EXPERIMENTAL ABLATION OF EMPHYSEMATOUS RAT LUNG WITH ND-YAG LASER - LUNG-CHANGES STUDIED BY HISTOPATHOLOGY AND SEM

Laser ablation has been employed as a therapeutic measure for chronic pulmonary emphysema. As yet, however, its effect is not understood on firm pathological basis. We aimed to study, both histopathologically a nd using Scanning Electric Micrscopy (SEM), the changes produced by ir radiation with contact Neodymium-yttrium aluminum garnet laser (Nd: YA G laser) in rat lungs with experimentally induced emphysema. Emphysema was produced in 34 rats by instilling elastase via airways. Eight wee ks after the instillation, the emphysematous left lung was irradiated under thoracotomy with contact Nd: YAG; laser at a power of 5 watts. T he animals were sacrificed in acute as well as chronic phase for histo pathological observation of lung and scanning electron microscopy. Las er caused necrotic and inflammatory changes in the subpleural zone of lung. Immediately after irradiation, the alveolar septa were destroyed as visualized by SEM, only leaving the elastic skeleton. In a chronic phase, the necrotic zone was collapsed and replaced with a thick fibr ous scar which seemed to serve more or less to keep the organ from bei ng excessively inflated. In this model, irradiation induces subpleural dense scarring, which, by ''encasing'' an emphysematous lung, is expe cted to more or less normalize the excessive compliance. (C) 1998 Toho ku University Medical Press.