AIMS
Given its role as a conduit for transmitting visceral pain signals from the abdominal organs to the central nervous system, neurolytic blockade of the celiac plexus is an accepted pain management approach. Here we evaluate the feasibility of an alternative approach, which involves endovascular ablation of nerves supplying the pancreas via the celiac ganglia using a dedicated radiofrequency (RF) catheter.

METHODS AND RESULTS
Three Yorkshire pigs underwent a single interventional procedure on Day 0 under angiographic guidance in which RF ablations were performed using a single RF-electrode catheter (Autonomix RF Ablation Catheter and Generator System, TX) for 60 sec at a target temperature of 50 oC. The ablation device is a 5Fr steerable catheter with a 4mm surface treated metal electrode and multi-durometer distal section. This allows adequate wall apposition force while maintaining an articulation diameter ≤30 mm. The RF Generator system is an impedance and power-controlled sine wave generator with 50 W max power output at 100 Ω and 460 kHz ± 3% lesion waveforms. Three ablations were performed along the splenic artery (distal, mid, proximal sites), two ablations along the common hepatic artery (distal and proximal sites), and up to four ablations were performed in the celiac artery in a circumferential manner. The animals were euthanized on Day 30 ± 2, a limited necropsy performed, and the treated vessels were rinsed and perfusion fixed/collected in 10% formalin. The arteries were paraffin processed and stained with hematoxylin and eosin (H&E) and Masson’s Trichrome (MT) for histopathologic evaluation and anti-tyrosine hydroxylase (TH) was used as a specific immunohistochemical (IHC) marker for efferent sympathetic nerve fibers (norepinephrine synthesis). Mean nerve abundance per treated section was approximately 2-fold lower in splenic artery sections (38±11.6) compared to sections from the celiac artery (75.7±21.5) and common hepatic artery (81.3±19.9). As expected, circumferential treatment of the celiac artery resulted in a higher group-mean maximal ablation width (19.1±12.6 mm) compared to both the common hepatic artery (7.8±1.9 mm) and splenic artery (6.4±1.4 mm). Notably, maximal ablation depths were largely determined by the locations of periarterial heat sinks (veins and lymph nodes) and was greatest in the celiac artery (12.7±12.9 mm) followed by the common hepatic artery (3.9±1.4 mm) and splenic artery (3.0±1.6 mm). All treated celiac, hepatic, and splenic arteries exhibited histological evidence of nerve degeneration/necrosis and injury with high circumferential involvement: averaging 83% in the celiac artery, 100% in the hepatic artery, and 97% in the splenic artery. The celiac artery showed the most pronounced nerve degeneration/necrosis with mild to moderate changes based on H&E analysis. In contrast, the hepatic artery demonstrated the most extensive nerve injury based on TH IHC, characterized by very weak/patchy staining to no staining. Across all arteries, TH IHC staining produced higher average percent injury scores compared to H&E, indicating greater sensitivity in detecting nerve changes.

CONCLUSIONS
Combined endovascular ablation of the celiac artery, common hepatic artery and the splenic artery using the novel Autonomix RF Ablation Catheter and Generator System is feasible and effective. High maximal ablation width and depths resulted in near complete nerve ablation across the three treated arterial beds.