Radiofrequency Ablation With a Retractable Needle‐Tipped Catheter in the Interventricular Septum of Healthy Dogs

INTRODUCTION: Hypertrophic obstructive cardiomyopathy is characterized by hypertrophy of the interventricular septum with the presence of significant left ventricular outflow tract (LVOT) pressure gradients, and one approach to reduce LVOT pressure gradients in this context is through endocardial radiofrequency catheter ablation (RFCA). However, the therapeutic effects of current treatment methods remain to be better improved. Here, we tested the efficacy of RFCA using a retractable needle-tipped catheter (needle catheter). METHODS AND RESULTS: Eight healthy dogs underwent RFCA of the interventricular septum using a needle catheter (n = 4) or a cold saline perfusion catheter (conventional catheter, n = 4). Following each procedure, cardiac structure and function, including the thickness as well as movements of the interventricular septum, were assessed by echocardiography pre-ablation, 1-month and 3-months postablation, and lesions created by each of the two catheters in the healthy dogs were identified by Masson's staining. Three months after RFCA, compared to samples manipulated using conventional catheters, septal movement was significantly reduced in samples treated with needle catheters. Masson's staining indicated that lesions created by the conventional catheter were on the endocardial surface, while lesions created by the needle catheter were delectable under the endocardial surface, and were also found to be deeper and more expanded. CONCLUSIONS: Ablation of the interventricular septum in healthy dogs using a needle catheter led to more pronounced effects on septal movement compared to procedures using a conventional catheter, without compromising safety.