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Linear lesions in myocardium created by Nd:YAG laser using diffusing optical fibers: In vitro and in vivo results
Author(s) -
Fried Nathaniel M.,
Lardo Albert C.,
Berger Ronald D.,
Calkins Hugh,
Halperin Henry R.
Publication year - 2000
Publication title -
lasers in surgery and medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 112
eISSN - 1096-9101
pISSN - 0196-8092
DOI - 10.1002/1096-9101(2000)27:4<295::aid-lsm2>3.0.co;2-t
Subject(s) - ablation , in vivo , biomedical engineering , laser , materials science , irradiation , medicine , optics , physics , microbiology and biotechnology , nuclear physics , biology
Background and Objective Linear lesions may be necessary for successful catheter ablation of cardiac arrhythmias such as atrial fibrillation. This study uses laser energy delivered through diffusing optical fibers as an alternative to radiofrequency energy for the creation of linear lesions in cardiac tissue in a single application. Study Design/Materials and Methods Samples of canine myocardium were placed in a heated, circulating saline bath and irradiated with a 1.06‐μm, continuous‐wave Nd:YAG laser during in vitro studies. Laser ablation was then performed in vivo on the epicardial surface of the right ventricle during an open‐chest procedure by using similar ablation parameters. Laser energy was delivered to the tissue by being diffused radially through flexible optical fiber tips oriented parallel to the tissue surface. Histology and temperature measurements verified transmurality, continuity, and linearity of the lesions. Results Peak tissue temperatures measured in vitro remained low (51 ± 1°C at the endocardial surface, 61 ± 6°C in the mid‐myocardium, and 55 ± 6°C at the epicardial surface) with no evidence of tissue charring or vaporization. Lesion dimensions produced in vitro and in vivo were similar (depth, 6 mm; width, 8–10 mm; length, 16–22 mm), demonstrating that tissue perfusion in vivo did not significantly alter the heating. Conclusion Long linear lesions, necessary for duplication of the surgical maze procedure during catheter ablation of atrial fibrillation, may be created by using laser radiation delivered through flexible diffusing optical fiber tips. Further development of steerable catheters for endocardial atrial ablation and studies correlating thermal damage zones with electrophysiologic indicators of irreversible conduction block are warranted. Lasers Surg. Med. 27:295–304, 2000. © 2000 Wiley‐Liss, Inc.