AAISafeR Mode

This patient had a pacemaker and during routine monitoring this was seen.

Image 1

Is this pacemaker malfunction?

Image 2

The 3 arrows are atrial paced (AP) beats not followed by ventricular beat. The 2 AP’s (in between) were conducted. After these events, AV pacing resumed. This machine is working well. It is in AAISafeR mode.

According to a Cardiac Pacing book, an AAISafeR mode operates in the AAIR and switches to DDDR mode when criteria are met. These are:

AVB Criteria I – if at least seven intervals between AP or sensed events and ventricular sennsed exceed a predefined limit (programmable between 350-450 ms)

AVB Criteria 2 – if 3 of 12 sensed or paced atrial events are not followed by ventricular event (which seemed to be this case)

AVB Criteria 3 – 2 consecutive atrial events without consecutive venticular sensed events.

Reference:

Ellenbogen K et al. 2011Clinical Cardiac Pacing, Defibrillation and Resynchronization Therapy 4ed. Elsevier PA