Production of narrow but deep lesions suitable for ablation of atrial fibrillation using a saline-cooled narrow beam Nd:YAG laser catheter

BACKGROUND AND OBJECTIVE: Lines of radiofrequency ablation for cure of atrial fibrillation are broad, and the consequent loss of atrial mass may impair atrial function and contribute to the risk of stroke. We studied whether Nd:YAG laser could produce deep but narrower lesions. STUDY DESIGN/MATERIALS AND METHODS: Laser lesions were made in ventricular myocardium of nonperfused ovine hearts and at thoracotomy in dogs. RESULTS: Lesions were well demarcated, deep, and narrow. Saline irrigation prevented crater formation for energy levels below 200 J. Lesion depth increased with increasing duration of ablation (maximum 5.3 +/- 0.8mm, P < 0.01). The depth to width ratio was >1 in all cases (maximum 2.5 +/- 1.6). The narrowest lesions were made by using high power, short duration of exposure, and intermittent delivery. CONCLUSIONS: Irrigated Nd:YAG laser can be used to make deep narrow myocardial lesions without crater formation. Laser ablation may be more suitable than radiofrequency ablation for intraoperative or catheter-based cure of atrial fibrillation.