Fehmi Keçe

Chapter 7 146 7.2 Methods 7.2.1 Study Population Consecutive patients undergoing a first AF ablation with cryoballoon at the Leiden University Medical Center between 2014 and 2017 were included. Patient characteristics and procedural data were collected using the departmental Cardiology Information System (EPD-Vision). The ablation files were extracted from the ablation console to derive biophysical parameters of each cryo-application. This retrospective study was approved by the institutional ethical review board. 7.2.2 Ablation procedure All anti-arrhythmic drugs (except amiodaron) were discontinued for at least 3 days before ablation. Ablation was performed with a 28-mm second-generation cryoballoon (Arctic Front Advance, Medtronic Inc., Minneapolis, MN, USA). The 23-mm balloon was only used in PVs with a diameter <20 mm in which PV isolation could not be achieved with the 28mm balloon. A single cryo-application was performed per PV. The ablation duration was set to 240 s except for the right superior PV in which the application duration was decreased to 180 s to prevent phrenic nerve palsy(2, 8). During ablation, time-to-isolation was measured, defined as the time from start of the application until disappearance of the PV potentials recorded from a 20 mm intraluminal circumferential mapping catheter with 8 electrodes (Achieve, Medtronic, Minneapolis, MN). The cryo-application was aborted and the balloon repositioned if isolation was not achieved within 90 seconds. After a waiting period of 30-minutes, PV isolation was re-assessed. If a given PV was reconnected, additional cryo-applications were performed until PVI was achieved. In the presence of PVI, dormant PV conduction was tested during adenosine infusion. An increasing dose of adenosine (18 up to 30mg i.v.) was administered until >1 sinus beat with blocked AV-conduction was observed. In case of dormant conduction, additional applications were performed, with a maximum of 2. Early reconnection was defined as acute reconnection directly after the application or reconnection or dormant conduction tested with adenosine after a waiting-period of 30 minutes. For the prevention of phrenic nerve palsy, high-output pacing (20mA/2ms) of the phrenic nerve from the superior caval vein was performed with manual palpation of the diaphragmatic movement to confirm and control capture. Endoluminal esophageal temperature was monitored with a nasal temperature probe (Sensitherm, St. Jude Medical, Saint Paul, MN, USA). Applications were terminated with a ‘double stop technique’ if the temperature of the esophagus reached <18