Neodymium: YAG contact laser photocoagulation of the in vivo canine epicardium: Dosimetry, effects of various lasing modes, and histology

Abstract

Significant linear correlation was found between the total delivered energy and all measured lesion parameters. Transmural lesions were found at energy levels of 270-480 J. Maximum depth measured up to 1.68 cm; at high energies, it was limited by myocardial thickness only. At constant energy levels, power and lasing time did not independently affect lesion dimensions; lasing mode and fiber mode had statistically significant but minor effects. Laser lesions were homogeneous and sharply demarcated without epicardial crater or endocardial thrombus formation. Endocardial surface cooling by circulating blood and the presence of epicardial vessels resulted in modifications in lesion morphology. In 29 out of 74 grossly transmural lesions, there was a 0.082 +/- 0.127 cm thin surviving subendocardium. Forty-five coagulation lesions were truly transmural with no surviving myocardial strands. In conclusion, contact epicardial LPC can result in deep, transmural myocardial coagulation lesions. Lesion dimensions can be adequately controlled by total delivered energy. Closed heart epicardial Nd:YAG laser photocoagulation could become a new, less invasive surgical technique for the treatment of drug-resistant ventricular tachycardia.

Laser catheter coagulation of normal and scarred ventricular myocardium in dogs

“…Since the first intracardiac application of laser light [18,19], a variety of catheter designs have been used for ablation of ventricular myocardium [20][21][22][23]. As shown in this study, by means of preshaped self-guiding catheters, the lateral and posterior left ventricular walls can be targeted quickly.…”

Laser photoablation of experimental post-infarction ventricular tachycardia guided by three dimensional activation mapping

“…A continuous low rate saline drip at 5 ml/min was flushed through the tube. Epicardially contacted laser irradiation was performed by manually holding the optical fiber complex perpendicular to the surface of the heart [20]. Laser irradiation at the fiber tip was set at 50 or 60 watts with 10 seconds pulses.…”

“…Nd:YAG laser has been proven to be an effective energy source in the ablation of VT. Laser irradiation can successfully ablate malignant VTs in patients in the operating room [5][6][18][19]. Epicardially delivered laser irradiation can result in deep, transmural myocardial coagulation lesions [5][6][18][19][20].…”

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

“…Previous studies of myocardial ablation using Nd:YAG laser have mainly focused on making lesions suitable for ablation of ventricular tachycardia. Littmann et al [7] examined the morphology of lesions produced by using a variety of duration and power combinations (10±20 W and 6±24 seconds) but did not identify combinations suitable for production of deep narrow lesions. However, we found that higher power (60 W), shorter duration (1 second), and intermittent delivery favored the formation of deep narrow lesions.…”