Laser catheter coagulation of normal and scarred ventricular myocardium in dogs

Background and Objective Larger lesions would increase success rates of catheter ablation of ventricular arrhythmias. Therefore, improved radio frequency current application techniques, but also alternative energy sources, are being investigated. The purpose of this study was to determine morphology and dimensions of ventricular lesions induced by transcatheter application of laser energy. Material and Methods: A total of 244 lesions were produced by Nd:YAG laser pulses, 1,064 nm, 10–30 W, 15–60 s, percutaneously (endocardial approach, n = 124) and under visual control (epicardial approach, n = 120) in the left ventricular walls of 24 anesthetized dogs. Results Dimensions of lesions increased with the amount of energy applied. Maximal values were obtained at 20 W, 60 s: depth = 12.6 ± 1.1 mm (transmural); width = 15.0 ± 2.8 mm; volume = 1,582 ± 777 mm3. Volumes of lesions did not change significantly when induced through previously scarred myocardium. Histologically, lesions were clear‐cut, without crater or thrombus formation. Procedures and follow‐up periods of up to 22 months were without complications. Conclusion Nd:YAG laser pulses at 10–20 W and 15–60 s produce homogeneous myocardial lesions of coagulation necrosis of reproducible sizes, in a controllable manner, without unwanted effects on the ventricular walls, in normal and through scarred myocardium of dogs. The laser method is a promising alternative for ablation of ventricular arrhythmias including candidates with ischemic heart disease. Lasers Surg. Med. 14:109–119, 1998. © 1998 Wiley‐Liss, Inc.