Elsevier

Heart Rhythm

Volume 18, Issue 6, June 2021, Pages 1004-1011
Heart Rhythm

Experimental
Absence of (sub-)acute cerebral events or lesions after electroporation ablation in the left-sided canine heart

https://doi.org/10.1016/j.hrthm.2021.02.015Get rights and content

Background

Irreversible electroporation (IRE) is a nonthermal ablation modality. A 200-J application can create deep myocardial lesions, but gas bubbles are created at the ablation electrode. Cerebral effects of these bubbles are unknown.

Objective

The purpose of this study was to investigate gas microemboli-induced brain lesions after IRE and radiofrequency (RF) ablation to the left side of the canine heart, using magnetic resonance imaging (MRI) and histopathology.

Methods

In 11 canines, baseline cerebral MRI scans were performed. In 9 animals, after retrograde femoral artery access, 12 ± 4 200-J IRE applications were administered in the ascending aorta. In 2 animals, 30 minutes of irrigated 30-W RF ablation using 10–30g of contact force was applied in the left ventricle. At days 1 and 5 after ablation, MRI was repeated. The brain tissue then was histopathologically examined.

Results

All ablations and follow-up were uneventful. Intracardiac echography confirmed gas bubble formation after each IRE application. Neurologic examination was normal. MRI scans were normal in all animals at day 1 and were normal in 10 of 11 animals at day 5. In 1 animal, a single <2-mm-diameter lesion in the right temporal region could not be excluded as a small infarct or early hemorrhagic site. Histopathologic analysis of the same region showed no pathologic changes. In all other animals, gross and microscopic pathology were normal.

Conclusion

MRI images alone or in combination with histologic follow-up did not reveal treatment-related embolic events. Gross and microscopic pathology did not reveal evidence of treatment-related embolic events. IRE seems to be a safe ablation modality for the brain.

Introduction

Irreversible electroporation is a novel, nonthermal ablation modality. Within milliseconds, a single application can create transmural myocardial lesions with no adverse effects, such as coronary artery or pulmonary vein stenosis, persistent phrenic nerve palsy, or esophageal damage.1, 2, 3, 4, 5, 6, 7, 8, 9

Due to electrical phenomena (eg, electrolysis), gas bubble formation can occur.10 Studies on magnetic resonance imaging (MRI)–detected asymptomatic cerebral events/lesions after cardiac ablation have increased awareness of possible cerebral complications.11 Acute and subacute effects of this new energy source on the brain are unknown. In the present study, canine brain tissue was examined for lesions following electroporation or radiofrequency ablation to the left side of the heart.

Section snippets

Methods

All experiments were approved by the Institutional Animal Care and Use Committee of a United States Department of Agriculture (USDA)–registered facility, accredited by the Association for the Assessment and Accreditation of Laboratory Animal Care International. This study was performed in compliance with the Guide for the Care and Use of Laboratory Animals.12

Results

The first 3 animals did not complete the study. One animal was withdrawn before treatment due cerebral asymmetry found during the pretreatment MRI. Two animals died during the treatment phase due to surgical complications resulting in unconvertable ventricular fibrillation in 1 animal and cardiac tamponade in the other animal. These 2 complications could be attributed to a learning curve and getting acquainted with operating on a canine animal model. The remaining 11 animals were successfully

Discussion

Cardiac tissue is commonly ablated by resistive heating as radiofrequency energy is delivered to targeted sites.14 Procedure-associated stroke, as a severe disabling complication, is rare and occurs in <1% of cases. Recent studies have identified symptomatic stroke to be only a minority of cerebral ischemic events, as postablation brain MRI identified new ischemic lesions in up to 50% of cases.15, 16, 17 Positive MRI findings may occur in patients without apparent neurologic deficit and

Conclusion

In this 5-day study, 9 canines were treated with high-energy electroporation treatments and 2 canines were treated with radiofrequency ablations. All treatments were intended to mimic clinical conditions anticipated during the ablation of left-sided cardiac sites. Evidence of solid and gas bubble–induced microembolic brain lesions were sought using radiologic and histopathologic methodologies. MRI scans alone or in combination with histologic follow-up did not reveal treatment-related embolic

References (21)

There are more references available in the full text version of this article.

Cited by (17)

View all citing articles on Scopus

Funding sources: This study was funded by Abbott, Inc. Disclosures: Drs Neven, Feeney, and Donskoy are consultants for Abbott, Inc. Mr Byrd, Mr Fish, Mr Ronald W. Heil, Jr., and Mr Jensen were employees of Abbott, Inc., at the time this study was conducted. Dr Füting has reported that she has no relationships relevant to the contents of this paper to disclose.

View full text
© 2021 Heart Rhythm Society. All rights reserved.