[Tolerance to cardiotoxic effect of strophanthane K in experimental total heart block and electrocardiostimulation].

Tolerance to the cardiotoxic effect of strophanthin K was studied in narcotized dogs with experimental complete heart block (CHB) and ventricular electrostimulation. A threshold to the toxic arrhythmogenic effect of strophanthin K was significantly reduced as compared to that in the control group. As the electrocardiostimulation (ECS) frequency increased, the minimum arrhythmogenic dose of strophanthin K showed a growth, while not reaching a level for the sinus rhythm. It is concluded that the basic mechanisms of the arrhythmogenic effect of strophanthin K under the conditions studied are the trigger activity in dogs with ECS and the increased peacemaker's activity in dogs with CHB.