular microelectrodes and small unipolar leads were used on the right atrial endocardial surface in vitro.
- Atrial activation and wave patterns were monitored during spontaneous sinus activity.
- The relationship between pacemaker firing and extracellular potentials was analyzed.
- Atrial activation featured a primary negative wave appearing 20-40 msec post pacemaker firing.
- Two sources of multiphasic waves were identified: one from transitional sinus tissue causing low-voltage waves and another from crista terminalis muscle around the invasion region.
- No extracellular wave correlated with true pacemaker firing; the SARB exhibited biphasic deflection after activation of the adjoining muscle.
Structured PICO
PPopulationRabbit heart in vitro (endocardial surface of the right atrium)
IInterventionIntracellular microelectrodes and small unipolar leads applied to endocardial surface
OOutcomeExtracellular wave patterns recorded from the neighborhood of the cardiac pacemaker during spontaneous activitysurrogate
The study maps the complex extracellular wave patterns of sinoatrial transmission in the rabbit heart, questioning the functional role of the sinoatrial ring bundle as an internodal preferential pathway.