Figure 1:
ECG tracings registered during Holter monitoring before ablation. A: A pause of 12.9 seconds in duration caused by paroxysmal AV block during AF. B: Fast ventricular response during AF, confirming the absence of structural conduction impairment. C: AV block developing during night hours simultaneously with SR deceleration most likely resulting from both sinus and AV node suppression by the increased vagal tone.