Open-irrigated laser catheter ablation: influence of catheter-tissue contact force on lesion formation

Laser catheter ablation of long- lasting persistent atrial fibrillation: Longterm results

Catheter ablation of atrial fibrillation (AF) is a current therapeutic option but its efficacy for the treatment of long-lasting persistent AF (l-lpAF) remains suboptimal. We tested the laser method as an alternative for catheter ablation of l-lpAF by using an open-irrigated electrode laser mapping and ablation (ELMA) catheter. Laser ablation was attempted in 48 patients aged 50-81 years (69 ± 7.6 y, female = 28) with drug resistant (3.5 trials) l-lpAF (≥12 months). All of the patients had comorbidities: congestive heart failure NYHA II-III (100%), hypertension 29 (60%), coronary artery disease 19 (40%), and heart valve defect 17 (35%). None of the patients had diabetes or obstructive sleep apnea. All were in AF at the beginning of the procedure. Continuous wave (cw) 1064nm Nd:YAG laser applications at 15W/10-20s (14-26/patient) were applied via the ELMA catheter until local electrical activity displayed on the monitor in the bipolar focused local electrograms (LEG) recorded via the pin electrodes from the tip of the catheter was abolished permanently and sinus rhythm was achieved. Online monitoring of electrical potential amplitudes in the focused LEG recorded via the pin-electrodes of the ELMA catheter allowed for validation of ablation success. Procedure duration ranged from 82-175 min (118 ± 72 min), number of lesions were14-26 (19 ± 4) per patient and X-ray exposure times ranged from 15-82 min (23.2 ± 12 min). Interventions were without complications. After the ablation procedure all the patients were in sinus rhythm, off medication, however, 12 (25%) needed a repeat study for various arrhythmias. During followup of 9 months to 29.3 years (8.2 ± 6.5 years) patients' quality of life improved significantly and during final follow-up control all except two were off medication still in sinus rhythm (lifelong success rate = 96%). As compared to other catheter ablation methods the laser method is an intriguing alternative for catheter ablation of l-lpAF.

Influence of catheter orientation on lesion formation in bovine myocardium by using an open-irrigated laser ablation catheter

Lesion sizes and quality are crucial for successful catheter ablation procedures. We sought to test the influence of catheter orientation towards the endocardial surface on lesion formation in bovine myocardium by using an open-irrigated laser ablation catheter. Continuous wave 1064-nm laser catheter applications at 15 W (4.5 W/mm²)/30 s, (135 J/mm²), irrigation flow 30 mL/min, were aimed at the left ventricular endocardial surface of bovine myocardium. The catheter was kept in vertical, in slanting (67.5°, 45°, 22.5°), and in flat positions; in flat position, also 60 s of radiation times were applied (n = 10, each). Lesions were evaluated morphometrically. Maximum depth of lesion was achieved with the catheter in a vertical orientation. Catheter inclination of <22.5 showed a highly significant decrease of lesion depth from 5.6 ± 1.1 to 3.7 ± 0.5 mm (p = 0.0001). In a flat catheter position, laser radiation of 30 s achieved the smallest lesions. However, after 60 s of radiation, the flat lesions were similar in depth (p = 087) and were larger in width (p = 0.0004) and in volumes (p = 0.0025) as compared to the lesions achieved with the catheter in vertical position after 30 s of radiation. Steam-pop with intramural cavitation or tissue vaporization with crater formation did not occur. Longer radiation times can achieve larger lesions regardless of catheter orientation. Catheter orientation is not a major determinant for laser ablation lesion size and quality, and a steerable support may not be needed when using the open-irrigated electrode-laser mapping and ablation (ELMA) catheter RytmoLas.