Catheter ablation induced phrenic nerve palsy by pulsed field ablation—completely impossible? A case series

BACKGROUND: Pulsed field ablation (PFA) is a new feasible and safe method for the ablative treatment of cardiac arrhythmias, such as atrial fibrillation (AF). Through the use of electric fields, it causes pore-like openings in the cell’s wall, leading to cell death. The most appealing characteristic of this new technique is its selectivity for cardiomyocytes and consequently its low risk of collateral damage to extracardiac tissues. We present three cases of a PFA-induced transient phrenic nerve (PN) injury documented during pulmonary vein isolation (PVI). CASE SUMMARIES: Three patients aged 55–81 years underwent PFA for symptomatic AF. Cases 1 and 3 were affected by paroxysmal AF without evidence of structural heart disease. Case 2 had persistent AF and ischaemic cardiomyopathy with preserved ejection fraction. We observed a transient right hemidiaphragm palsy during the delivery of impulses in the right superior pulmonary vein (Cases 1 and 2) and in the right inferior pulmonary vein (Case 3). The palsy lasted <1 min and was followed by spontaneous full recovery in all cases. DISCUSSION: Transient PN dysfunction can be observed following PFA in AF ablation. According to our initial experience, a full recovery of the PN function can be expected within seconds. We hypothesize a hyperpolarization of neuronal cells or a depletion of acetylcholine in the motoric endplate to explain this event. Further studies are required to understand the exact pathophysiological mechanism.