Transcatheter neodymium-yttrium-aluminum-garnet laser coagulation of canine ventricle using a balloon-tipped cardioscope

Echocardiography-guided percutaneous per-ventricular laser ablation of ventricular septum: in vivo study in a canine model

Surgical myectomy and ethanol ablation are established intervention strategies for left ventricular outflow obstruction in hypertrophic cardiomyopathy. Safety and efficacy limitations of these interventions call for a minimally invasive, potentially safer, and more efficacious strategy. In this study, we aimed to evaluate the feasibility of echocardiography-guided percutaneous per-ventricular laser ablation of a ventricular septum in a canine model. Six domestic dogs were chosen for the study. A 21G needle was inserted into the right ventricle with its tip reaching the targeted basal to mid-septum, after which laser ablation was performed as follows: 1-W laser for 3 min (180 J) at the basal segment and 5 min (300 J) at middle segment of the septum, respectively. Echocardiography, blood chemistry tests, and pathology examination were performed to assess the results of laser ablation. No death or major complications, i.e., tamponade, pericardial effusion, or ventricular fibrillation, occurred. The laser-ablated areas were well demarcated in the results of the pathological examination. The diameters of the ablated regions were 4.42 ± 0.57 and 5.28 ± 0.83 mm for 3 and 5 min ablation, respectively. Pre-ablation and post-ablation, cardiac enzymes were found to increase significantly while no significant differences were found among M-mode, 2D (LVEF), pulsed-wave (PW) Doppler, and tissue Doppler imaging (TDI) measurements. Contrast echocardiography confirmed the perfusion defects in the ablated regions. Microscopically, the ablated myocardium showed coagulative changes and a sparse distribution of disappearing nuclei and an increase in eosinophil number were observed. Our study suggests that percutaneous and per-ventricular laser ablation of the septum is feasible, potentially safe and efficacious, and warrants further investigation and validation.

Modification of atrioventricular conduction in dogs by laser irradiation of Koch's triangle guided by balloon-tipped cardioscope

PURPOSE

This study assessed the feasibility of modification of atrioventricular (AV) conduction under direct vision with a new ablation system using laser energy.

METHODS AND RESULTS

In 23 anesthetized dogs, a combined laser and balloon-tipped endoscope was introduced into the right atrium after right thoracotomy. Koch's triangle was easily identified in all dogs endoscopically. Nd:YAG laser energy was delivered through an optical fiber positioned inside the saline-filled balloon to the middle portion of Koch's triangle in eight dogs (mid-Koch group) and to the posterior portion in 12 dogs (postero-Koch group). Complete AV block was achieved in five of eight dogs in the mid-Koch group. In the postero-Koch group, anterograde Wenckebach cycle length increased significantly from 178+/-23 ms to 202+/-37 ms (P = 0.008).

CONCLUSION

Selective laser ablation of Koch's triangle is feasible with a combined laser and balloon-tipped endoscope.