Recording pacemakers memory size-what should be recorded

A modified form of electrogram recording element was used in conjunction with an implanted anti-tachycardiac pacemaker employing a telemetry link. This permitted long term monitoring of the intra-cardiac electrogram signal during a series of mode switching operations carried out by the implanted device. The basic instrument included a 16 second circular buffer continuously recording the electrogram and pressure waveforms by overwriting the oldest data. On detection of an arrhythmia a portion of each waveform just before and after the event would be 'frozen' for subsequent studies. In the prototype system an 8192 (8 k) byte buffer was used. The electrogram was sampled at 400 samples per second and the pressure signal at 100 samples per second, allowing just over 16 seconds of each event to be stored. A 128 k byte static RAM module was used to implement the circular buffer and for storing recording wave forms. A total of 16 events could be retained in the memory at any time. A further 2 k bytes of static RAM was available for use by the programme and for the storage of statistical data.