Propagation Mapping Wave Collision Correlates to the Site of Successful Ablation During Voltage Mapping in Atrioventricular Nodal Reentry Tachycardia

Abstract

Voltage mapping has been used previously for slow-pathway localization for atrioventricular nodal reentrant tachycardia (AVNRT) ablation. However, propagation mapping may be a technique to further improve the localization of the slow pathway. This retrospective study aimed to evaluate the relationship of the propagation map to both the voltage mapping and successful site of ablation in patients who underwent ablation for AVNRT. All patients ≤20 years of age who underwent voltage mapping for AVNRT were included in this study. Patients were excluded if they had congenital heart disease or inadequate voltage point density within the triangle of Koch (TK). During the study, a propagation map was evaluated from the prior voltage map, marking a "wave collision" at the site of atrial wave convergence. Patient and procedural information, the location of the wave collision, the site of successful ablation, and the appearance of the voltage map were evaluated. Ultimately, 39 patients aged from four years of age to 20 years of age were evaluated. Success was achieved in 100% of patients, with a recurrence rate of 2.8% and no long-term complications observed. The average procedure time was 127 min. Follow-up length averaged seven months post operation. Low-voltage areas, and a wave collision, were present in all patients. This wave collision was typically located within the TK. The median number of ablations required for successful outcome was two. The successful ablation lesion was typically located over a low-voltage area within 4 mm of the wave collision within the TK. In conclusion, we found in this retrospective evaluation that propagation mapping resulted in a wave collision within the TK, and that the successful ablation site in the majority of patients was near a low-voltage area within 4 mm, typically superiorly, to the wave collision within the TK.

Keywords: Ablation; atrioventricular nodal reentry; propagation mapping; three-dimensional mapping; voltage mapping.

Conflict of interest statement

The authors report no conflicts of interest for the published content. The authors report receiving no financial support for the study discussed. Institutional review board approval was obtained at both the University of Wisconsin and the University of Iowa before beginning this study. An ethics review was included in this approval.

Copyright: © 2017 Innovations in Cardiac Rhythm Management.

Figures

Figure 1:

A: An example of a left lateral, slightly posterior/inferior, view of the atrial septum displaying a voltage map. Note that the His-bundle markers (“HIS” in blue), as well as the CS, are designated. The blue sphere represents the successful site of cryotherapy. The wave collision is marked as the green line just above the “.COLLISION” label. The light gray area on the atrial surface represents a voltage < 0.2 mV, with the color gradient changing to purple with voltages > 2.0 mV. B: This figure is the same geometry as A but with a still frame of the propagation map. The green line represents the marked wave collision, just above the label of “.COLLISION.” The white represents the wave propagation, with the wave front on the purple atrial geometry, proceeding in the direction of the arrows. The wave fronts collide at the marked wave collision. The His-bundle (“HIS” in blue) and the CS are labeled. C: This figure uses the same geometry as seen in A, but with the propagation map displayed as an activation map. Each change in color represents a consistent segment of time of atrial activation, from earlier (in white) to later (in purple). The more pronounced the changes in activation map color, the slower the conduction. Note the slower conduction through the superior TK, with a more rapid conduction posterior to the CS and superior to the site of the wave collision.

Figure 2:

Propagation wave collision and successful ablation site. An illustration of the TK is outlined; His bundle (His), coronary sinus (CS) os, and tendon of Todaro (TT). The wave collision for each patient is represented as a black line. The individual’s wave collision is connected to the site of successful ablation, with green lines connecting the site of the center of a successful lesion, which is closer to the AV node than the wave collision; and red lines connecting successful lesions further from the AV node. In 87% of the patients, the center of the successful ablation site was located on or above the wave collision. Though the successful lesion sites are represented by a small circle at the center of the successful site marked on the 3D map, it should be noted that the typical lesion was 6 mm in diameter, substantially larger than the representative circle seen in this figure.

Figure 3:

The estimated average wave collision and ablation site. This figure shows a representation of the TK and the estimated average site of wave collision and location of successful lesion creation.