Flexcath

The procedure was performed under conscious sedation with propofol and analgesia with fentanyl as required.
A quadripolar catheter (Dynamic XT^TM Boston Scientific, Marlborough, MA, USA) was used to confirm continuity of the phrenic nerve by pacing in the superior vena cava and continuous abdominal palpation during ablation of the right sided PVs (RPVs). Transseptal puncture was performed guided by intracardiac echocardiography. The cryoballoon was advanced to the LA via a steerable transseptal sheath (Flexcath ^®Medtronic, Minneapolis, MN, USA). The 28 mm cryoballoon was used in all patients. A multipolar mapping catheter (Achieve^TM Mapping Catheter, Medtronic, Minneapolis, MN, USA) was introduced for mapping the PV potentials. The degree of PV occlusion was evaluated by contrast injection after balloon inflation and placement and verified by PV angiography in the initial freezing period. Ablation was performed adherent to a 2*240 s freeze per vein protocol. Adhering to our center specific cryoballoon ablation protocol, the left superior pulmonary vein (LSPV) was isolated initially, followed by the left inferior pulmonary vein (LIPV), the right superior pulmonary vein (RSPV) and the right inferior pulmonary vein (RIPV), respectively. Persistent PVI (entrance and exit block) was confirmed after a waiting period of 20 min.

Briefly, a single trans-septal puncture is performed using a standard long sheath (Lamp, St. Jude Medical, St. Paul, MN, USA), guided by intracardiac echo (ViewFlex, St. Jude Medical) with the patient under conscious sedation and under infusion of unfractionated heparin aiming at an activated clotting time (ACT) of 250–300. The transeptal sheath is exchanged over a guidewire for a 15F deflectable introducer (Flexcath, Medtronic, Minneapolis, MN, USA), and a CB2 (Arctic Front Advance, Medtronic) is introduced, together with an inner circular mapping catheter (Achieve, Medtronic), into the antrum of each PV. All procedures were performed under the guidance of a three-dimensional reconstruction of the left atrium and the pulmonary veins, extracted from a cardiac CT or MRI scan, and using an esophageal temperature probe with multiple thermocouples and adjustments to the balloon position. Cryoenergy delivery was stopped in case of temperature drop below 26 °C. The right phrenic nerve was monitored with palpation and fluoroscopy during pacing. PV isolation was defined by the persistent elimination or dissociation of PV potentials, visualized by the circular mapping catheter (Achieve catheter). Time-to-effect (TTE) was defined as the time to PV isolation during ablation.

A transseptal puncture was performed to gain access to the left atrium, and a 15-Fr deflectable sheath (FlexCath, Medtronic) was advanced through the left atrium. A circular mapping catheter (Achieve; Medtronic) was used to record pulmonary vein potentials. Cryoenergy was delivered using a 28- or 23-mm balloon (second-generation Arctic Front Advance, Medtronic). The cryoballoon ablation procedure generally conformed to the practice guidelines for cryoballoon ablation in AF, and detailed approaches and dosing regimens, such as cryoenergy delivery time, fluoroscopic or intracardiac echocardiographic guidance for balloon positioning and occlusion, use of general anesthesia, and post-ablation testing, were applied at the operator's discretion (7 (link)).
After PVI, CTI ablation was performed in all patients with a typical atrial flutter. CTI ablation was not indicated in patients without documented or induced typical atrial flutter. When indicated, a linear lesion was created along the CTI image using a radiofrequency catheter under fluoroscopic guidance. The radiofrequency energy was set between 25 to 40 W during ablation, and an open-irrigated catheter was used. The choice of ablation catheter and settings were based on the operator's discretion. The CTI ablation was considered successful when a bidirectional block was demonstrated using differential pacing.

The CBA procedure has been previously described in detail [22 (link), 23 (link)]. Each center utilized its own standard-of-care practices and approaches during the cryoablation procedure. In general, subjects were treated under general anesthesia or conscious sedation. A transseptal needle puncture for left atrial access was immediately followed by a heparin bolus delivery, and the subsequent heparin delivery was administered while monitoring the activated clotting time. Most often, a purpose-built dedicated delivery sheath (FlexCath, Medtronic, Inc.) was used to advance the balloon catheter and guidewire assembly during the ablation procedure. CBA procedures were performed with a 23 mm and/or 28 mm cryoballoon, which was delivered by an over-the-wire method into the left atrium. The number of freeze applications and the length of individual freezes were determined by the hospital standard-of-care usage. In addition, postablation testing methods were left to the discretion of the physician operator; however, acute PVI was the intraprocedural efficacy endpoint, which was consistently defined as electrical conduction isolation confirmed by bidirectional block. In general, acute PVI was assessed using the dedicated balloon inner-lumen diagnostic mapping catheter (Achieve mapping catheter, Medtronic, Inc.) and/or a lasso style circular diagnostic mapping catheter.

Two electrophysiologists (MS and JvO) with extensive experience in cryoballoon ablation performed the procedures. All patients were on oral vitamin-K antagonists with the international normalised ratio between 2.5 and 3.5. Vitamin K antagonists were continued during the procedure [14 ]. All procedures were performed under general anaesthesia and arterial blood pressure was continuously monitored. Venous access was obtained from the right and left femoral vein. A diagnostic catheter (EP XT CS 4p, BARD Medical Inc., GA, USA) was positioned in the coronary sinus for stimulation of the LA. The LA was accessed by a transseptal puncture with a Brockenbrough needle monitored by intracardiac echocardiography (St. Jude Medical, MN, USA), first with a SL-O sheath (St. Jude Medical, MN, USA), changed over a 0.32 F wire to a steerable 12 F sheath (Flexcath, Medtronic Inc., MN, USA). During the procedure, heparin was given to achieve an activated clotting time of >350 s. The use of a 23 or 28 mm balloon was based on the PV diameters.

A 15‐Fr steerable sheath (FlexCath, Medtronic, Minneapolis, Minnesota) was advanced through the transseptal puncture. Then, a CB‐2 (Arctic Front Advance, Medtronic) was introduced into the sheath, inflated, and advanced to the ostium of each PV. The PV occlusion was assessed by venous angiography. Optimal vessel occlusion was achieved when selective contrast injection showed total contrast retention without backflow to the atrium. After the occlusion was documented, ablation was performed with at least two applications per vein, each for 150 to 180 seconds. The PV activity was recorded using Circular Achieve Catheter (Achieve, Medtronic) at a proximal site in the ostium prior to ablation in each vein. During the ablation of right PVs, a quadripolar catheter was inserted in the superior vena cava to monitor phrenic nerve palsy (PNP) by pacing the right phrenic nerve with a 1500‐ms cycle and a 20‐mA output. The freezing cycle was terminated immediately after a loss of capture, or the strength of right hemidiaphragmatic contractions was attenuated. No any additional RF ablations were applied during or after cryoablation were included. The Achieve Catheter was reintroduced and the bidirectional block was checked with a waiting time of 20 minutes after the last application. After isolation, if the AF did not convert to SR, external ECv was performed.

A 15-Fr steerable sheath (FlexCath, Medtronic, Minneapolis, MN, USA) was advanced through the transseptal puncture. Then, a second-generation 28 mm-cryoballoon (Arctic Front Advance, Medtronic) was introduced into the sheath, inflated, and advanced to the ostium of each PV. The PV occlusion was assessed by venous angiography. Optimal vessel occlusion was achieved when selective contrast injection showed total contrast retention without backflow to the atrium. After the occlusion was documented, ablation was performed with at least two applications per vein, each for 150–180 s. The PV activity was recorded using Circular Achieve Catheter (Achieve, Medtronic) at a proximal site in the ostium prior to ablation in each vein. During the ablation of right PVs, a quadripolar catheter was inserted in the superior vena cava to monitor phrenic nerve palsy (PNP) by pacing the right phrenic nerve with a 1500-ms cycle and a 20-mA output. The freezing cycle was terminated immediately after a loss of capture, or the strength of right hemidiaphragmatic contractions was attenuated. No any additional RF ablations were applied during or after cryoablation were included. The Achieve Catheter was reintroduced, and the bidirectional block was checked with a waiting time of 20 min after the last application. After isolation, if the AF did not convert to SR, external ECv was performed.