User Manual

Programming at implant:
It is not advisable to program the Smoothing function before implantation, since the
pacemaker may detect noise and pace at a rate higher than the programmed basic rate.
Recommendation:
Concomitant use of the Hysteresis function is highly advisable to avoid triggering of pacing for
slight variations in the patient’s spontaneous cycle (unless one of the AA prevention functions
is activated, for the DR model only).
Protecting the ventricles against AA: Mode switching
The Mode switching function is designed to avoid prolonged ventricular pacing at a high rate
for the entire duration of sustained atrial arrhythmia, by conversion to DDI(R) mode.
Operation:
1. Arrhythmia is identified by detection of abrupt acceleration of atrial rhythm. During the
phase of identification of an atrial arrhythmia, the ventricular pacing rate cannot exceed
120 ppm (or the maximum rate if the latter is lower) unless the patient has an exercise
induced SVT (rates above 120 ppm can be reached). The AV delay is 30 ms following
atrial sensing and 110 ms (or the exercise AV delay if the latter is lower) following atrial
pacing.
2. When atrial arrhythmia is confirmed, the pacemaker converts to DDI(R) mode at a pacing
rate that decreases gradually until it reaches the sensor-driven rate or the basic rate or
the rest rate.
3. As soon as the arrhythmia ceases, the pacing rate is gradually increased up to the atrial
rate (or sensor-driven rate). The pacemaker then converts to DDD mode: the atrium and
ventricle are resynchronized.
Limitation:
Mode switching occurs only if atrial arrhythmia is greater than 120 ppm.
NOTE: In SafeR mode, the Pause is automatically and temporarily set to 2 seconds in the
event of atrial arrhythmia (as-shipped value is 3 seconds).
If a retrograde P wave falls within the refractory period, the pacemaker does not start an AV
delay, thus preventing induction of PMT.
OPTIMIZING OPERATION
The following table details which functions are available according to the pacemaker model:
Features DR model SR model
Automatic implant detection x x*
Autosensing x x*
Ventricular Autothreshold x x*
Atrial Autothreshold x
PMT protection x
Lead Polarity Switch x x*
*except if the SR is implanted for the atrium
15.6.6.
15.7.
15. FUNCTIONS AND PARAMETERS
46 ALIZEA – UA10414A