MVP and dropped P-waves

Tracing
N° 2
Manufacturer Medtronic Device PM Field MVP
Patient
  • 67-year-old man
  • Dual-chamber pacemaker (Medtronic) for complete atrioventricular block
  • DDD mode
Graph and trace

Tracing 2a: 12 lead ECG

  • DDD mode: atrial pacing and ventricular pacing
  • Programming of the MVP mode: atrial pacing not followed by a ventricular sensed  event (first dropped atrial activity)
  • On the following cycle, atrial pacing and ventricular pacing with a short AV delay (80 ms)
  • Identical sequence: atrial pacing not followed by a ventricular sensed  event, atrial pacing and ventricular pacing with a short AV delay
  • No ventricular sensed event in 2 of 4 preceding A-A intervals: automatic switch to DDD mode

 

Tracing 2b: EGM

  • Programming of the MVP mode
  • After a blocked atrial pacing, short AV delay (80 ms) on the following cycle
Comments
  • This tracing shows the specificities of the operation of the first version of the MVP mode in a patient with atrioventricular block
  • This algorithm tolerates the presence of intermittent dropped P-waves; a single dropped P wave does not induce switching to DDD
  • The short AV delay (80 ms) with safety ventricular pacing on the cycle following the dropped atrial activity is the signature feature of this mode
  • There cannot be two consecutive dropped atrial activities
  • There is a single criterion for switching to the DDD mode; the device automatically switches from AAI to DDD mode, when no ventricular sensed event occurs in 2 of 4 preceding A-A intervals
  • The maximal duration of the ventricular pause depends on the sinus rate and on the programmed lower rate limit (more or less equal to half the programmed minimal rate)