Influence of temperature on the atrioventricular conduction time for spontaneous and imposed rhythms

In the present work data are obtained about the changes in the atrioventricular conduction time under the effect of two parameters: temperature and frequency of the sinus node. The experiments are carried out on preparations from the right atrium of rabbit heart. Temperature changes are obtained by regulation of the temperature of the nutrient medium in the 23--36 degrees C range. The excitation frequency of the sinus node was changed by imposition of artificial (external) rhythms. Data are obtained about the presence of frequency- and temperature-dependent components of the atrioventricular (AV) delay. Upon cooling the preparation the influence of the temperature factor is predominant and parallel with this the capacity for assimilating a higher imposed rhythm decreases. Considerations are expressed about the behaviour of the AV-conduction system at different temperatures under conditions of saccadic changes in the imposed rhythm.