Ventricular undersensing

Tracing
N° 1
Manufacturer Boston Scientific Device PM Field Sensing
Patient
  • 80-year-old man
  • Vitalio pacemaker (Boston Scientific) for sinus dysfunction
  • Episodes classified as Rythmiq in the device memory
Graph and trace
  • Ventricular undersensing
  • Ventricular backup pacing as a result of this undersensing
  • Second ventricular backup pacing
  • Ventricular undersensing and ventricular backup pacing
  • Switch to DDD mode (RYTHMIQ)
Comments
  • This tracing illustrates a case of ventricular undersensing revealed by the presence of a RYTHMIQ switch
  • Ventricular undersensing is followed by backup pacing and switch to DDD mode
  • A good quality ventricular sensing, atrial sensing and atrial pacing is required for the RYTHMIQ algorithm to work properly
  • Recording an EGM in case of switch to DDD allows the diagnosis of even intermittent dysfunctions
  • Traditionally, unlike ICDs, pacemakers functioned with a fixed and stable sensitivity throughout the cardiac cycle
  • Modern pacemakers allow the programming of an ICD-like adaptive sensitivity (variable sensitivity levels according to the amplitude of the R wave or the sensed P wave with progressive increase in sensitivity during the cardiac cycle)
  • In Boston ScientificTM pacemakers, the 2 options are available: fixed sensitivity or adaptive sensitivity (automatic gain control, AGC)
  • The type of sensing method used (AGC or Fixed) must be the same for both leads
  • Atrial and ventricular sensitivity values can be programmed independently
  • If sensing is programmed on AGC, the nominal sensitivity value is 0.6 mV for the ventricle and 0.25 mV for the atrium
Other articles that may be of interest to you
PR Logic and Wavelet
EGM recordings