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

Abstract

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.

Inter-ventricular Septum Ablation for the Treatment of Hypertrophic Obstructive Cardiomyopathy

“…However, the injection of absolute ethanol in the wrong location during surgery may cause myocardial necrosis and scar formation, which may lead to severe complications, such as complete heart block, persistent ventricular tachycardia, ventricular fibrillation, cardiac arrest, ventricular septal perforation, and pericardial effusion [14]. In addition, the anatomical variation of hypertrophic ventricular septum and the amount of alcohol will also cause unknown risks to PTSMA [8]. The optimum dose of alcohol injected into the target blood vessel can produce the most appropriate infarct size, so as to achieve the greatest clinical and hemodynamic effects [12].…”

“…He et al [8] used 6 normal domestic dogs as the research subjects. A 21G needle was inserted into the apical region of the right-side ventricle through the parasternal section of the left ventricular long axis, and the insertion angle α was less than 45 °.…”

“…Several treatments are available to relieve or eliminate symptoms and provide protection against SDC, providing a great opportunity for the vast majority of HCM patients to achieve normal longevity with excellent quality of life [6]. Therefore, the current research aimed to assess how to enlarge the diameter of left ventricular outflow tract (LVOT) and effectively reduce LVOT obstruction (LVOTO) [8].…”

Septal Reduction Using Transvenous Intramyocardial Cerclage Radiofrequency Ablation

“…Recently Liu et al. ( 13 , 14 ) reported transthoracic needle radiofrequency (RF) ablation for HCM. Under general anesthesia and transthoracic echocardiography (TTE) guidance, a long 17G RF ablation needle was inserted into the hypertrophied interventricular septum through the chest wall and apical myocardium in 15 patients with HCM.…”