RESUMO
Background: Atypical left atrial flutter (AFL) may be macroreentrant or spatially localized. The relationship between the critical isthmus (CI) for localized reentry with sinus rhythm (SR) conduction slowing has not been systematically examined. Objective: To examine the correlation between CI sites for localized AFL (L-AFL) and deceleration zones (DZ) identified by isochronal late activation mapping (ILAM) during baseline rhythm. Methods: Patients with localized AFL who underwent high-density activation mapping of both SR and AFL were retrospectively analyzed. L-AFL was defined as reentry restricted to 2 wall segments of the left atrium. CI was defined by activation mapping and sites of successful termination during ablation. DZ, defined as >3 isochrones within 1 cm radius during baseline rhythm, were correlated to the locations of the CI. Results: Thirty-one consecutive patients that underwent detailed sinus rhythm and AFL high-density activation maps were analyzed at 3 centers. A mean 4060 ± 3275 and 6209 ± 8656 points were collected in ILAM and AFL activation maps, respectively. At least 1 DZ (1.7 ± 0.77) was identified in all patients. ILAM showed 3.27 ± 0.52 isochrones per DZ (168 ± 32 ms), and co-localized to CI sites at a distance of 6.7 ± 3 mm. A total of 34% ± 14% of the AFL cycle length was contained within 0.5 cm of the DZ. Conclusions: In patients with L-AFL, CI co-localized with DZ during baseline rhythm, suggesting that DZ mapping during SR may yield candidate targets for ablation as an adjunct to pulmonary vein isolation to prevent a subtype of AFL.
RESUMO
PURPOSE: Accessory pathway (AP) mapping is currently based on point-by-point mapping and identifying if a local electrogram's origin is atrial, pathway, or ventricular, which is time-consuming and prone to insufficient mapping. We sought to determine the feasibility of automated and high-density mapping to define AP location using open-window mapping (OWM), which does not rely on defining the electrogram's origin but simply detects the sharpest local signal at each point. METHODS: We enrolled 23 consecutive patients undergoing catheter ablation for atrioventricular reentrant tachycardia. High-density mapping was performed using OWM and ablation was performed. The successful site of ablation was determined by the loss of pathway function. RESULTS: OWM was 100% effective at identifying the successful site of ablation (average mapping time 7.3 ± 4.3 min.) Permanent AP elimination was achieved using a mean radiofrequency energy time of 18.5 ± 24.5 s/patient. Transiently successful ablations were 4.0 ± 1.8 mm from permanently successful sites and had lower contact force (5.1 ± 2.5 g vs. 11.7 ± 9.0 g; P = 0.041). Unsuccessful sites had similar contact force to permanently successful sites (12.2 ± 9.2 g vs. 11.7 ± 9.0 g; P = 0.856) but were 6.4 ± 2.0 mm away from successful sites. CONCLUSION: A novel technique of high-density, automated, and open-window mapping (OWM) effectively localizes APs without the need to differentiate the signal's site of origin. These findings suggest that OWM can be used to rapidly and successfully map and ablate APs. Both distances from the pathway and contact force were shown to be important for pathway ablation.