Principles Guiding PFA Cardiac Catheter and Sheath Management from Preclinical Assessment of Microbubble Formation and Air Intrusion Models

BACKGROUND: Pulsed field ablation (PFA) may create gaseous microemboli, large tip catheters being a potential risk factor for further air intrusion. However, scant characterization exists for how optimization of catheter and sheath handling impacts the microembolic load when handling large tip devices. As most PFA catheters for treatment of atrial fibrillation have large tips, strategies to reduce gaseous emboli are critical. OBJECTIVE: To quantify microbubble formation and air intrusion of a PFA variable-loop circular catheter (VLCC) with a compatible guiding sheath during electrophysiology procedural steps under varying parametric conditions. METHODS: Three preclinical models were used. In an in vivo porcine model, blood was redirected from the carotid artery into an extracorporeal loop connected to an ultrasonic microbubble detector. Similarly, a benchtop in vitro circulating model was used with a microbubble detector. Lastly, negative pressures were simulated on the benchtop to evaluate sheath handling steps and the potential for air intrusion as measured by a syringe. RESULTS: Catheter insertion through a sheath has a sevenfold higher proportion of bubbles >7nL than ablation with the VLCC catheter. Microbubble volume during insertion was reduced by 22%, 67%, and 78% with sheath submersion, irrigation, and aspiration, respectively. Air intrusion decreased by 55%, 56%, 65%, and 57% with sheath stopcock management, aspiration, irrigation, and slower sheath advancement, respectively. CONCLUSION: Among the steps evaluated, catheter advancement through the sheath constitutes the most substantial procedural factor that may contribute to gaseous embolization. Careful management of these devices may mitigate embolic risk.