Key Wordsatrial fibrillation, cryoballoon ablation, pulmonary vein isolation, pulmonary vein distension.
IntroductionCryothermal energy has emerged as an alternative ablation energy that does not issue in the clot formation and excessive tissue damage that occur with radiofrequency (RF) energy-based catheter ablation. [1] Although cryothermal energy is a milder and safer form of energy than RF energy, pulmonary vein isolation (PVI) performed with a second-generation cryoballoon has been highly successful in cases of paroxysmal atrial fibrillation (AF) and comparable to PVI performed by point by point-based RF ablation [2]-[6] or even contact force (CF)-based RF ablation.[7], [8] Despite the efficacy of cryoballoon ablation (CBA), however, some patients suffer recurrence of the AF, due mainly to PV reconnections or to non-PV triggers.[9], [10] Thus far, the mechanisms explaining durable and non-durable lesion formation around the PV ostium by means of second-generation CBA have not been fully investigated. Because establishing good balloon surface-totissue contact is essential for successful CBA of AF, we investigated, by means of 3-dimensional (3D) geometric imaging, how the inflated balloon surface contacts the 4 PVs. We then characterized lesions created around the PV ostia by CBA and those created by CF-based ablation to clarify the mechanism responsible for the efficacy of CBA.
Material and Methods
Study PatientsThe study involved 112 consecutive patients treated for AF (symptomatic paroxysmal AF [n=88] or persistent AF [n=24]) at Nihon University Itabashi Hospital between September 2014 and December 2015. The patient series comprised 72 men and 40 women with a mean±SD age of 63.8±7.7 years and median duration of AF of 18 months (interquartile range, 6-48 months). Patients were blindly (but not randomly) assigned to 1 of 2 ablation procedures: PVI performed by means of second-generation CBA (CBA group, n=56) and PVI performed by means of CF-based RF catheter ablation (CF group, n=56). Written informed consent was obtained from all patients. All antiarrhythmic drugs were withdrawn for at least 5 half-lives prior to the procedure. Transesophageal and transthoracic echocardiography were performed 1 day before the ablation procedure with an ACUSON Sequoia C256 echocardiography system (Siemens Medical Solutions USA, Inc., Malvern, PA). LA diameter (LAD) and maximum LA volume (by the prolate ellipsoid method) were determined, and the left ventricular ejection fraction (LVEF) was determined by means of M-mode echocardiography (Teichholz method). Multi-slice computed tomography was performed with a 320-detector row, dynamic volume scanner (Aquilion ONE; Toshiba Medical Systems, Tokyo, Japan) in all patients for 3D reconstruction of the left atrium (LA) and PVs before ablation.
Electrophysiologic Study and AblationElectrophysiologic study was performed in all patients under conscious sedation achieved with dexmedetomidine and fentanyl.www.jafib.com Apr-May 2017| Volume 9| Issue 6Abstract Background: The mechanism ex...