December 2018

Remote transmission with multiple atrial mode switch episodes

Claire O’Neill – Advanced Specialist Cardiac Physiologist
Manchester University NHS Trust


A remote transmission was received for a 61 year old female implanted with a dual chamber ICD in 2013 for Long QT associated with polymorphic VT and VF. The download revealed multiple atrial mode switch (AMS) episodes. One AMS episode is displayed in figure 1. The device settings are presented below:

Mode: DDDR
Base rate: 60bpm
Max sensor rate: 110bpm
Paced AV delay: 200ms, Sensed AV delay: 150ms
Ventricular intrinsic preference (VIP): On
PVARP: 275ms, PVAB: 60ms
PVC response: Off

Figure 1
AMS episode EGM received via remote download. Channel 1 shows the Atrial EGM, Channel 2 shows Ventricular EGM and channel 3 shows the marker channel.


What does the EGM show?

  • Far field R wave oversensing

  • Pacemaker mediated tachycardia (PMT)

  • Repetitive non-reentrant VA synchrony (RNRVAS)

  • Loss of atrial capture due to high atrial threshold

  • Atrial arrhythmia AT/AF