Linear lesion formation by ND : YAG laser versus radiofrequency energy in porcine atria

The efficacy of RF energy versus the neodymium :yittrium aluminum-garnet la ser to create linear lesions was compared in fresh ex vivo swine hearts. A fetal of 598 lesions were created in four locations: ostium of the pulmonar y veins, trabeculated lateral left atrium, smooth posterior part of the rig ht atrium, and the isthmus between the inferior vena cava and tricuspid val ve. A 400-mum bare quartz fiber with CO2 cooling (distance to the tissue 5, 10, and 15 mm) and an RF ablation catheter (4-mm tip) were mechanically dr agged over the tissue at speeds 0.5, 1.0, and 1.5 mm/s. A continuous and tr ansmural ablation line was recorded as successful. A 100% success rate was achieved at the pulmonary veins and the isthmus at some settings of energy delivery by the laser and RF. In the thick posterior right atrium, RF resul ted in transmural lesions only when associated with carbonization, while th e laser produced successful ablation lines in 100% of the attempts. In the left atrium, because of the presence of prominent trabeculations, RF was un successful at all settings of energy delivery. in contrast, deep photocoagu lation by laser resulted in successful ablations in the left atrium in 100% of attempts. Lesion formation was faster by laser ablation and mean lesion width was at least 25% smaller with the laser than with RF. In conclusion, the formation of linear lesions at the isthmus and at the pulmonary veins was successful with the laser and RF. In the trabeculated left atrium and t he thick posterior right atrium, only laser ablation was successful.