Techniques for reducing air bubble intrusion into the left atrium during radiofrequency catheter and cryoballoon ablation procedures: An ex vivo study with a high-resolution camera

Background Air embolisms are serious complications during catheter ablation procedures. Objectives The aims of the present study were to determine when air bubbles enter the left atrium (LA) during catheter ablation procedures and to identify techniques that reduce air bubble intrusion. Methods An ex vivo study was performed to monitor air bubbles using a silicone heart model and a high-resolution camera. In total, 280 radiofrequency catheter and cryoballoon ablation processes were tested. Results Small and large air bubbles were often observed during catheter ablation processes. Many small air bubbles arose during sheath flushing at fast speeds (15 mL/2 s) (median bubble number [quartiles]: 35 [20–53] for SL0, 35 [23–44] for Agilis, and 98 [91–100] for FlexCath) and during initial cryoballoon inflation/freezing/deflation (34 [22–47]). Large (≥1.5 mm) air bubbles were observed during Lasso catheter insertion (1 [0–1]), cryoballoon insertion (2 [1–2]), and initial inflation/freezing/deflation (1 [1–3]). Massive air bubbles were observed during Optima catheter insertion into the sheath using an inserter (10 [2–15]). Sheath flushing at slow speeds (15 mL/5 s) significantly reduced the number of air bubbles. Before cryoballoon insertion, temporary balloon inflation and air bubble removal from the inflated surface were most effective in reducing air bubble intrusions. Optima catheter insertion without an inserter significantly reduced large air bubble intrusion. Conclusion Air bubbles entered the LA at specific times. Techniques such as sheath flushing at slow speeds, temporary cryoballoon inflation before insertion, inserting the Optima catheter without an inserter, and avoidance of negative pressure in the LA could reduce air bubble intrusion.