[Percutaneous endocardial Nd-YAG laser energy: experimental studies of ablation of the ventricular myocardium].

The in vitro and in vivo effects of endocardial laser ablation were assessed. Energy was supplied by a Nd-YAG laser (wavelength approximately 1064 nm) and transmitted via a quartz core fiber (phi: 0.4 mm) housed within a specially designed 7 F catheter. In vitro, the effects of increasing output power (5, 10, 20, 40 watt) and impulse duration (1, 2, 4, 8 s) on lesion size were assessed in myocardial preparations of canine hearts. Preparations were superfused with saline or blood, respectively; the distance of the optical fiber to the endocardium was 5 mm. Lesion size increased in diameter (range: 0-4.0 mm) and depth (range: 0-5.2 mm) in a power- and time-dependent manner. Superfusion with blood significantly enhanced the diameter of the lesions, whereas depth of the lesions significantly decreased. In 16 anesthetized mongrel dogs, a total of 52 laser impulses (output power: 10, 20, 40 w; impulse duration: 1, 2, 4 s; energy: 10-160 J) were delivered to apical and apico-inferior sites of the left ventricle. Postmortem, 40 lesions with a diameter of 2.6-19.4 mm and a depth of 3.7-16.2 mm were found. 19 lesions revealed central vaporized craters with a depth up to 11.2 mm. Perforation of the left ventricle occurred in two cases following 80 and 160 J, respectively. In vitro and in the intact animal (in apical and apico-inferior sites of the left ventricle) endocardial laser ablation is feasible to induce distinct myocardial lesions in a power- and time-dependent manner.(ABSTRACT TRUNCATED AT 250 WORDS)