Intracardiac Catheter Fibrillation Thresholds as a Function of the Duration of 60 Hz Current and Electrode Area

Fibrillation thresholds and their relationship to the duration of 60 Hz current flow, expressed as the number of 60 Hz cycles applied to the heart are described. Results are obtained for catheter surface areas ranging from 0.224 mm2 to 90 mm2. The investigation indicates that the current fibrillation thresholds are exponentially related to the number of 60 Hz cycles allowed to flow and the ratio between the rheobase level and a single cycle of 60 Hz is in excess of 100:1.