Fehmi Keçe

Chapter 2 30 2.2 Point-by-Point radiofrequency ablation After evidence that the pulmonary veins (PV) are the primary source of AF (10, 11), non- cooled radiofrequency ablation of ectopic beats from the PVs has been introduced (12, 13). Due to the high incidence of PV stenosis, (14) ablation has evolved from segmental ablation of the PVs guided by a circular mapping catheter (4, 15, 16) to wide-area circumferential PV isolation (17). 2.2.1 Historical overview Catheter irrigation resulted in a lower risk for coagulum formation allowing for higher energy transfer with larger and deeper lesions (18, 19) and improved outcome (20), with a current AF free survival of 46-94% at one-year follow-up (table 1a/b). The introduction of three-dimensional electro-anatomical mapping systems (CARTO, Biosense Webster Inc. Diamond Bar, California, USA and Ensite, Abbott, St. Paul, Minnesota, USA) and image- integration tools has been associated with improved efficacy (21-25). Contact-force (CF) measurement during ablation has been developed to improve lesion formation (Thermocool Smarttouch, Biosense and Tacticath, Abbott; Figure 1) with a reported one-year AF free survival between 52-94% (table 1a/1b). There are conflicting reports whether CF improves ablation outcome (table 1b) (26, 27), suggesting that CF parameters need to be validated (26). Data from a recent meta-analysis suggest that ablation guided by CF is associated with improved median outcome at 12-months follow-up (28). Recent developments focus on improved near-field resolution by combining recordings from large-tip electrodes with recordings from micro-electrodes (QDOT-micro technology for Biosense Webster Inc.). 2.2.2 Procedure time Procedural length has been associated with higher complication rates (29). Although radiation exposure can be reduced with 3D-mapping systems (24), point-by-point ablation often requires longer procedure times compared to single-shot techniques. Reported mean procedural time range between 101-284 minutes (table 1a/1b). Contact-force has been associated with reduced procedure, ablation and fluoroscopy times (28) and high-power-short-duration radiofrequency (RF) applications to further reduce procedure time are currently under investigation (30-32). Fluoroscopy time for RFCA, however approaches to zero under increasing experience of 3D-mappings systems and intracardiac electrocardiography (33, 34).