Ablation of atrial fibrillation in humans using a balloon-based ablation system: identification of the site of phrenic nerve damage using pacing maneuvers and CARTO.

Injury of the phrenic nerve during pulmonary vein isolation for the treatment of atrial fibrillation is a well-recognized complication, especially when performing ostial ablations or using balloon-based technologies. This report describes the exact anatomical location of phrenic nerve injury during an attempt of right superior pulmonary vein isolation using a balloon that delivered high intensity focused ultrasound. Electroanatomical three-dimensional CARTO (Biosense Webster, Diamond Bar, CA, USA) mapping of the superior caval vein, the right and left atrium, as well as the right superior pulmonary vein was performed in conjunction with meticulous phrenic nerve pacing maneuvers before and after ablation and showed that the nerve was damaged at the level of the antero-inferior ostium of the right superior pulmonary vein. Diaphragmatic denervation occurred despite using an oversized balloon fluoroscopically placed at the atrial side of the pulmonary vein ostium.