[Investigation of anomalous growth of heart refractoriness during tachycardia].

Action potential (AP) characteristics during anomalous growth of refractoriness (R) in rabbit atrium were investigated. Anomalous growth of R arises under the stimulation frequency more than 4-5 s-1. Anomalous R growth is accompanied by AP duration, amplitude and upstroke velocity decrease. These results are in a good agreement with the theoretical model (Pertsov et al., 1981), showing that anomalous R growth can be caused by a decrease of safety factor in propagation of the excitation wave.