Fehmi Keçe

Chapter 2 40 2.4 Balloon-based devices Several balloon-based devices have been developed for PVI (Figure 2), including the cryoballoon, the hotballoon, the endoscopic laserballoon and the high-intensity focused ultrasound balloon. The latter is no longer available (for safety reasons) and will not be discussed in this review. A potential limitation of these devices is the more distal PVI compared to point-by-point isolation (65). However, over the last decade, balloon-based devices have undergone important technical improvements. 2.4.1 Cryoballoon 2.4.1.1 Historical overview First animal studies with cryoballoon ablation were published in 2005 (66, 67). A double- lumen balloon is cooled by expansion of NO 2 (66). The second-generation cryoballoon (Arctic Front Advance, Medtronic Inc., Minneapolis, MN, USA) have an increased gas flow, improved temperature uniformity and a more proximal cooling of the balloon with more internal injection ports compared to the first-generation (68). The broader cooling zone, together with easier positioning of the balloon with the second-generation steerable sheath (Flexcath Advance) and real-time assessment of PV isolation with the intraluminal spiral catheter (Achieve) has resulted in enhanced lesion durability and more antral ablation (69, 70). Recent studies reported success rates (off AAD) of 76-86% after 1-2 years for the first and second generation cryoballoon (71-78) (table 2). Freedom of AF off drugs was reported in 48-74% of patients for the first-generation cryoballoon and in 65-83% for the second- generation cryoballoon at 1 year follow-up. In a retrospective study, comparing the two balloons no significant differences in outcome was observed (78 vs. 83% at 1 year follow up) (79). The third-generation cryoballoon with a shorter tip to facilitate better PV-signal recordings is still being developed. 2.4.2 Procedure time With the development of the second-generation cryoballoon, the ablation protocol has been adapted with reduced cryo-application times (180s instead of 2 times 300s) (79, 80). Recent studies evaluating shorter applications times based on the time-to-isolation showed a similar efficacy at 1 year follow-up (72-77, 81).