Analysis of the preferable site and stability of rotational reentry: its role for the maintenance of atrial fibrillation.

It remains unclear whether AF is maintained by rotor. We evaluated the significance of rotor during atrial fibrillation (AF). Prevalence, location, and stability of rotational reentry (RR) in the left atrium were clarified by endocardial non-contact mapping in 66 AF patients. RR was classified into three categories: RR continued at stable site (Stable-RR), RR observed intermittently at the same site (Intermittent-RR), and RR observed at different locations (Different-RR). Catheter ablation was performed in a stepwise fashion (linear roof lesion and complex fractionated atrial electrogram ablation following pulmonary vein isolation) until AF termination and elucidated the consequence of radiofrequency lesion delivered within RR site on AF termination and recurrence. One hundred and nineteen RRs were observed. There were 54 patients with RR (RR Group) and 22 patients without RR (Non-RR Group). Prevalence of Different-RR (n = 81) was significantly higher than Stable-RR (n = 16, p < 0.001) and Intermittent-RR (n = 22, p < 0.001). The intervals involved in RR occupied only 22.4% of total activation time. There was no significant difference in the prevalence of AF termination nor AF/atrial tachycardia recurrence between RR and non-RR Groups (46 vs. 9 patients, p = 0.317, and 13 vs. 1 patients, p = 0.271) and between patients in whom radiofrequency lesion was involved in RR and those was not (24 vs. 22 patients, p = 0.210, and 6 vs. 7 patients, p = 0.506). In conclusion, most RRs were observed transiently and often shifted its locations. Radiofrequency lesion delivered within RR site did not correlate with AF termination nor recurrence, suggesting that RR is not a driving source during AF.

Slow Potential at the Entrance of the Slow Conduction Zone in the Reentry Circuit of a Verapamil-Sensitive Atrial Tachycardia Originating From the Atrioventricular Annulus.

BACKGROUND: Slow conduction zone in a verapamil-sensitive reentrant atrial tachycardia originating from atrioventricular annulus is composed of calcium channel-dependent tissue. We examined whether there was a slow potential (SP) at the entrance of the slow conduction zone. METHODS AND RESULTS: We first identified the pacing site from where manifest entrainment and orthodromic capture of the earliest atrial activation site were demonstrated in 40 atrioventricular annulus patients with atrioventricular annulus. Radiofrequency energy was then delivered 2 cm proximal to the earliest atrial activation site in the direction of entrainment pacing site and gradually advanced toward the earliest atrial activation site until atrial tachycardia termination to localize the entrance of the slow conduction zone. Electrogram characteristics were analyzed at successful and unsuccessful ablation sites. During sinus rhythm, SP was observed at all 40 successful sites, but was observed at only 12 unsuccessful sites (P<0.0001). During sinus rhythm, there was no significant difference in electrogram amplitude nor width of atrial electrogram between successful and unsuccessful sites (0.407±0.281 versus 0.487±0.447 mV [P=0.1989] and 37.0±9.2 versus 38.9±8.0 ms [P=0.1773]); however, SP amplitude and width at successful sites were significantly greater than those at unsuccessful sites (0.110±0.049 versus 0.025±0.046 mV [P<0.0001] and 38.8±13.4 versus 8.1±13.2 ms [P<0.0001]). During atrial tachycardia, SP amplitude was significantly attenuated (0.088±0.042 versus 0.110±0.049 mV, P<0.001) and SP width was significantly prolonged (47.8±14.1 versus 38.8±13.4 ms, P<0.0001) at successful sites. CONCLUSIONS: SP was observed during sinus rhythm at the entrance of the slow conduction zone; however, SP amplitude was attenuated and SP width was prolonged during atrial tachycardia, suggesting that SP reflects the characteristics of calcium channel-dependent tissue involved in atrioventricular annulus reentry circuit.

Prevalence and mechanism of rotor activation identified during atrial fibrillation by noncontact mapping: Lack of evidence for a role in the maintenance of atrial fibrillation.

BACKGROUND: It remains unclear whether atrial fibrillation (AF) is maintained by the rotor. OBJECTIVE: We evaluated the role of the rotor and examined its mechanism. METHODS: Among 75 patients with AF (60 paroxysmal, 15 persistent AF) who underwent 3-dimensional noncontact left atrial mapping during AF, we examined the prevalence and location of rotor activation and elucidated its mechanism. Catheter ablation was performed in a stepwise fashion (linear roof lesion and complex fractionated atrial electrogram ablation after pulmonary vein [PV) isolation) until AF termination. RESULTS: Rotor activation was observed in 11 patients (14.7%; 10 paroxysmal and 1 persistent AF) (tachycardia cycle length 160.0 ± 19.8 ms). Rotors were observed transiently (duration 6128 ± 9094 ms) during AF at the roof (n = 5), septum (n = 3), and ostium of the left superior PV (n = 3). Five rotors circulated in clockwise and 6 in counterclockwise directions. The length of the block line at the center of the rotor was 15.2 ± 6.9 mm. The electrograms at the block line showed low-amplitude multiple deflections (n = 7) or double potentials (n = 4), and the amplitudes during rotor activation were significantly lower than those during sinus rhythm (0.27 ± 0.18 mV vs 1.22 ± 0.92 mV; P < .01). No conduction disturbances were found during sinus rhythm, suggesting that the central line of block was formed functionally. AF was terminated by PV isolation alone without additional lesions in patients with rotors. CONCLUSION: Functionally formed rotor activation was observed during AF in a limited number of patients. These rotor activations may not be related to AF maintenance, but rather may reflect a transient organization of random propagation.