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Histologic signatures of thermal injury: Applications in transmyocardial laser revascularization and radiofrequency ablation
Author(s) -
Whittaker Peter,
Zheng Shiming,
Patterson Michael J.,
Kloner Robert A.,
Daly Kevin E.,
Hartman Ray A.
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<305::aid-lsm3>3.0.co;2-w
Subject(s) - birefringence , ablation , in vivo , materials science , laser ablation , laser , myocyte , lesion , biomedical engineering , cardiac muscle , medicine , anatomy , pathology , optics , cardiology , biology , physics , microbiology and biotechnology
Background and Objective Cardiac treatments such as transmyocardial laser revascularization and radiofrequency ablation cause thermal injury. We sought to provide quantitative histologic methods of assessing such injury by using the inherent birefringence of cardiac muscle and collagen; specifically, to exploit the connection between thermal injury and the loss of birefringence. Study Design/Materials and Methods We quantified tissue birefringence changes in vitro for temperatures up to 130°C. This information was used to assess thermal injury associated with myocardial channels made in vitro. We then measured in vivo cardiac injury 30 minutes and 3 days after radiofrequency exposure. Results Birefringence decreased above 60°C for muscle and above 70°C for collagen. Temperatures above 80°C were associated with collagen fiber straightening and above 95°C with little muscle birefringence. Injury adjacent to laser channels was greatest parallel to cell orientation. In vivo, muscle with reduced birefringence was surrounded by cells exhibiting focal birefringence increases (contraction bands). Early injury assessment marked by birefringence changes corresponded to lesion size at 3 days. Conclusion Polarized light revealed histologic temperature signatures corresponding to irreversible muscle injury and collagen denaturation. Lasers Surg. Med. 27:305–318, 2000. © 2000 Wiley‐Liss, Inc.