Patient
- 65-year-old man
- Reply DR pacemaker (Sorin) for sinus dysfunction
- SafeR algorithm
- programmed value for long PR 350 ms (AR 450 ms)
- episodes of switch to DDD for first degree AV block (AVB1) recorded in AIDA (memory of the device)
Tracing
- atrial pacing with ventricular sensing (AR)
- AR intervals between 367 and 406 ms (less than the programmed value)
- prolongation of the AR intervals (> 450 ms)
- after 6 consecutive cycles with AR interval > 450 ms, switch to DDD (vertical line)
- atrial and ventricular pacing
Comments
- the device switches to DDD when PR or AR intervals are longer than the programmed maximum programmable value during 6 consecutive cycles
- only the long PR (sensed atrial activity) interval is programmable
- the long AR value (paced atrial activity) = long PR + 100 ms
- The AVB I (first degree AV block) criterion can be programmed to: rest + exercise (the device may switch to DDD during rest and exercise phases) or to exercise only (the device may switch to DDD during exercise phase only)