An Implantable Pulse Generator Indicating Asystole or Extreme Bradycardia

The design of a pacemaker which indicates the occurrence of significant bradyarrhythmia is described. Significant bradyarrhythmia is defined as either asystole for 6 seconds, bradycardia with three successive RR-intervals greater than 2 seconds each, or five or more RR-intervals of 2 seconds or more over a period of 25 seconds, but without three such intervals in succession. During bradyarrhythmia the generator initially stimulates at an interval of 2 seconds (30 per minute) and when the described criteria have been fullfilled the pacemaker automatically converts to a conventional ventricular inhibited pulse generator stimulating at a rate of 70 per minute.