AV dissociation
- Default:
- slowing of SA node allows subsidiary pacemaker (eg, AV junction) to take over
- 篡奪 Usurpation:
- acceleration of subsidiary pacemaker
- (eg, AV junctional tach, VT)
- 3° AV block:
- atrial pacemaker unable to capture ventricles, subsidiary pacemaker emerges;
- distinguish from isorhythmic dissociation (A ≈ V rate, some P waves nonconducting)