Potential microemboli formation risk and its management during the heated saline-enhanced radiofrequency needle-tip catheter ablation.

Background: The potential risk of embolic events during ablation in the left ventricle (LV) with a heated saline-enhanced radiofrequency (SERF) needle-tip ablation catheter has not been characterized.
Objective: This study aimed to investigate the formation of microemboli or other untoward events during SERF ablation.
Methods: Ninety-three radiofrequency (RF) ablation procedures were performed in the LV of 14 pigs by using a SERF catheter (35 W, 70 seconds, and 60°C; normal or degassed saline [NS or DS] irrigation with a flow rate of 10 mL/min) vs a standard irrigated-tip radiofrequency (S-RF) catheter (30 or 50 W, 30 seconds, and 17 mL/min). Microbubble formation was graded on the basis of intracardiac echocardiography. Microbubbles, microembolic signals, and microparticles were monitored using our established model.
Results: There was no significant difference in microbubble volume among SERF-NS, SERF-DS, and S-RF 30 W with "grade 1" intracardiac echocardiography microbubbles (median and 25th-75th percentiles 0.201 [0.011-3.13], 0.455 [0.06-2.66], and 0.004 μL [0.00-0.16 μL], respectively). There was no significant difference in microembolic signals among SERF-NS, SERF-DS, and S-RF 30 W with grade 1 bubbles (n = 8.0 ± 5.8, n = 7.6 ± 4.2, and n = 6.1 ± 6.1, respectively). Both SERF-NS and SERF-DS created larger lesions than did both S-RF 30 W and S-RF 50 W deliveries (mean 1241.5 ± 658.6, 1497.7 ± 893.4, 75.0 ± 24.8, and 184.0 ± 93.8 mm ³ ; P < .001). There was no significant difference in microparticle incidence among groups (P = .675). No evidence of embolic events was found in the brain and other organs at the histology assessment.
Conclusion: In the setting of SERF ablation, significantly large LV lesions can be created without any increment in embolic microbubble or particle events. Grade 1 microbubble is related to the efficacy and safety.
Competing Interests: Disclosures Dr Packer reported receiving grants from the National Institutes of Health (NIH)/National Heart, Lung, and Blood Institute, St. Jude Medical and St. Jude Memorial Foundation, Biosense Webster, Medtronic, and Boston Scientific during the conduct of the study and receiving grants from Abbott, Biosense Webster, Boston Scientific, CardioFocus, Medtronic, St. Jude Medical, CardioInsight, the NIH, Siemens, Thermedical, Endosense, Robertson Foundation, and Hansen Medical. He reported serving on the advisory board without compensation for Abbott, Biosense Webster, Boston Scientific, CardioFocus, Medtronic, St. Jude Medical, Spectrum Dynamics, Siemens, Thermedical, Johnson & Johnson, and SigNum Preemptive Healthcare; speaking with honorarium from Biotronik and MediaSphere Medical; and receiving royalties from Wiley, Oxford, and St. Jude Medical. Dr Packer and Mayo Clinic jointly have equity in a privately held company, External Beam Ablation Medical Devices (outside the submitted work). In addition, Dr Packer has mapping technologies with royalties paid. Dr Hohmann was funded by the Deutsche Forschungsgemeinschaft (DFG [German Research Foundation]; project no. 380200397). The other authors report no potential conflicts of interest.
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