In 1998, Haïssaguerre et al.
14 noted frequent action potentials in the PVs and reported that these potentials trigger the onset of PAF. Since then, electrical isolation of PV (PV isolation) has been performed as a radiofrequency (RF) ablation technique for PAF with the hope of preventing the conductionof pulmonary vein activation in the left atrium where it may serve as a trigger of PAF. The initial PV isolation was a focal or segmental isolation technique which isolates each of four PVs using the potentials traveling from the PVs to the left atrium as a guide. In 2001, Pappone et al.
15 reported circumferential PV isolation, which simultaneously isolates all four PVs (left superior, left inferior, right superior, right inferior). This approach had been made feasible by the use of a 3D-mapping system enabling anatomical RF ablation as well as confirmation of whether electrical isolation has been successfully completed. It was reported that this new approach provided more favorable results than focal isolation.
16 Although RF ablation had previously been indicated for PAF only, it has also been performed in patients with persistent AF since 2003. As for RF ablation for persistent AF, linear RF ablation in the left atrium was considered necessary to block conduction within the left atrium in order to preventLA reentry. Linear RF ablation of the following sites was therefore performed in addition to PV isolation
17–19: the roof of the left atrium (from the superior wall of the orifice of the left superior PV to the superior wall of the orifice of the right superior PV), the region between the mitral annulus and the inferior wall of the orifice of the left inferior PV (mitral isthmus), the region between the mitral annulus and the inferior wall of the orifice of the right inferior PV, and the anterior and posterior mitral annulus. Around the same time, Nademanee et al.
20 reported, based on LA mapping during AF, that CFAE in the left atrium is a good indicator of RF ablation. Pappone et al. found, during circumferential PV isolation, a site where RF ablation had induced a decrease in blood pressure and caused atrioventricular block. They focused on the lower AF recurrence rate in these cases, judged that this site is the vagal nerve on the basis of its autonomic mechanism, analyzed the autonomic mechanism, and reported that, if the vagal nerve is blocked and isolated by RF ablation, the AF recurrence rate is lowered.
21 Later, Lemery et al. defined a site at which high-frequency, high-power stimulation provided during AF prolongs the R-R interval by ≥50%, increases blood pressure by ≥20 mmHg, and causes distress in anesthetized patients as ganglionated plexuses (GP), and reported that RF ablation of this site lowers the AF recurrence rate.
22 In light of the mechanism of AF onset, ablation strategies have shifted toward targeting AFs occurring in atrial muscles with more progressed remodeling, in other words, persisten
23 reported that segmental ablation alone rather than with additional linear ablation reduces complications originating from the left atrium (e.g., tachycardia) in the case of initial ablation for PAF patients with less progressed remodeling. Another report
24 indicated that not all CFAEs may be responsible for AF maintenance. Although CFAE is considered responsible for AF maintenance through autonomic innervation, it is also recorded in patients with no history of AF in whom AF was induced by electrical stimulation. As described above, no methodology of RF ablation for AF has yet been established, and ablation strategies may differ by institutions. Nonetheless, as RF ablation for AF is widely performed today, the differences in expertise and methodology between institutions appear to be reducing.