Laser versus radiofrequency catheter ablation of ventricular myocardium in dogs: a comparative test.

To compare the effects of laser light with those of radiofrequency (RF) current on ventricular myocardium, a total of 36 lesions (endocardial approach n = 10 each and epicardial approach n = 8 each) were produced by either transcatheter laser (Nd:YAG, 1,064 nm, 30 W, 30 s) or RF (70 degrees C, 30 s) catheter applications in the beating hearts of 4 dogs. Volumes of coagulated myocardium in endo-/epicardial approaches were 996 +/- 73/1,075 +/- 82 (laser) and 111 +/- 38/44 +/- 5 mm3 (RF). RF lesions showed intramural bleeding, rupture and dissociation of myocardial fibers, tissue vaporization with crater and thrombus formation. Transcatheter application of laser light produced significantly larger and better reproducible lesions than RF current, without undesirable effects on the ventricular walls.