Feasibility and proof of concept of a proprietary non-contact ablation system with low intensity collimated ultrasound

Abstract

Abstract Funding Acknowledgements Type of funding sources: Private company. Main funding source(s): Heailum Medical Inc. Background Utilization of collimated acoustic energy transition as an ablation energy source has the advantage of propagation through blood with negligible absorption. This allows delivery of non-contact, directional and precise ablation lesions to cardiac tissue. In addition, with dual mode ultrasound technology real-time monitoring of the tissue is possible during ablation. Aim To evaluate a proprietary ultrasound-based ablation system in swine and define the characteristics of the isolated ablation lesions and lines performed in-vivo. Methods In female large white swines, bilateral thigh muscle prep ablations were performed using different time and energy ablation parameters while tip to tissue distance measured with the imaging B-mode and set to 10mm. Lesions were analysed for maximal depth and width. Additional assessment for contiguous linear ablation was performed in the thigh muscle, SVC and within the coronary sinus with the transducer rotated to the endocardial direction. Tissue was fixed in formalin and gross pathological examination with lesion measurement was performed. Results 36 distinct ablation lesions were performed in the thigh prep model. No steam pops were observed for any of the lesions. Mean necrotic lesion depth was 5.35 ± 1.5mm, with increased time with greater influence on dimensions compared to small changes in energy delivered (Figure 1). Reversible damage influenced additional 29% of tissue depth, while 55% additional tissue width was reversible. Linear ablation performed at 2.5mm inter-lesion distance showed contiguous lines, with transmural effect in both SVC and coronary sinus. Conclusions A novel ultrasound based catheter ablation has the ability for non-contact effective ablation in cardiac tissue with directional and tailored energy selection to achieve transmural atrial ablation. Additional in-vivo experimentation will allow refinement of this tool for both isolated lesions and linear ablation while enabling tissue visualization.