BOSTON
Leads:



Max AVD
: BOS 400 ms, SJM 450 ms, MVP infinity
Sensed AV offset / reverse hysteresis - decrease AVD - increase
refractory sensing - pace with a shorter AVD
AV search hysteresis: prolong by 30 msecs every 36 beats (changeable
parameters)

CONFIENT
AVSH and Dynamic AVD up to 400 ms
AVSH search interval 32-1024 cycles and AV increase 10-100% (max 400
ms)
Conditions for VT underdetection:
    DDR pacing
    VT rate > Pacing rate - AVD
    Stable VT occurs while AP above LRL (rate smoothing or sensor driven)

RYTHMIK
RYTHMIQ™ stage of AAI(R) with VVI backup:
The device provides AAI(R) at the LRL and/or sensor indicated rate
according to the normal brady DDD(R) mode.
The device provides backup VVI pacing at a rate of 15 ppm slower than
the LRL. The backup VVI pacing rate is limited to no slower than 30 ppm
and no faster than 60 ppm.  When there is good conduction, ventricular
pacing does not occur as the VVI backup mode runs in the background at
a reduced LRL.
The device monitors for loss of AV synchrony.  If 3 slow ventricular beats
are detected in a window of 11 beats, then the device automatically
switches to DDD(R) mode.  A slow beat for RYTHMIQ™ is defined as a
ventricular pace or ventricular sensed event that is at least 150 ms slower
than the AAI(R) pacing rate.”1    The 150 ms value is used to allow for
normal variations between cardiac cycles.
INGENIO™ records a RYTHMIQ Episode along with 20 seconds of electrogram data when RYTHMIQ
detects loss of AV synchrony.  .  When the DDD(R) stage of RYTHMIQ is active, the RYTHMIQ episode
is identified as “in progress”.”

If AV Search+ remains in AV hysteresis for at least 25 cardiac cycles, and less than 2 of the last 10
cycles are ventricular paced, then the device automatically switches the pacing mode back to AAI (R)
with VVI backup.

RYTHMIQ is designed to minimize unnecessary pacing without clinically significant pauses

RYTHMIQ operates like two pacemakers running concurrently—one in AAI(R) and one in VVI

RYTHMIQ does not require dropped ventricular beats to switch to DDD(R) pacing