Assessment of a "main renal artery + branches" ablation strategy for catheter-based circumferential ultrasonic renal denervation.

This study aimed to evaluate the feasibility of a "main renal artery + branches" ablation strategy for catheter-based circumferential ultrasonic renal denervation (uRDN), with a particular focus on thermal ablation morphology. We characterized peripheral tissues and nerves surrounding the renal artery at various locations and investigated the effects of the renal vein, adjacent arteries, lymph nodes, and ganglia, on the radial propagation of tubular ultrasound and measured their impact on the temperature field and ablation morphology. By correlating ablation morphology with nerve distribution features, we proposed optimized combinations of parameters for main renal artery and branch ablations. These combinations were validated through ex vivo experiments. The study found that the peripheral tissues of the renal artery significantly affect the field of tubular ultrasound. Specifically, veins and other arteries exhibited a greater impact on the thermal field compared to lymph nodes and ganglia. Based on the distribution characteristics of tissues and nerves at different locations, we derived combinations of ablation parameters covering approximately 90% of the nerves at various positions along the renal artery. For example, at an ultrasound power of 15 W, the ablation times needed for the proximal, distal, and first branches of the renal artery were 24 s, 16 s, and 9 s, respectively. Alternatively, at an ablation time of 18 s, the required powers were 19.5 W, 13 W, and 8.5 W, respectively. Ex vivo experiments revealed a deviation from the theoretical predictions of less than 2 °C. These combinations of parameters provide theoretical support for a "main renal artery + branches" ablation strategy in renal denervation surgery. Our findings suggest that the first-order renal artery branch is an optimal target for catheter-based circumferential ultrasonic renal denervation. An ablation radius of 2.5 mm is sufficient to effectively encircle 90% of the nerves, which minimizes energy consumption and procedural duration and prevents damage to surrounding tissues. This ablation strategy, which is based on the combination of the main renal artery and its first-order branch, represents a promising approach for effective renal denervation.