A method for determining the atrial effective refractory period in the unanesthetized dog

Extension to the unanesthetized dog with chronic A-V block of the method of determination of the atrial effective refractory period described in vitro by Dawes provides a useful model for the study in atria of potential antiarrhythmic agents. This model, which comes fairly close to physiological conditions, is capable of furnishing reproducible results which correlate well with those obtained by other techniques, as shown by a study of quinidine chosen as reference. It also makes possible long-term studies of the effects of prolonged administration of antiarrhythmic agents on atrial effective refractory period, under conditions close to those of therapeutic practice, and so is likely to have predictive value.