Looked Like Pacemaker Malfunction But Not

Vignette: A patient s/p pacemaker implantation was being monitored in the unit. The primary RN was notified of this event? Is this a pacemaker malfunction?

Image 1 - ECG case

AF with failure to capture and intermittent undersening

A 75 yo with h/o DM, HTN, s/p PPM admitted for stroke. What is wrong in the ECG?

Figure 1 - ECG case

Atrial fibrillation, intermittent failure to capture (non-capture), rate-dependent RBBB

Atrial fibrillation, intermittent failure to capture (non-capture), rate-dependent RBBB

#639

AF with slow ventricular response in a patient with VVI pacemaker with intermittent loss of capture and intermittent undersensing

Interpretation courtesy of Dr. Raed Abu Sham'a:

The underlying rhythm is AF [no clear P waves]. There are QRSs of 4 different morphologies. The ventricular rhythm is irregular which excludes underlying CAVB in AF patient. There is at irregular pacing  spikes. If you have completely irregular pacing spikes like this, then there is a combined problem!!! There is no capture after the spikes which indicates non-capture problem and the pacing spikes fall randomly that  indicate undersensing. Furthermore, they are irregular which indicates intermittent undersensing. Example of this is QRS 1 and 2 are undersensed and QRS 3 is sensed and the following spike is delayed to the lower pacing limit. There are two paced beats with capture [8, 12]. Here are all beats: QRS 1=US, 2=US, 3=S, 4=S, 5=S, 6=US, 7=S, 8=P, 9=S, 10=S, 11=S, 12=P, 13=S, 14=S, 15=S. Interestingly after the two paced beats there are two beats [9 and 13] of the same morphology and coupling intervals. These are called bundle branch reentrant beats. In conclusion: AF with slow ventricular response in a patient with VVI pacemaker [temporary or permanent] with intermittent loss of capture and intermittent undersensing.

#81

AAISafeR mode

Here, 3 paced atrial events were not followed by a ventricular event (AAIR mode). After that the machine switched to DDD mode. Also note the lengthening of the PRI interval in the middle. Seems to have a 3:2 AV Wenckebach cycle.

AAISafeR mode operates in the AAIR and switches to DDDR mode when criteria are met.

AVB Criteria 2 – if 3 of 12 sensed or paced atrial events are not followed by ventricular event

Reference:

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

#64

AAISafeR Mode

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

Image 1