Catheter settings and left atrial mapping
Electrophysiological studies and catheter ablation were performed under general anesthesia using intravenous propofol at 5–10 ml as a bolus injection followed by 0.5 ml/kg/hr as a maintenance dose. A ventilator (HAMILTON C-1®; Hamilton Medical, Bonaduz, Switzerland) in synchronized intermittent mandatory ventilation mode with a respiratory rate of 12 breaths per min and tidal volume of 400 or 500 ml was used together with a supraglottic airway device (i-gel®; Intersurgical Limited, Berkshire, UK). An esophageal temperature probe (SensiTherm®; Abbott, St. Paul MN, USA) was inserted to monitor esophageal temperature during RFA at the left atrial posterior wall.
A 6-Fr decapolar electrode was inserted into the coronary sinus, while a second 6-Fr decapolar electrode was placed in the right atrium. Following a transseptal puncture at the fossa ovalis, one steerable long sheath (Agilis® M curve; Abbott) was introduced into the LA using a transseptal puncture technique.
Mapping in the left atrium and 4 PVs was then performed using RHYTHMIA® (Boston Scientific) under right atrial pacing rhythm (100 ppm) using the small basket catheter (Orion®; Boston Scientific) via the steerable long sheath. Criteria used for beat acceptance included stable cycle length, stable timing difference between two reference electrodes placed in the coronary sinus, respiratory gating, stable catheter location, and stable catheter signal compared to adjacent points.