A novel enhanced stability detection algorithm for ablation catheters: purpose and application in high-power short-duration ablation

Figures

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  Figure 1. Time to achieve 350 ablation index target with stability + algorithm in QMODE: This bar chart illustrates the time it took to achieve a 350 ablation index (AI) target during ablation sessions conducted using the Stability + algorithm in QMODE. (A) Sessions are categorized by the time intervals needed to reach the 350 AI target. (B) Out of 933 sessions analysed, AI exceeded 350 within 9 s in 84% of the sessions. This implies that the desired AI level was reached more rapidly than the average time taken by the Gated algorithm to display a VisiTag with a standard respiration rate in 84% of the ablations, indicating overshoot.

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  Figure 2. Comparing the two algorithms and their key features: (A) Respiratory Gated Algorithm: the red dots represent the positions of the catheter tip. The orange line connects two consecutive end-expiration phases, and stability is determined by measuring the difference in catheter tip positions between these points. The system does not take into account catheter tip location during this time (yellow tracing line). (B) Respiration Compensated Algorithm (Stability+): Overall catheter tip movement depicted by the purple line. The white line traces the impact of respiration on this overall movement. Subtracting the white line from the purple line yields the compensated catheter tip movement, indicated by the green line. Stability is based on the absolute value of the compensated catheter tip movement. Images are courtesy of © Biosense Webster, Inc. All rights reserved.

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  Figure 3. Catheter movement analysis and stability evaluation: (A) after few seconds of ablation, we observe a rise in impedance and a drop in temperature, indicating catheter movement. Approximately 3 s after this initial movement, the impedance continues to decrease, while the temperature continues to rise. (B) In the clinical analysis conducted in MATLAB, the catheter exhibited the following behavior: initially stable (1), subsequently moved for a duration of 3 s (2), returned close to its original position (3). Because the movement duration was brief, and the catheter returned sufficiently close to its initial position after the movement, accounting for thermal latency, the stability algorithm would classify the entire session as stable. Images are courtesy of © Biosense Webster, Inc. All rights reserved. Blue Line: Catheter tip trajectory; Blue Dots on Blue Line: 1 s interval markers; White Line: Respiration-induced catheter motion; Red-Light Blue Dashed Line: Compensated catheter motion; Purple Circle: Tag position at 17.6 s into the ablation; Purple Rhomboid: Catheter position at the end of the expiration phase.