User's Manual

US-ENGLISH – 61
Non-serious events due to the use of SafeR included: delay in
switching on 2nd degree AV block, inappropriate classification of a
PAC, disagreement between markers and recorded EGM, atrial pacing
above the maximum rate, recycling on an r-wave in a refractory period,
and disagreement in the statistics for switches to DDD. No patient
symptoms were associated with these events.
18.2. SAFER CLINICAL STUDY
SafeR mode in PARADYM RF is similar to that in Symphony.
The differences in SafeR mode between the two devices are:
─ To prevent long RR intervals during VT/VF, SafeR has no effect during
VT/VF therapy, electrophysiologic studies, and post-shock recovery.
─ The maximum acceptable AV delay for first degree AV block varies
as a function of pacing rate.
─ PARADYM RF requires a ventricular sensed event to atrial paced
event (RA) interval of at least 100 ms. Therefore, the device
lengthens the atrial escape interval so that it ends at least 102 ms
after the ventricular event.
─ During atrial fibrillation episode, pause criterion is fixed to 2s to
avoid long bradycardia episodes in switching to DDD mode.
Despite these differences, the data collected on Symphony devices are
applicable to PARADYM RF because the principles of SafeR operation
did not change. The criteria for switching from AAI to DDD (or vice
versa) did not change. The device’s method for evaluating the
presence of AV conduction did not change.
Methods: All patients were implanted with a Symphony Model 2550 dual-
chamber rate-responsive pacemaker with SafeR mode. A variety of
marketed atrial and ventricular pacing leads were used. The pacemaker
was programmed and interrogated via bi-directional telemetry using a Sorin
CRM dedicated programmer and a CPR3 programming head.
The study’s routine evaluation consisted of enrollment, pre-discharge
evaluation, and a scheduled follow-up visit at one month.