Floating Potential and Far-Field Left Atrial Appendage Signals During Atrial Fibrillation Ablation

Atrial fibrillation ablations are often like exploring a new forest; there are interesting findings unique to every patient and it is “what keeps you coming back.”  This is an electrogram recorded during an ablation after completing a left atrial pulmonary venous antrum isolation and assessing the left superior pulmonary vein for entrance/exit block. On first exam, it looks as if some work needs to be done but on closer inspection there is evidence of a “floating potential” and far-field sensing of atrial appendage activity.  The longer cycle length electrogram (~3100msec) is a pulmonary vein potential that is firing regularly but not conducting out to the left atrium (exit block).  In addition, the shorter cycle length (~1000msec) is a slightly lower frequency left atrial appendage signal that is often recorded from the proximate left superior pulmonary vein.  I get the “floating potentials” less than 10-20% of cases but it is a welcome finding.

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