Phrenic Nerve Limitation During Epicardial Catheter Ablation of Ventricular Tachycardia.

OBJECTIVES

This study sought to investigate the incidence of phrenic nerve (PN) limitation and the utility of displacing the PN with a balloon.

BACKGROUND

The PN can limit the epicardial ablation of ventricular tachycardia (VT).

METHODS

From 2010 to 2017, 363 patients undergoing VT epicardial ablation at a single center were studied. Before the ablation, we used high output (20-mA) pacing maneuvers to verify the course of the PN. When we observed its capture, we used 1 of 3 different approaches to protect it: 1) non-balloon strategy (nerve-sparing ablation); 2) PN displacement with a small balloon (6 mm × 20 mm); or 3) PN displacement with a large balloon (20 mm × 45 mm).

RESULTS

PN capture occurred in 25 patients (7%) at the target ablation site. The most common cause was myocarditis (12 patients [48%]), and the incidence of the PN limitation was significantly higher in myocarditis than in other causes (19% vs. 4%, respectively; p = 0.0002). PN displacement was attempted in 7 patients by using large balloons and in 6 patients with small balloons, resulting in successful PN displacements and complete late potential (LP) abolition in 6 patients (86%) and 3 patients (50%), respectively. Among the 12 patients in whom the non-balloon strategy was used, only 1 patient (8%) achieved LP abolition (compared with the large balloon group; p = 0.002), whereas 3 patients experienced PN paralysis.

CONCLUSIONS

The PN limited the epicardial ablation in 7% of patients. Because nerve-sparing ablations often resulted in PN injuries, a possible solution could be to displace the PN with a large balloon, leading to a safer procedure and completion of LP abolition.