By Lyndia Personnat, MS3, University of Massachusetts Medical School

Obesity is now considered an epidemic by the World Health Organization [Vairavamurthy] with a prevalence of 36.5% among U.S. adults during 2011-2014 [Ogden]. Approximately 1 in every 3 U.S. adults either have a BMI greater than 30 and are considered obese or have a BMI over 40 and are considered severely obese. Despite the many treatment methods currently available, the incidence of obesity continues to rise. As highlighted in a previous SIR article “Using IR to Treat Obesity” by Arshan Dehbozorgi, lifestyle modifications, bariatric surgery, and pharmacotherapy are all available as treatment options, but depending on the patient, these options may be either inaccessible or yield limited results. Lifestyle modifications may be extremely challenging without adequate social and environmental support. Factors such as lack of access to fresh produce or to walking trails can make this an unsuccessful option for many patients. Although bariatric surgery is effective, it poses the risk of post-surgical complications, long rehab times and high health care costs. Pharmacotherapy options are limited and can be associated with adverse side effects. An ideal solution should be accessible to all patients, have low risk of complications, and allow patients to have long-term control over their weight.

Interventional Radiology is developing an alternative treatment option for the obesity epidemic. The NANOBLOCK procedure, or bariatric embolization, provides a non-invasive solution that utilizes knowledge of the role of hormones in obesity. The hormone ghrelin is known to increase appetite. The NANOBLOCK procedure selectively embolizes the left gastric artery to suppress the body’s production of ghrelin from the stomach. By suppressing the production of ghrelin, the NANOBLOCK procedure provides patients with a catalyst to ultimately take back control of their own weight. The weight loss that patients experience with this procedure is small but large enough to motivate a patient to maintain their weight loss journey. The NANOBLOCK procedure thus may be especially effective in conjunction with lifestyle modifications.

The NANOBLOCK procedure provides many advantages to current options. It is a minimally invasive procedure that can be completed in few hours in an outpatient setting. Patients are able to return home the same day as the procedure, making it convenient for patients who cannot afford to take significant time off from work and other obligations. There are minimal complications since the procedure does not require major incisions that would otherwise increase the risk of post-surgical infections. Lastly, while the application of introducing bead particles to the stomach for the purpose of suppressing ghrelin is new, catheter embolization, the use of small beads in a blood vessel to block blood flow to an area of the body, has been used for decades by interventional radiologists to treat an array of conditions such a gastrointestinal bleeding, uterine fibroids, and aneurysms. Thus, the expertise interventional radiologists already have in embolization techniques makes gastric artery embolization adaptable to practice.

The NANOBLOCK procedure shows much promise based on results from initial studies. Results from 2 current ongoing investigations, Gastric Artery Embolization Trial for the Lessening of Appetite Nonsurgically (GET LEAN) and Bariatric Embolization of Arteries for the Treatment of Obesity (BEAT Obesity) Trial demonstrated that the procedure is safe. The GET LEAN study evaluated 4 patients with a mean BMI of 42.4 and demonstrated an average body weight loss of 20.3 lbs 6 months post-procedure. Only three minor complications that did not require hospitalization were recorded. Similar results were obtained from the BEAT Obesity Trial, which evaluated 5 patients with a mean BMI of 43.8. The study found no adverse events at 30 days post-procedure and found only two minor adverse events: subclinical pancreatitis and a mucosal ulcer that resolved 3 months post-procedure. Patients of the BEAT Obesity study benefited from a mean excess weight loss of 5.9% at 1 month and 9% at 3 months.

Although these initial results are promising, the next challenge for Bariatric Embolization will be to demonstrate long-term efficacy. It has yet to be seen if patients are able to maintain a healthy weight 5 to 10 years after the procedure without any major complications. The adoption of this procedure as a viable option for weight management will also depend on advances in other fields such as surgery and pharmacology. Weight loss surgeries are continuously becoming more minimally invasive and more targeted therapies are being developed. It is important that the NANBLOCK procedure continues to show superior outcomes regarding long-term weight management, complications, health care costs and patient accessibility in order to be a reliable option for the treatment of obesity.


Patient’s Experience:

General Overview of Procedure:


[1] Vairavamurthy, J, et al. “Current and Cutting-Edge Interventions for the Treatment of Obese Patients.” European Journal of Radiology, vol. 93, 2017, pp. 134–142

[2] Ogden, C, et al. “Prevalence of Obesity Among Adults and Youth: United States, 2011-2014. NCHS Data Brief., No. 219, November 2015

[3] NANOBLOCK procedure <>

[4] Gunn, A.J., et al. “A preliminary observation of weight loss following left gastric artery embolization in humans, J. Obesity 2014

[5] Kipshidze, N, et al. “Endovascular bariatrics: first in humans study of gastric artery embolization for weight loss, JACC, Cardiovasc. Intervensions 8 (12) 2015 1641-1644.

[6] Weiss, C. R., et al.  “Clinical safety of bariatric arterial embolization: Preliminary results of the BEAT obesity trial.” Radiology283(2), 2017 598-608.

[7] Bhat, Sangeeta P., and Arun Sharma. “Current Drug Targets in Obesity Pharmacotherapy A Review.” Current Drug Targets, vol. 18, no. 8, Apr. 2017, pp. 983–993.