Effect of Left Atrial Ablation Process and Strategy on Microemboli Formation During Irrigated Radiofrequency Catheter Ablation in an In Vivo Model

Abstract

Background-Formation of microemboli during catheter ablation has been suggested as a cause for asymptomatic cerebral emboli. However, it is unknown which part of the process and ablation setting/strategy is most strongly related to this occurrence. Methods and Results-A total of 27 pigs were used. Catheter/sheath manipulations in left atrium were performed in 25 of 27 pigs outfitted with microemboli monitoring systems. Ablations using open-irrigated radiofrequency catheters were performed in 18 of 25 pigs. Two of 27 pigs did not undergo left atrial procedures and were injected with microembolic materials in the carotid artery to serve as positive controls. In total, 334 sheath/catheter manipulations (transseptal puncture, sheath flushing, catheter insertion, pulmonary vein venography, and sheath exchange) and 333 radiofrequency applications (power setting, 30/50 W; point-by-point/drag ablations) were analyzed. High microbubble volume in the extracorporeal circulation loop and a high number of microembolic signals in carotid artery were observed during sheath/ catheter manipulations especially in saline/contrast injections at fast speed and ablations with steam pop. Fast sheath flushing produced significantly higher microbubble volume than slow sheath flushing (median, 12 200 versus 121 nL; P<0.0001). A total of 44 of 126 (35%) blood filters in the circulation loop showed microparticles (thrombus/coagulum and tissue). Most of them were seen after radiofrequency application especially in 50-W ablations, drag ablations, and steam pop. Brain magnetic resonance imaging showed positive-embolic lesions in control pigs. Conclusions-Formation of microbubbles was the greatest during fast saline/contrast injections and steam pops, whereas high-power radiofrequency applications, drag ablations, and steam pops produced most of the microparticles.(Circ Arrhythm Electrophysiol. 2016;9:e003226.

Cerebral micro-embolization during pulmonary vein isolation: Relation to post-ablation silent cerebral ischemia

“…In an elegant in vivo pig model Takami et al [16] performed different catheter, sheath manipulations and ablations while measuring micro-embolization using intracardiac echocardiography, Carotid Doppler, and an extra-corporal circulation loop which included a microbubble counter and blood filters to collect particulas. Significant microbubble formation was demonstrated on ICE, Carotid Doppler and in the loop during PV angiography and sheath flushing at a high flow, while micro-particles were mostly found during catheter dragging and after a steam pop.…”

Mitigating the Risk of Microemboli Formation During Irrigated Radiofrequency Catheter Ablation

“…The results of Takami et al 11 will benefit all those who perform this procedure. It provides us with useful strategies to mitigate microemboli formation and hopefully reduce ACE and stroke.…”

“…In this issue of Circulation Arrhythmia and Electrophysiology, Takami et al 11 report which parts of the procedure during left atrial ablation are related to microbubble and microparticle formation. They elegantly characterize a series of procedures using open-irrigated radiofrequency catheters to determine the sequelae of left atrial radiofrequency ablations of pulmonary vein isolation.…”

“…12 Takami et al 11 describe how the formation of microbubbles was the greatest during fast saline/contrast injections and steam pops. Highpower radiofrequency applications, drag ablation, and steam pops produced most of the microparticles.…”

Innovative Approaches to Assess the Impact and Steps to Decrease the Neurological Consequences of Ablation

“…104 Stabile et al 105 also reported a very low complication rate of permanent sequelae in patients undergoing AF ablation with open irrigation catheters, thus making them a better choice for reducing the impact of neurological consequences during AF ablation. Takami et al 106 noted that during irrigated RF catheter ablation, formation of microbubbles was the greatest during fast saline/contrast injections and steam pops, Relevant reduction for all rates when using periprocedural continued effective oral anticoagulants (warfarin or novel oral anticoagulation agents). SCE: silent cerebral event; MRI: magnetic resonance imaging.…”