In vivoanalysis of the origin and characteristics of gaseous microemboli during catheter-mediated irreversible electroporation

Abstract

Aims Irreversible electroporation (IRE) ablation is a non-thermal ablation method based on the application of direct current between a multi-electrode catheter and skin electrode. The delivery of current through blood leads to electrolysis. Some studies suggest that gaseous (micro)emboli might be associated with myocardial damage and/or (a)symptomatic cerebral ischaemic events. The aim of this study was to compare the amount of gas generated during IRE ablation and during radiofrequency (RF) ablation. Methods and results In six 60–75 kg pigs, an extracorporeal femoral shunt was outfitted with a bubble-counter to detect the size and total volume of gas bubbles. Anodal and cathodal 200 J IRE applications were delivered in the left atrium (LA) using a 14-electrode circular catheter. The 30 and 60 s 40 W RF point-by-point ablations were performed. Using transoesophageal echocardiography (TOE), gas formation was visualized. Average gas volumes were 0.6 ± 0.6 and 56.9 ± 19.1 μL (P < 0.01) for each anodal and cathodal IRE application, respectively. Also, qualitative TOE imaging showed significantly less LA bubble contrast with anodal than with cathodal applications. Radiofrequency ablations produced 1.7 ± 2.9 and 6.7 ± 7.4 μL of gas, for 30 and 60 s ablation time, respectively. Conclusion Anodal IRE applications result in significantly less gas formation than both cathodal IRE applications and RF applications. This finding is supported by TOE observations.

Ablation Modalities for Therapeutic Intervention in Arrhythmia-Related Cardiovascular Disease: Focus on Electroporation

“…While IRE overcomes many complications associated with thermal ablation techniques, it does pose some similar risks such as thrombosis, haemorrhage and infection, however these are common to all procedures employing similar access techniques [ 50 ]. Specific to IRE there is an associated risk of electrolysis when untuned current is passed through body fluids with dissolved electrolytes, instigating gas formation [ 97 , 98 ]. One study reported that different current polarity may decrease gas bubble formation as a side-effect of IRE, highlighting that a reduced number of gas bubbles are released when using anodal IRE, compared to RF or cathodal IRE [ 98 ].…”

“…Specific to IRE there is an associated risk of electrolysis when untuned current is passed through body fluids with dissolved electrolytes, instigating gas formation [ 97 , 98 ]. One study reported that different current polarity may decrease gas bubble formation as a side-effect of IRE, highlighting that a reduced number of gas bubbles are released when using anodal IRE, compared to RF or cathodal IRE [ 98 ]. Gaseous microemboli could result in myocardial damage and in some instances with symptomatic cerebral ischemic events due to the obstruction of capillaries [ 98 ].…”

“…One study reported that different current polarity may decrease gas bubble formation as a side-effect of IRE, highlighting that a reduced number of gas bubbles are released when using anodal IRE, compared to RF or cathodal IRE [ 98 ]. Gaseous microemboli could result in myocardial damage and in some instances with symptomatic cerebral ischemic events due to the obstruction of capillaries [ 98 ]. However, the risk of microemboli appears very low with preclinical canine reports by Neven et al detailing that no treatment-related cerebral events occurred due to gas formation during IRE procedures [ 99 ].…”

Novel concepts in atrial fibrillation ablation—breaking the trade‐off between efficacy and safety

“…One clinical cerebrovascular event with MRI correlate occurred each in the pilot study with the monopolar single pulse electroporation system (10 patients) as well as in a cohort of 121 patients treated with the Farapulse system 27,38 . This is particularly noteworthy, as the formation of gaseous microemboli is typically detected by intracardiac ultrasound immediately upon electroporation‐based ablation 40,41 . However, although these concerns had already been articulated by the investigators in the respective pilot studies, none of the subsequent clinical studies systematically evaluated cerebral complications by means of cerebral MRI, thus safety data remains incomplete in this respect.…”

Safety and efficacy aspects of pulsed field ablation catheters as a function of electrode proximity to blood and energy delivery method

“…Evidence that gas bubbles generated from PFA persist and embolize downstream is in the recent study by Groen et al 26 They used a femoral extracorporeal arterial bypass in pigs to measure bubbles originating from 200J multi-unipolar PFA in the left atrium. Their study found that PFA-J o u r n a l P r e -p r o o f generated bubbles (worst case 85 µL volume per PFA application) embolized to the femoral shunt, and their volume was significantly reduced if the anode, not the cathode, is the pole in the atrium.…”