Kenzo Hirao, MD; Naohito Yamamoto, MD; Nobuo Toshida, MD; Hiroko Nawata, MD; Naoko Ishihara, MD; Fumio Suzuki, MD; Nobuyuki Miyasaka, MD; Kazumasa Hiejima, MD; Michio Tanaka, MD

Abstract
The feasibility of transcatheter laser ablation of the canine left ventricle (LV) was tested using a newly developed cardioscope. In 17 anesthetized dogs, a combined laser-endoscope catheter, consisting of an endoscope encased in a 7-French flexible catheter with an inflatable and transparent balloon at the distal end, was introduced into the LV via the carotid artery. A 1064-nm neodymium-yttrium-aluminum-garnet (Nd:YAG) laser was delivered by laser optic fiber, which was introduced through the transport channel and positioned inside the saline-filled balloon. In 16 of 17 dogs, the endocardial surface of the LV was clearly observed. Laser energy totaling 500-5,000 J was applied sequentially in 13 dogs and laser irradiation was completed in all but 2 of the dogs. The excised hearts revealed well-demarcated oval-shaped lesions 2.5-9.5 mm deep in 7 of 11 dogs. Histologic sections revealed coagulation necrosis surrounded by a rim of contraction band necrosis. Thus, transballoon laser photocoagulation of the beating LV is feasible. The newly combined laser-endoscope catheter, which is still in its preliminary stages and needs to be improved to increase the success rate of photocoagulation, appears to be a promising alternative modality for catheter ablative therapy for ventricular tachycardia.
(Jpn Circ J 1997; 61: 695-703)

Key Words: Laser coagulation of ventricular myocardium; Angioscopy; Catheter ablation; Ventricular tachycardia

Mailing address: Kenzo Hirao, MD, First Department of Internal Medicine, School of Medicine, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo, J-113, Japan