Dual-atria rotor modification: A comparative analysis of rotor modification and posterior wall isolation in patients with persistent and long-standing persistent atrial fibrillation

Figures

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  Figure 1. The figure shows the method used to calculate the atrial volume using diagnostic imaging software. The top left section shows the original image obtained from a contrast-enhanced computed tomography scan. The software processes the image, reconstructing it into standard voxels and calculating the internal volume. The top right figure shows a visual representation of the right atrium. There is a considerable individual variation in the volume of the left appendage. This individual variation is very important because it can affect the results of this study. For this reason, we have adopted 2 volume indices for comparative analysis. The diagram on the lower left shows the left atrium without appendage, and the diagram on the lower right shows the left atrium with appendage.

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  Figure 2. The figures show an example of phase mapping and low-power radiofrequency ablation. The 2 images in the upper row are fluoroscopic (left anterior oblique views) showing the insertion of a spiral electrode catheter into the atrium, placement of a 20-pole electrode catheter into the coronary sinus, and placement of an 8-pole electrode catheter in the right atrium. The image on the left shows the mapping of the right atrium, and the image on the right shows the mapping position in the left atrium. The image below shows the mapping location of the regions of interest (ROI) displayed on the 3D electro-anatomical model of the EnSite system. The green electrodes on the EnSite system indicate the location of the spiral electrodes, and the mapping location is recorded with a number. The target-ROI for rotor modification is selected by visually analyzing the color phase movies of each ROI. The location where the ablation was performed is indicated with a red tag.

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  Figure 3. The figure shows the analysis screen for phase mapping using the EXT system. On the left side of the screen, a real-time intra-cardiac electrogram is displayed. This shows the bipolar electrogram obtained from a single region of interest (41-poles) using a spiral electrode. On the lower right of the screen, a color phase movie is displayed. The positions of the electrodes related to the intra-cardiac electrogram are indicated by numerical labels in the movie. The depolarization process at each electrode position is indicated by a change in color from red to purple. This process is also explained in Figures 4 and 5.

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  Figure 4. This figure shows the actual color phase movie of the EXT system. The EXT system employs artificial intelligence and deep learning to analyze the electrical activity associated with atrial fibrillation. Based on mapping recordings, the system automatically classifies activation patterns as follows: passive activation (P), non-passive activation (NP), and spiral waves present, which can be further divided into single spiral wave reentry (“R”) and multiple wavelets (“M”). The proportion of NP relative to the total recording time is expressed as %NP. In this specific region of interest, the system measured as follows: NP, 53%; R, 44%; M, 9%; P, 47%. The indicators displayed in blue highlight the rotor status at a given moment. Left image (t = 240 ms/5000 ms): the white frame (added for illustration) marks a phase singularity, indicating a single spiral wave rotation. EXT system classifies this as “R,” and both “NP” and “R” are highlighted in blue. Middle image (t = 2400 ms/5000 ms): Two spiral waves are detected, leading to classification as “M.” Both “NP” and “M” are displayed in blue. Right image (t = 3200 ms/5000 ms): No phase singularities (core) or spiral waves detected,…

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  Figure 5. This figure shows snapshots of a typical rotor observed using a color phase movie from the EXT. The EXT system generates data for the region of interest (ROI) at a rate of 250 frames per second (4 ms/f). This figure shows snapshots of the color phase movie displayed from left to right at 32 ms intervals. Phase map A shows an example where the wavefront has not rotated sufficiently, and the rotor duration is extremely short. In the 0 ms snapshot, the phase singularity (core) is at 3 o’clock in the ROI, and the wavefront is observed in the 12 o’clock direction. After that, the wavefront rotates clockwise, but in the 160 ms snapshot, wavebreak is observed. Phase map B shows snapshots of the case where 2 rotors are observed within a single ROI. In the 0 ms snapshot, 2 rotors with phase singularities (cores) are observed at 12 o’clock and 3 o’clock. The wavefront of the 12 o’clock rotor rotates counterclockwise, while the wavefront of the 3 o’clock rotor rotates clockwise. These 2 wavefronts collide after 128 ms, and the rotors disappear or wavebreak. In the EXT, even in the absence of stable rotation, as seen in these 2 examples, it is classified as non-passive activation due to the…

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  Figure 6. The figure demonstrates an example of the posterior wall isolation procedure. The upper image shows a frontal fluoroscopic view, displaying a ring electrode catheter and a radiofrequency ablation catheter placed in the right pulmonary vein. The lower image shows a 3-dimensional geometry model created by EnSite NavX fusing images. Red tags represent the ablation points. Yellow tags indicate ablation points where power was limited to protect the esophagus. Blue tags show additional ablation points for gaps in the ablation line.

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  Figure 7. This schematic diagram shows the distribution of the locations identified as “target-ROI” based on the classification of wavefront dynamics. The “target ROIs” are indicated by “X” marks in the schematic diagrams of both atria. Each region is labeled with its anatomical terms. The atrial septum is shown from both sides, indicating the locations recorded in LA mapping and right atrial mapping, respectively. The “X” mark indicates the central position of the “target-ROI.” The area of the ROI is 4.3 cm2, and the phase singularity is meandering, the position does not exactly match the “X” position.

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  Figure 8. This figure shows the survival curves analyzed using the Kaplan-Meier method. The analysis was based on the event-free survival rate over a 36-month observation period, and recurrence of atrial tachycardia (AT), atrial fibrillation (AF), and atrial flutter (AFL) was defined as the end point. The log-rank test was used to analyze the survival curves, and the P value was <.05, indicating a statistically significant difference. The number of patients evaluated at each time point is presented in the graph below. The following table shows the data for the duration of the procedure and the number of complications in both groups.