Key Points
- Investigate whether electrical excitation can transmit ephaptically between closely apposed ventricular myocardial preparations in vitro.
- Examined pairs of closely apposed cylindrical ventricular myocardial preparations isolated from ferrets in vitro.
- Electrically paced one preparation while elevating extracellular resistance to create longitudinal extracellular potential differences across electrodes spaced 80 µm apart.
- Ephaptic impulse transmission occurred when extracellular potential differences exceeded 30–60 mV, exhibiting bidirectional conduction in 2 of 8 preparation pairs with latencies between 9 and 369 ms.
- Rate-dependent conduction blocks, including the Wenckebach phenomenon, emerged at stimulation frequencies exceeding 1 Hz.
Structured PICO
PPopulationClosely appositioned cylindrical myocardial preparations from the ferret in vitro (n=8 pairs)
IInterventionIncreasing the resistance of the extracellular space to create a longitudinal extracellular potential difference >30-60 mV
OOutcomeEphaptic (non-synaptic) impulse transmissionsurrogate
Ephaptic interaction between myocardial cells can occur under specific conditions of increased extracellular resistance, which may be relevant to the genesis of arrhythmias.