Epicardial radiofrequency ablation of ventricular myocardium: Factors affecting lesion formation and damage to adjacent structures

Epicardial radiofrequency ablation of ventricular myocardium: Factors affecting lesion formation and damage to adjacent structures

Author Fenelon, G. Google Scholar
Pereira, K. P. Google Scholar
Paola, AAV de Google Scholar
Institution Universidade Federal de São Paulo (UNIFESP)
Abstract We evaluated the factors affecting epicardial radiofrequency (RF) lesion formation in normal ventricular myocardium. in 16 dogs, a minithoracotomy was made and a sheath was placed in the pericardial space. Standard ablation lesions (4-mm tip catheter; 70 degrees C/60 seconds) were created in each ventricle under fluoroscopy guidance (n = 7) or hand-held with direct visualization of the catheter to assure optimal electrode-tissue contact (n = 6). in the latter, thermally-shielded (TS) electrodes (50% tip surface along its 4 mm length) were used in 3/6 dogs. Catheter tip (4 mm) irrigation (13 mL/minutes; 40 degrees C/60 seconds) was employed with conventional techniques in 3 additional dogs. Results: With optimal electrode-tissue contact (11 lesions), power (3.4 +/- 2.3 W vs. 16 +/- 13 W; p < 0.001) and pacing thresholds (0.2 +/- 0.0 mA vs. 3.6 +/- 5.7 mA; p = 0.004) were lower than standard RF (25 lesions). However, lesion dimensions were similar and transmural lesions did not occur (depth 2.8 +/- 1.1 mm vs. 3.0 +/- 1.5 mm). Catheter irrigation allowed high power outputs (43 +/- 6.1 W; p < 0.001) generating transmural lesions, 5/9 (55%), depth 6.4 +/- 2.1 mm. At constant power (2 W), catheter-tip temperature (52 +/- 5.2 degrees C vs. 57 +/- 6.6 degrees C; p = NS) and lesion (10 in each group) dimensions were similar for conventional and TS electrodes, but damage to parietal pericardium and lungs occurred with conventional electrodes only (70% vs. 0% p = 0.02). Conclusion: Standard epicardial RF ablation does not produce deep lesions and exhibits a significant energy loss probably due to poor electrode-tissue contact. Catheter irrigation allows delivery of high power outputs to the epicardium consistently creating deeper lesions than standard ablation. TS electrodes may reduce damage to neighboring structures during epicardial RF ablation.
Keywords arrhythmias
electrophysiology
radiofrequency ablation
pericardium
Language English
Date 2006-01-01
Published in Journal of Interventional Cardiac Electrophysiology. Dordrecht: Springer, v. 15, n. 1, p. 57-63, 2006.
ISSN 1383-875X (Sherpa/Romeo, impact factor)
Publisher Springer
Extent 57-63
Origin http://dx.doi.org/10.1007/s10840-006-7620-0
Access rights Closed access
Type Article
Web of Science ID WOS:000237341000009
URI http://repositorio.unifesp.br/handle/11600/28637

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