Vergleich von Nd:YAG-Abstands-Laser mit Hochfrequenzstrom zur Schaffung kontinuierlicher und transmuraler Ablationen am Vorhof des Schweineherzens

Introduction: In the Maze procedure to treat atrial fibrillation, some surgical incisions may potentially be substituted by ablation techniques. The present study compares the efficacy of radiofrequency current and Neodymium:Yttrium Aluminium-Garnet Laser to create continous and transmural lesions. Non-contact lasing was used as a usual laser mode. The porcine heart was used as an experimental model because of its similar anatomical structure with human heart. Methods: Fresh swine hearts were baught at the slaughter house and stored cool until use. As radiofrequency source, the HAT 200 (Fa. Osypka, Germany) was used in a power controlled mode. A Webster ablation catheter with a 4 mm tip had a pressure of 10g on its tip. The Neodym:Yttrium-Aluminium-Garnet Laser MY 60 (Fa. MArtin, Germany) was connected to a commercially available non-contact catheter that was flushed with carbondioxide(provided by Angeion, USA). The catheters were automatically dragged with a certain speed. 1391 lesions were delivered to 4 previously defined anatomical locations: 1.ostia of the pulmonic veins 2.trabeculated part of the left atrium 3. sinus venarum cavarum (posterior smooth part of the right atrium) 4.Isthmus between tricuspid valve and inferior vena cava. On macroscopic examination the lesions were examined and transmural and continuous ablation line was counted as success. Results: Its possible to create linear transmural lesions in the atria of swine hearts with both methods. More often and mor severe carbonisation occured using radiofrequency current. Under this conditions its not possible to create transmural lessions in the trabeculated part of the left atrium with the radiofrequenzy current. For access without destruction of the tissue you can use for the Laser probe more different settings than for the radiofrequency current. Conclusion: Studies at ex-vivo swine hearts demonstrate that the use of Nd:YAG laser with a fiber in the non-contact mode may be more successful to create long linear lesions than radiofrequency current.