Transvenous Radiofrequency Ablation of Adrenal Gland: Experimental Study

Abstract

Purpose: The aim was to evaluate a flexible device for transvenous adrenal gland radiofrequency ablation in vitro and in an in vivo animal model.

Materials and methods: A flexible radiofrequency-tip catheter with an inner-cooling mechanism and a guidewire lumen was made. Then, using a polyvinyl alcohol gel model, the ablation diameter was evaluated and how much energy to deliver in vivo was determined. Finally, transvenous radiofrequency ablation of the left adrenal glands of two pigs was performed, delivering 5000 or 7000 J in a single dose to each. The ablation effects were also assessed by histological examination of hematoxylin-eosin-stained sections.

Results: The mean ablation diameters in the gel model were 20.2 and 21.9 mm in the short axis and 15 and 20 mm in the long axis for 5000 or 7000 J, respectively. The device was inserted into porcine left adrenal vein with no complications. The mean ablation diameters were 10 mm in the shorter axis (whole thickness of porcine left adrenal gland) in the porcine model for 7000 J. Transient increases in blood pressure and heart rate occurred during ablation. Histologically, the adrenal gland showed severe necrosis at ablated area. There was venous congestion upstream in a non-ablated area, and thermal damage to surrounding organs was not observed.

Conclusions: A flexible radiofrequency-tip catheter could be inserted successfully into the left adrenal vein. The left adrenal gland was entirely ablated without any thermal damage to surrounding organs. We suggest transvenous adrenal ablation has potential as a therapeutic option for primary aldosteronism.

Keywords: Adrenal venous sampling; Adrenocortical adenoma; Hyperaldosteronism; Interventional radiology; Transvenous radiofrequency ablation.