Ultrasound-Guided Radiofrequency Ablation of Chemodectomas in Five Dogs

SIMPLE SUMMARY: Chemodectomas are rare tumors in dogs. Although brachycephalic breeds seem to be overrepresented, likely due to chronic hypoxia, also non-brachycephalic dogs may be affected. The growth of chemodectomas sometimes leads to compression and/or pericardial effusion; metastases appear infrequently. Therapeutical management includes chemotherapy, surgery, stent placement and radiotherapy. This study describes a novel approach using a minimally invasive technique based on percutaneous ultrasound-guided radiofrequency ablation in five dogs affected by symptomatic chemodectoma. Under general anesthesia and by sonographic guidance, a Leveen electrode, with an umbrella-like configuration, was placed inside the tumor. An alternating current through the electrode produced a spherical volume which increased the temperature, producing tissular necrosis. No complications either during the procedure or in the following days were reported in the five dogs. A rapid clinical improvement was achieved in all the dogs. Changes in the apparent size and echotexture of the mass were also observed. Thermal ablative therapy represents a potential new approach in the clinical management of aortic body tumors. ABSTRACT: Chemodectomas are low prevalence tumors with complex clinical management. Many present as an incidental finding however, in other dogs, they produce pericardial effusion and/or compression, leading to the appearance of severe clinical signs. There are currently several approaches: surgery, radiotherapy, stent placement and chemotherapy. This is the first description of percutaneous echo-guided radiofrequency ablation of aortic body tumors. This minimally invasive treatment is based on high frequency alternating electrical currents from an electrode that produces ionic agitation and generates frictional heat, causing coagulation necrosis. Five dogs with an echocardiographic and cytological diagnosis of chemodectoma underwent percutaneous echo-guided radiofrequency ablation. At the time of presentation, all the dogs showed clinical signs, such as ascites and/or collapse. There were no complications either during the procedure or in the following 24 hours. Rapid clinical improvement associated with a reduction in size and change in sonographic appearance of the mass were achieved with no complications. Six months follow-up was carried out in all dogs. A second percutaneous echo-guided RFA was performed eight months after the first procedure in one dog. Based on our experience, radiofrequency ablation seems to be a feasible and safe technique, making it a potential alternative therapeutic approach in the clinical management of aortic body tumors leading to severe clinical compromise.