The rationale behind gastric embolization as a treatment option for bariatric patients Park, Susie; Wolf, Michael; Keating, Lawrence; Englander, Meridith; Mandato, Kenneth; Herr, Allen; Siskin, Gary Albany Medical Center Department of Radiology OBESITY: THE FACTS In 2008, >1.6 billion adults were overweight (BMI ≥ 25) with >400 million considered obese (BMI ≥ 30). The prevalence of obesity continues to increase annually and it is estimated that by the year 2030, >42% of Americans will be obese.1 Being overweight and obese is associated with an increased risk of several diseases including cardiovascular disease (heart disease and stroke), diabetes, certain types of cancer (endometrial, breast, and colon), and osteoarthritis. The annual medical cost of obesity in the United States is $147 billion. HORMONAL FACTORS INFLUENCING APPETITE Recently, the peptide Ghrelin was identified as regulator of long-term appetite regulation and energy homeostasis.2 Ghrelin is a powerful appetite stimulant that is produced in the mucosa of the gastric fundus in response to hunger and starvation, signaling the brain to stimulate feeding.3 Ghrelin release results in increased growth hormone secretion, gastric acid secretion, increased gastric motility, and decreased gastric emptying. Ghrelin administration results in increased appetite and adiposity. Ghrelin levels have been shown to be associated with obesity.4 VASCULAR ANATOMY OF THE STOMACH The left gastric artery most commonly arises from the celiac trunk and runs along the superior portion of the lesser curvature of the stomach, as the primary supply to the gastric fundus. Variant anatomy is common about the celiac trunk and its major branches.5 GASTRIC ARTERY EMBOLIZATION Embolization has been employed in the upper GI tract since the 1970s for the management of gastrointestinal bleeding.6 Ischemic complications rarely occur as a result of the foregut’s rich collateral blood supply.7 Studies have shown the risk of ischemic complication increases with the use of smaller embolic particles, and as a result, some have recommended using particles larger than 500 microns in diameter.8 GASTRIC ARTERY EMBOLIZATION AND OBESITY Bariatric surgery is considered the best long-term treatment for morbid obesity. However, there is risk associated with surgery, and not all patients who would benefit from these procedures are candidates. 9 It has recently been suggested that catheter-directed gastric embolization could serve as a treatment option for bariatric patients. Since ghrelin is principally secreted by the gastric fundus, embolizing the left gastric artery has been proposed as a treatment option for obesity.10 Multiple studies in animal subjects have demonstrated the ability of gastric artery embolization to reduce ghrelin levels and lead to weight loss. However, some of the studies had high complication rates including ulceration, gastritis, and distal esophageal stricture.10-14 In March 2013, the first-in-man study was performed by Kipshidze et al.15 Left gastric artery embolization was performed in 5 patients using BeadBlock Microspheres, a PVA-hydrogel microsphere measuring 300-500 microns in diameter. All patients reported decreased appetite during the first week after the procedure. Weight loss was observed in all patients at 1-month follow-up. The mean initial weight decreased from 128 kg to 114 kg, and the mean initial BMI decreased from 42.3 to 37.9. No complications were observed in this population of patients. CONCLUSION Gastric embolization is potentially an exciting advance in the treatment of obesity for patients who are not considered appropriate candidates for bariatric surgery. It is clear that we need a better understanding of this procedure and its relation to hormone reduction, safety, and long-term outlook. Therefore, significant research is necessary before this procedure can become part of the daily practice of interventional radiology. RESOURCES 1National Center for Health Statistics. National Health and Nutrition Examination Survey. Questionnaires, datasets, and related documentation. 2Kojima M, Hosoda H, Data Y, et al. Ghrelin is a growth-hormone-releasing acylated peptide from stomach. Nature 1999; 402:656-660. 3Kojima M, Kangawa K. Ghrelin: structure and function. Physiol Rev 2005; 85:495-522. 4Wren AM, Seal LJ, Cohen MA, et al. Ghrelin enhances appetite and increases food intake in humans. J Clin Endocrinology and Metabolism 2001; 86:5992. 5Song SY, Chung JW, Yin YH, et al. Celiac Axis and Common Hepatic Artery Variations in 5002 Patients: Systematic Analysis with Spiral CT and DSA. Radiology 2010; 255: 278-288. 6Rosch J, Dotter CT, Brown MJ. Selective arterial embolization: a new method for control of acute gastrointestinal bleeding. Radiology 1972; 102:303-306. 7Poultsides GA, Kim CJ, Orlando R, et al. Angiographic embolization for gastroduodenal hemorrhage: safety, efficacy, and predictors of outcome. Arch Surg 2008; 143:457-461. 8Abdel-Aal AK, Bag AK, Saddekni S, et al. Endovascular management of nonvariceal upper gastrointestinal hemorrhage, Eur J Gastroenterol Hepatol 2013; 25:755-763. 9 Nguyen N, Champion JK, Ponce J, et al. A review of unmet needs in obesity management. Obes Surg 2012; 22:956-966. 10Arepally A, Barnett BP, Montgomery E, Patel TH. Catheter-directed gastric artery chemical embolization for modulation of systemic ghrelin levels in a porcine model: initial experience. Radiology 2007; 244:138-143. 11Arepallly A, Barnett BP, Patel TT, et al. Catheter-directed gastric artery chemical embolization suppresses systemic ghrelin levels in porcine model. Radiology 2008; 249:127-133. 12Bawudun D, Xing Y, Liu WY, et al. Ghrelin suppression and fat loss after left gastric artery embolization in canine model. Cardiovasc Intervent Radiol 2012; Published online 25 Feb 2012. 13Paxton BE, Arepally J, Crow, et al. Bariatric gastric artery embolization for the modulation of systemic ghrelin levels in a porcine model: endoscopic and Histopathologic correlation. J Vasc Interv Radiol 2012; 23(3):S7-S8. 14Paxton BE, Kim CY, Alley CL, et al. Bariatric embolization for suppression of the hunger hormone ghrelin in a porcine model. Radiology 2013; 266:471-479. 15Kipschidze N, Archvadze A, Kantaria M, et al. First-in-man study of left gastric artery embolization for weight loss. J Am Coll Cardiol 2013; 61:E2056. HUNGER GHRELIN Pituitary GH secretion Gastric acid secretion Gastric motility Gastric emptying RESULTING IN Appetite Adipose deposition