Atrial refractory period

Post-ventricular atrial blanking

  • any ventricular pacing triggers a programmable atrial blanking (nominal value 150 ms)
  • any ventricular sensing triggers an atrial blanking (nominal value 100 ms)

Window of Atrial Rate Acceleration Detection (WARAD)

The device monitors atrial events prematurity beat after beat, and is able to label each ventricular cycle as «normal» or «suspicious». The WARAD is a dynamic atrial refractory period that is automatically triggered after every atrial event (paced or sensed).

  • available in all dual chamber devices
  • objective: discriminate atrial arrhythmia from sinus tachycardia
  • on the marker chains, any atrial event sensed inside the WARAD is marked: Ar
  • any atrial event detected in the WARAD triggers a new WARAD
  • non programmable: the duration of the WARAD period is automatically calculated


The calculation of the WARAD is based on the preceding PP interval:

  • 75 % of the current PP interval, if it is less than 750 ms
  • 62.5% of the current PP interval, if it exceeds 750 ms (80 bpm)


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