LAUSR

What is the central question of this study? Is the slowed conduction upon premature ventricular activations during clinical electrophysiological testing attributable to the prolonged activation latency, or increased impulse propagation time, or both? What is the main finding and its importance? Prolonged activation latency at the stimulation site is the critical determinant of conduction slowing and associated changes in the ventricular response intervals in premature beats initiated during phase 3 repolarization in perfused guinea‐pig heart. These relations are likely to have an effect on arrhythmia induction and termination independently of the presence of ventricular conduction defects or the proximity of the stimulation site to the re‐entrant circuit.