Catheter-directed gastric artery chemical embolization for modulation of systemic ghrelin levels in a porcine model: initial experience

Repeated photodynamic therapy using a chlorin e6-embedded device to prolong the therapeutic effects on obesity

OBJECTIVE

This study aimed to investigate the efficacy and safety of repeated photodynamic therapy (PDT) with a chlorin e6 (Ce6)-embedded intragastric satiety-inducing device (ISD) to maintain therapeutic effects of obesity in a juvenile pig.

METHODS

The Ce6-embedded ISD was fabricated with a dipping method. Twelve pigs were divided into four groups of three and were administered control, single, biweekly, or weekly PDT, respectively. The therapeutic effects were assessed by comparing the results of phototoxicity, endoscopy, fluoroscopy, hormone and weight changes, and histological examination.

RESULTS

The percentage of total body weight gain was significantly suppressed in PDT-treated pigs compared with control pigs (all p < 0.001). This suppression persisted in the repeated PDT groups, but percentage of total body weight gain gradually increased when PDT was stopped. Ghrelin levels in the PDT-treated groups were significantly lower and leptin levels were significantly higher than those in the control group (all p < 0.05). Inflammatory cell infiltration, collagen, TUNEL, and anti-ghrelin-positive deposition in the weekly group were significantly higher than those in the control, single, and biweekly groups (all p < 0.01).

CONCLUSIONS

Repeated and periodic PDT was technically feasible and safe and successfully maintained the therapeutic effects against obesity while eliminating the indwelling time and reducing ISD-related complications in pigs.

Balancing Safety and Efficacy to Determine the Most Suitable Size of Imaging-Visible Embolic Microspheres for Bariatric Arterial Embolization in a Preclinical Model

OBJECTIVES

To identify the most suitable size of imaging-visible embolic agents with balanced safety and efficacy for bariatric arterial embolization (BAE) in a preclinical model.

MATERIALS AND METHODS

Twenty-seven pigs were divided into 3 cohorts. In Cohort I, 16 pigs were randomized to receive (n = 4 each) 40-100-μm microspheres in 1 or 2 fundal arteries, 70-340-μm radiopaque microspheres in 2 fundal arteries, or saline. In Cohort II, 3 pigs underwent renal arterial embolization with either custom-made 100-200-μm, 200-250-μm, 200-300-μm, or 300-400-μm radiopaque microspheres or Bead Block 300-500 μm with microsphere distribution assessed histologically. In Cohort III, 8 pigs underwent BAE in 2 fundal arteries with tailored 100-200-μm radiopaque microspheres (n = 5) or saline (n = 3).

RESULTS

In Cohort I, no significant differences in weight or ghrelin expression were observed between BAE and control animals. Moderate-to-severe gastric ulcerations were noted in all BAE animals. In Cohort II, renal embolization with 100-200-μm microspheres occluded vessels with a mean diameter of 139 μm ± 31, which is within the lower range of actual diameters of Bead Block 300-500 μm. In Cohort III, BAE with 100-200-μm microspheres resulted in significantly lower weight gain (42.3% ± 5.7% vs 51.6% ± 2.9% at 8 weeks; P = .04), fundal ghrelin cell density (16.1 ± 6.7 vs 23.6 ± 12.6; P = .045), and plasma ghrelin levels (1,709 pg/mL ± 172 vs 4,343 pg/mL ± 1,555; P < .01) compared with controls and superficial gastric ulcers (5/5).

CONCLUSIONS

In this preclinical model, tailored 100-200-μm microspheres were shown to be most suitable for BAE in terms of safety and efficacy.

Interventional metabology: A review of bariatric arterial embolization and endovascular denervation for treating metabolic disorders

The rising prevalence of metabolic disorders such as obesity and type 2 diabetes mellitus (T2DM) poses a major challenge to global health. Existing therapeutic approaches have limitations, and there is a need for new, safe, and less invasive treatments. Interventional metabolic therapy is a new addition to the treatment arsenal for metabolic disorders. This review focuses on two interventional techniques: bariatric arterial embolization (BAE) and endovascular denervation (EDN). BAE involves embolizing specific arteries feeding ghrelin-producing cells to suppress appetite and promote weight loss. EDN targets nerves that regulate metabolic organs to improve glycemic control in T2DM patients. We describe the current state of these techniques, their mechanisms of action, and the available safety and effectiveness data. We also propose a new territory called "Interventional Metabology" to encompass these and other interventional approaches to treating metabolic disorders.

Photodynamic Methylene Blue-Embedded Intragastric Satiety-Inducing Device to Treat Obesity

Bariatric surgery is the most effective treatment for weight recidivism, and endoscopic bariatric treatment has been developed for a similar effect without anatomical modification. An intragastric satiety-inducing device (ISD) is a minimally invasive approach to induce satiety by continuously pressing the stomach and stimulating ghrelin-producing cells. To enhance the therapeutic effects of ISD, photodynamic therapy (PDT) can be combined by generating singlet oxygen under laser irradiation. Methylene blue (MB), as a photosensitizer (PS), was coated on the ISD surface for singlet oxygen production to stimulate or destroy cells. Ghrelin-producing cells effectively inhibited ghrelin secretion and induced gastrointestinal satiety signals compared with the MB-uncoated device via PDT. Herein, MB-embedded ISDs were developed, and their photoresponsive abilities were demonstrated in the device itself and in vitro. PDT with an MB-embedded ISD was successfully performed in a porcine model, which had 2-fold reduced body weight gain (12% in PDT vs 24% in control) and 2-fold reduced ghrelin levels (21.2 pg/mL in PDT vs 45.1 pg/mL in control) at the first week postprocedure. The simple and unique operation extends the point of view in PDT and is expected to be a novel endoscopic bariatric therapy.

Weight Loss and Gastrointestinal Hormone Variation Caused by Gastric Artery Embolization: An Updated Analysis Study

OBJECTIVE

Many gastric artery embolizations (GAE) have been performed in recent years. We try to determine whether GAE caused weight loss by decreasing gastrointestinal hormone through the analysis of weight loss and gastrointestinal hormones changes.

METHODS

The PubMed and Medline databases, and the Cochrane Library, were searched using the following keywords. A total of 10 animal trials (n=144), 15 human trials (n=270) were included for analysis. After GAE, we mainly evaluated the changes in body weight loss (BWL) and body mass index (BMI), as well as metabolic indexes, such as blood glucose, lipids, and gastrointestinal hormones levels.

RESULTS

Animal subjects received either chemical or particle embolization, while human subjects only received particle embolization. In animal trials (growing period), the GAE group gained weight significantly slower than the sham-operated group, ghrelin levels decreased. In human trials, GAE brought more weight loss in the early stages, with a trend towards weight recovery after several months that was still lower than baseline levels. Besides weight loss, abnormal metabolic indicators, such as blood glucose and lipids were modified, and the quality of life (QOL) scores of obese patients improved. In addition, weight loss positively correlates with ghrelin.

CONCLUSION

GAE may help people lose weight and become a new minimally invasive and effective surgery for the treatment of modest obesity. Physiologic changes in gastrointestinal tract of gastrointestinal hormones level may be one reason for weight loss in GAE.

Left gastric artery embolization for obesity treatment: a systematic review and meta-analysis of human and animal studies

PURPOSE

The main purpose of this systematic review was to reflect on recent literature on bariatric LGA embolization for obesity treatment and to compare this new procedure in human and animal studies.

METHODS

A systematic search of Scopus, MEDLINE, Web of Science, Embase, and Google Scholar was performed to identify human and animal studies employing bariatric LGA embolization to treat obesity. As well, Cochrane's Q test and the I² statistic were utilized to determine heterogeneity.

RESULTS

Nine human and four animal studies recruiting a total of 118 cases (n = 78 patients and n = 40 animals) were included in analysis. All assessments on body mass index (BMI), weight, and ghrelin levels had been fulfilled based on before-after (human studies) and intervention-control designs (animal studies) using bariatric LGA embolization. The findings suggested that bariatric LGA embolization had significantly decreased BMI (mean difference (MD): - 2.66, 95% confidence interval [CI] - 3.74, - 1.58, P < 0.001) and weight (MD: - 8.69, 95% CI - 10.48, - 6.89, P < 0.001) in humans. Although overall pooled estimate showed no significant changes in ghrelin levels following this procedure (Hedges' g statistic: - 0.91, 95% CI - 1.83, 0.01, P = 0.05) in humans, a significant reduction was observed in animal studies (MD: - 756.56, 95% CI - 1098.79, - 414.33, P < 0.001) along with a significant drop in weight (MD: - 7.64, 95% CI - 13.73, - 1.54, P < 0.001).

CONCLUSION

The present study concluded that ghrelin levels in humans had not been affected, although bariatric LGA embolization might significantly improve BMI and weight.

Interventional Radiology Obesity Therapeutics: Proceedings from the Society of Interventional Radiology Foundation Research Consensus Panel

The Society of Interventional Radiology Foundation commissioned a Research Consensus Panel to establish a research agenda on "Obesity Therapeutics" in interventional radiology (IR). The meeting convened a multidisciplinary group of physicians and scientists with expertise in obesity therapeutics. The meeting was intended to review current evidence on obesity therapies, familiarize attendees with the regulatory evaluation process, and identify research deficiencies in IR bariatric interventions, with the goal of prioritizing future high-quality research that would move the field forward. The panelists agreed that a weight loss of >8%-10% from baseline at 6-12 months is a desirable therapeutic endpoint for future IR weight loss therapies. The final consensus on the highest priority research was to design a blinded randomized controlled trial of IR weight loss interventions versus sham control arms, with patients receiving behavioral therapy.

Endovascular Bariatric Surgery as Novel Minimally Invasive Technique for Weight Management in the Morbidly Obese: Review of the Literature

Nowadays, obesity represents one of the most unresolved global pandemics, posing a critical health issue in developed countries. According to the World Health Organization, its prevalence has tripled since 1975, reaching a prevalence of 13% of the world population in 2016. Indeed, as obesity increases worldwide, novel strategies to fight this condition are of the utmost importance to reduce obese-related morbidity and overall mortality related to its complications. Early experimental and initial clinical data have suggested that endovascular bariatric surgery (EBS) may be a promising technique to reduce weight and hormonal imbalance in the obese population. Compared to open bariatric surgery and minimally invasive surgery (MIS), EBS is much less invasive, well tolerated, with a shorter recovery time, and is probably cost-saving. However, there are still several technical aspects to investigate before EBS can be routinely offered to all obese patients. Further prospective studies and eventually a randomized trial comparing open bariatric surgery vs. EBS are needed, powered for clinically relevant outcomes, and with adequate follow-up. Yet, EBS may already appear as an appealing alternative treatment for weight management and cardiovascular prevention in morbidly obese patients at high surgical risk.

Bariatric Arterial Embolization with Calibrated Radiopaque Microspheres and an Antireflux Catheter Suppresses Weight Gain and Appetite-Stimulating Hormones in Swine

PURPOSE

To examine safety and efficacy of bariatric arterial embolization (BAE) with x-ray-visible embolic microspheres (XEMs) and an antireflux catheter in swine.

MATERIAL AND METHODS

BAE with selective infusion of XEMs (n = 6) or saline (n = 4, control) into gastric fundal arteries was performed under x-ray guidance. Weight and plasma hormone levels were measured at baseline and weekly for 4 weeks after embolization. Cone-beam CT images were acquired immediately after embolization and weekly for 4 weeks. Hormone-expressing cells in the stomach were assessed by immunohistochemical staining.

RESULTS

BAE pigs lost weight 1 week after embolization followed by significantly impaired weight gain relative to control animals (14.3% vs 20.9% at 4 weeks, P = .03). Plasma ghrelin levels were significantly lower in BAE pigs than in control animals (1,221.6 pg/mL vs 1,706.2 pg/mL at 4 weeks, P < .01). XEMs were visible on x-ray and cone-beam CT during embolization, and radiopacity persisted over 4 weeks (165.5 HU at week 1 vs 158.5 HU at week 4, P = .9). Superficial mucosal ulcerations were noted in 1 of 6 BAE animals. Ghrelin-expressing cell counts were significantly lower in the gastric fundus (17.7 vs 36.8, P < .00001) and antrum (24.2 vs 46.3, P < .0001) of BAE pigs compared with control animals. Gastrin-expressing cell counts were markedly reduced in BAE pigs relative to control animals (98.5 vs 127.0, P < .02). Trichrome staining demonstrated significantly more fibrosis in BAE animals compared with control animals (13.8% vs 8.7%, P < .0001).

CONCLUSIONS

XEMs enabled direct visualization of embolic material during and after embolization. BAE with XEMs and antireflux microcatheters was safe and effective.

Future of Bariatric Embolization: A Review of Up-to-date Clinical Trials

Obesity is a significant health issue with an overall rise in mortality; it has multiple risk factors, including hormonal effects, which play a significant role in the balance of food intake and weight gain. Ghrelin is an anabolic hormone secreted from stomach fundus and plays a significant role in this regulation. Management of obesity involves multiple interventions, including lifestyle adjustment, pharmacotherapy, and bariatric surgery. Bariatric embolization is a relatively new procedure; several animal studies show that embolization of the left gastric artery reduces serum ghrelin and induces weight loss.  Also, several clinical studies were conducted in the past ten years which have shown bariatric embolization's effectiveness in inducing weight loss: a meta-analysis of 47 patients included in six different clinical studies of left gastric artery embolization resulted in 8% total weight loss from baseline body weight. Many studies also show this procedure's effect on lowering the HgA1C level and lipid profile. Clinical studies mostly reported minor adverse effects such as transient abdominal discomfort, nausea and vomiting, gastric ulcers, and major adverse effects were uncommon, suggesting the procedure is well tolerated. It may be an alternative line of management in patients who are not suitable candidates for bariatric surgery. Although future clinical studies will provide an answer to several questions like the exact effects of the procedure on diabetes and metabolic syndrome, future studies are also needed to establish particular guidelines to match different patient characteristics with their optimal procedural techniques and pre- and post-procedure evaluation tests.

Anatomical and Technical Considerations for Bariatric Embolization

Obesity is a well-known major public health concern associated with significant morbidity and mortality. Bariatric arterial embolization (BAE) is a minimally invasive, image-guided therapy that targets hormones linked to obesity by defunctionalizing specific portions of the stomach with the delivery of embolics. The goal of BAE is to induce weight loss through a reduction of appetite-mediating hormones with transarterial embolization of the gastric fundus. This article will review the anatomical and technical considerations for successful BAE.

Rationale and Preclinical Data Supporting Bariatric Arterial Embolization

The prevalence of obesity is increasing globally, leading to significantly increased morbidity, mortality, and health care costs. However, there is a lack of effective treatment options that can treat patients with obesity less invasively than with bariatric surgery. Bariatric arterial embolization (BAE) is an image-guided, minimally invasive, percutaneous procedure that is currently being investigated in preclinical animal models and early clinical trials. If successful, BAE may represent a viable interventional approach for obesity treatment. The purpose of this article is to introduce the physiological and anatomical rationale for BAE, review techniques involved in performing BAE for weight modulation, and provide up-to-date preclinical evidence that supports the translation of BAE into patients.

Effects of Left Gastric Artery Ligation Versus Sleeve Gastrectomy on Obesity-Induced Adipose Tissue Macrophage Infiltration and Inflammation in Diet-Induced Obese Rats

Background

Bariatric procedures such as left gastric artery ligation (LGAL) and sleeve gastrectomy (SG) have emerged as important procedures for treating morbid obesity. In this study, we compared the effects of LGAL vs. SG on obesity-induced adipose tissue macrophage infiltration and inflammation in diet-induced obese rats.

Material/Methods

Sprague-Dawley (SD) rats were fed a high-fat diet (HFD) for 16 weeks to induce obesity. SG, GLAL, or corresponding sham surgeries were performed in anesthetized rats. Inflammatory factor expression in serum and epididymal and retroperitoneal adipose tissues were analyzed 4 weeks after surgery. Macrophage infiltration and phenotype transformation were also assessed with Western blot analysis and immunofluorescence.

Results

Both LGAL and SG strongly attenuated high-fat diet (HFD)-induced fat accumulation in retroperitoneal and epididymal tissues. The expressions of inflammatory cytokines such as tumor necrosis factor (TNF)-agr;, interleukin (IL)-6, and monocyte chemoattractant protein (MCP)-1 were downregulated after LGAL and after SG by promoting activation of M2 macrophages, despite continued exposure to HFD. Furthermore, both LGAL and SG resulted in increased macrophage infiltration, but did not contribute to phenotype transformation of macrophages to M1.

Conclusions

LGAL and SG both reduced fat accumulation caused by HFD feeding. Therapies designed to ameliorate the inflammatory response by promoting activation of M2 macrophages may be valuable.

Body composition changes after left gastric artery embolization in overweight and obese individuals

PURPOSE

To determine the effects of left gastric artery embolization (LGAE) on computed tomography (CT) body composition change.

MATERIALS AND METHODS

Sixteen overweight or obese patients who had abdominal CT scans before and after LGAE for gastric bleeding were retrospectively reviewed. Body composition analysis was performed with semiautomated imaging processing algorithms (MATLAB 13.0, Math Works, MA). Adipose tissue and lean skeletal muscle were measured using threshold attenuation values. Total body fat index (BFI), subcutaneous fat index (SFI), visceral fat index (VFI), intramuscular fat index (IMFI), and skeletal muscle index (SMI) were determined ([tissue area (cm)]²/[height (m)]²). Excess body weight (EBW) was determined based on the Lorentz formula for ideal body weight.

RESULTS

Mean follow-up was 1.5 ± 0.8 months. Following LGAE, patients experienced significantly decreased body weight (p = 0.003), BMI (p = 0.005), EBW (p = 0.003), BFI (p = 0.03), SFI (p = 0.03), and SMI (p < 0.001). Changes in VFI and IMFI did not significantly change (p = 0.13 and p = 0.83, respectively).

CONCLUSIONS

Patients who underwent LGAE had significant unintended weight loss as a result of decreased body fat and skeletal muscle. Body composition analysis can readily assess the extent of fat loss and identify muscle wasting.

Gastrointestinal Hormones Manipulation to Counteract Metabolic Syndrome Using Duodenal Targeted Embolization

PURPOSE

Targeted embolization of gastrointestinal (GI) arteries can modify hormonal production. We aimed to evaluate the impact of the embolization of the gastroduodenal artery (GDA) on the activity of foregut mucosa.

METHODS

The GDA's duodenal branch was embolized in 12 Yucatan pigs using 100-300 µm (group A; n = 4) or 300-500 µm (group B; n = 4) microspheres, followed by coiling of the branch. In 4 animals (sham), only saline was injected. The levels of GI hormones (ghrelin, glucose-dependent insulinotropic peptide [GIP], glucagon-like peptide-1 [GLP-1], insulin, peptide YY [PYY], leptin) and the gene expression of sodium-glucose-linked transporter-1 (SGLT-1) and glucose transporter-2 (GLUT-2) were assessed before (T0), 1 hour (T1), 1 month (T2), 3 months (T3), and 6 months (T4) after embolization.

RESULTS

In group A, a segmental duodenal stenosis occurred in all cases, which required balloon dilatation. There was a significant drop in the baseline glycemia in group A at T1 and T4 versus sham. Ghrelin was reduced in group A versus baseline and versus group B at T2 and T3 and versus sham at T1 and T3. Insulin was significantly lower in group A versus B at T1 and at T4 but not versus sham. SGLT-1 expression increased in B and sham at T4, while it remained stable in group A. GLUT-2 expression increased in sham at T4 but not in A or B.

CONCLUSIONS

GDA embolization induced a decrease in ghrelin production and influenced expression of glucose carriers in the foregut mucosa.

Bariatric Embolization of Arteries for the Treatment of Obesity (BEAT Obesity) Trial: Results at 1 Year

Background Bariatric embolization is a new endovascular procedure to treat patients with obesity. However, the safety and efficacy of bariatric embolization are unknown. Purpose To evaluate the safety and efficacy of bariatric embolization in severely obese adults at up to 12 months after the procedure. Materials and Methods For this prospective study (NCT0216512 on ClinicalTrials.gov ), 20 participants (16 women) aged 27-68 years (mean ± standard deviation, 44 years ± 11) with mean body mass index of 45 ± 4.1 were enrolled at two institutions from June 2014 to February 2018. Transarterial embolization of the gastric fundus was performed using 300- to 500-µm embolic microspheres. Primary end points were 30-day adverse events and weight loss at up to 12 months. Secondary end points at up to 12 months included technical feasibility, health-related quality of life (Short Form-36 Health Survey ([SF-36]), impact of weight on quality of life (IWQOL-Lite), and hunger or appetite using a visual assessment scale. Analysis of outcomes was performed by using one-sample t tests and other exploratory statistics. Results Bariatric embolization was performed successfully for all participants with no major adverse events. Eight participants had a total of 11 minor adverse events. Mean excess weight loss was 8.2% (95% confidence interval [CI]: 6.3%, 10%; P < .001) at 1 month, 11.5% (95% CI: 8.7%, 14%; P < .001) at 3 months, 12.8% (95% CI: 8.3%, 17%; P < .001) at 6 months, and 11.5% (95% CI: 6.8%, 16%; P < .001) at 12 months. From baseline to 12 months, mean SF-36 scores increased (mental component summary, from 46 ± 11 to 50 ± 10, P = .44; physical component summary, from 46 ± 8.0 to 50 ± 9.3, P = .15) and mean IWQOL-Lite scores increased from 57 ± 18 to 77 ± 18 (P < .001). Hunger or appetite decreased for 4 weeks after embolization and increased thereafter, without reaching pre-embolization levels. Conclusion Bariatric embolization is well tolerated in severely obese adults, inducing appetite suppression and weight loss for up to 12 months. Published under a CC BY-NC-ND 4.0 license. Online supplemental material is available for this article.

Transradial left gastric artery embolization to treat severe obesity: A pilot study

BACKGROUND

Bariatric surgery is currently the only effective treatment with long-lasting results to treat severe obesity.

OBJECTIVES

We performed a pilot study to evaluate the feasibility, safety and efficacy of percutaneous distal embolization of the left gastric artery (LGA) using a transradial approach.

METHODS AND RESULTS

We recruited seven severely obese male patients (mean age 48 ± 7 years) referred for diagnostic coronary angiography. Mean baseline weight was 160 ± 27 kg and body mass index was of 52 ± 8 kg/m2 . We successfully injected 300-500 μm polyvinyl alcohol particles using 5Fr catheters and all distal LGA were occluded at the end of procedures. Mean procedure duration was 24 ± 13 min and mean fluoroscopy time was 10 ± 5 min. Six patients reported mild transient epigastric discomfort, which resolved with proton pump inhibitors. At 2 months, the average weight loss was of 7 ± 6 kg (median loss: -10 kg [-2, -11]), 6 ± 12 kg (median loss: -9 kg [-16, +4]) at 6 months and 13 ± 17 kg (median loss: -11 kg [0, -25]) up to 12 months after index procedures.

CONCLUSION

Percutaneous transradial LGA embolization appears to be a promising technique to reduce the obesity burden. Randomized trials are required to further delineate the risk/benefit ratio, potential clinical indications and long term results.

Future of IR: Emerging Techniques, Looking to the Future…and Learning from the Past

Innovation has been the cornerstone of interventional radiology since the early years of the founders, with a multitude of new therapeutic approaches developed over the last 50 years. What is the future holding for us? This article presents an overview of the in-coming developments that are catching on at this moment, particularly focusing on three items: the new applications of existing techniques, particularly embolotherapy and interventional oncology; the cutting-edge devices; the imaging technologies at the forefront of the image-guidance. Besides this, clinical vision and patient relation remain crucial for the future of the discipline.

Bariatric Arterial Embolization for Obesity: A Review of Early Clinical Evidence

Obesity is a worldwide public health epidemic that leads to increased morbidity, mortality, and cost burden to health care. Although bariatric surgery has been recognized as a standard invasive treatment for obesity, it is accompanied by relatively high morbidity and cost burden, as well as limited treatment outcome. Therefore, alternative treatments with lower morbidity and cost for surgery that target patients who are obese, but not morbidly obese, are needed. A minimally invasive trans-catheter procedure, named bariatric arterial embolization or bariatric embolization (BAE), has been identified as a potential solution, based on its safety and preliminary efficacy profiles. The purpose of this review is to introduce up-to-date clinical data and discuss future directions for BAE for the treatment of obesity.

Analysis of weight changes after left gastric artery embolization in a cancer-naive population

PURPOSE

We aimed to evaluate weight changes after left gastric artery (LGA) embolization in a retrospective cancer-naive cohort.

METHODS

A retrospective study was conducted to identify patients who underwent LGA embolization for gastrointestinal bleeding (GI). Patients with known cancer diagnoses at the time of LGA embolization were excluded. Pre- and postprocedure weights were assessed. Statistical analysis was performed using paired t-test and Wilcoxon signed-rank test.

RESULTS

A total of 39 patients were identified. In 21 patients who had documented pre- and postprocedural weights, a median of 16.3 kg weight loss (P = 0.045) was observed over a median time of 12 months (range, 2-72). In patients who had pre- and postprocedure endoscopies (n=6), 2 had worsening ulcers following LGA embolization and 4 had stable or no abnormal findings.

CONCLUSION

Our preliminary observation suggests that LGA embolization is well tolerated and results in unintended weight loss. Larger studies are needed to confirm these preliminary findings.

Bariatric Arterial Embolization: Effect of Microsphere Size on the Suppression of Fundal Ghrelin Expression and Weight Change in a Swine Model

Purpose To determine whether microsphere size effects ghrelin expression and weight gain after selective bariatric arterial embolization (BAE) in swine. Materials and Methods BAE was performed in 10 swine by using smaller (100-300 μm; n = 5) or larger (300-500 μm; n = 5) calibrated microspheres into gastric arteries. Nine control pigs underwent a sham procedure. Weight and fasting plasma ghrelin levels were measured at baseline and weekly for 16 weeks. Ghrelin-expressing cells (GECs) in the stomach were assessed by using immunohistochemical staining and analyzed by using the Wilcoxon rank-sum test. Results In pigs treated with smaller microspheres, mean weight gain at 16 weeks (106.9% ± 15.0) was less than in control pigs (131.9% ± 11.6) (P < .001). Mean GEC density was lower in the gastric fundus (14.8 ± 6.3 vs 25.0 ± 6.9, P < .001) and body (27.5 ± 12.3 vs 37.9 ± 11.8, P = .004) but was not significantly different in the gastric antrum (28.2 ± 16.3 vs 24.3 ± 11.6, P = .84) and duodenum (9.2 ± 3.8 vs 8.7 ± 2.9, P = .66) versus in control pigs. BAE with larger microspheres failed to suppress weight gain or GECs in any stomach part compared with results in control swine. Plasma ghrelin levels were similar between BAE pigs and control pigs, regardless of microsphere size. Week 1 endoscopic evaluation for gastric ulcers revealed none in control pigs, five ulcers in five pigs embolized by using smaller microspheres, and three ulcers in five pigs embolized by using larger microspheres. Conclusion In bariatric arterial embolization, smaller microspheres rather than larger microspheres showed greater weight gain suppression and fundal ghrelin expression with more gastric ulceration in a swine model. © RSNA, 2018.

Physiological and metabolic control of diet selection

The fact that most farm animals have no dietary choice under commercial practices translates the dietary decisions to the carers. Thus, a lack of understanding of the principles of dietary choices is likely to result in a high toll for the feed industry. In healthy animals, diet selection and, ultimately, feed intake is the result of factoring together the preference for the feed available with the motivation to eat. Both are dynamic states and integrate transient stimulus derived from the nutritional status, environmental and social determinants of the animal with hard-wired genetic mechanisms. Peripheral senses are the primary inputs that determine feed preferences. Some of the sensory aspects of feed, such as taste, are innate and genetically driven, keeping the hedonic value of feed strictly associated with a nutritional frame. Sweet, umami and fat tastes are all highly appetitive. They stimulate reward responses from the brain and reinforce dietary choices related to essential nutrients. In contrast, aroma (smell) recognition is a plastic trait and preferences are driven mostly by learned experience. Maternal transfer through perinatal conditioning and the individual’s own innate behaviour to try or to avoid novel feed (often termed as neophobia) are known mechanisms where the learning process strongly affects preferences. In addtition, the motivation to eat responds to episodic events fluctuating in harmony with the eating patterns. These signals are driven mainly by gastrointestinal hormones (such as cholecystokinin [CCK] and glucagon-like peptide 1 [GLP-1]) and load. In addition, long-term events generate mechanisms for a sustainable nutritional homeostasis managed by tonic signals from tissue stores (i.e. leptin and insulin). Insulin and leptin are known to affect appetite by modulating peripheral sensory inputs. The study of chemosensory mechanisms related to the nutritional status of the animal offers novel tools to understand the dynamic states of feed choices so as to meet nutritional and hedonic needs. Finally, a significant body of literature exists regarding appetite driven by energy and amino acids in farm animals. However, it is surprising that there is scarcity of knowledge regarding what and how specific dietary nutrients may affect satiety. Thus, a better understanding on how bitter compounds and excess dietary nutrients (i.e. amino acids) play a role in no-choice animal feeding is an urgent topic to be addressed so that right choices can be made on the animal’s behalf.

Bariatric Embolization of the Left Gastric Arteries for the Treatment of Obesity: 9-Month Data in 5 Patients

PURPOSE

The purpose of this study is to investigate the safety and 9-month effectiveness of transcatheter left gastric artery embolization (LGAE) for treating patients with obesity.

MATERIALS AND METHODS

The protocol of this study was approved by the Institutional Ethics Review Board. Five obese patients (3 men and 2 women) with mean weight of 102.0 ± 16.19 kg (range, 82.1-125.5 kg) and mean body mass index (BMI) of 38.1 kg/m² ± 3.8 (range, 32.9-42.4 kg/m²) underwent LGAE with polyvinyl alcohol (PVA) particles in diameter of 500-710 μm. The primary endpoint was the safety by grading the adverse events (AEs) according to the Common Terminology Criteria for Adverse Events (CTCAE v4.0) within 30 days after LGAE. The secondary endpoints were measured with serum ghrelin and leptin levels, body weight, waist circumference, waist-to-height ratio, and abdominal fat quantity on MRI at the day immediately before LGAE and every 3 months after LGAE.

RESULTS

LGAE was successfully performed in all patients. A superficial linear ulceration below the cardia was seen in 1 patient 3 days after LGAE and healed within 30 days. No other serious AEs (grade III or above) occurred. Average body weight loss at 3, 6, and 9 months was 8.28 ± 7.3 kg (p = 0.074), 10.42 ± 8.21 kg (p = 0.047), and 12.9 ± 14.66 kg (p = 0.121), respectively. The level of serum ghrelin decreased by 40.83% (p = 0.009), 31.94% (p = 0.107), and 24.82% (p = 0.151) at 3, 6, and 9 months after LGAE, respectively. There was minimal reduction of leptin levels at 3 and 6 months following LGAE (decreased by 0.26%, p = 0.929, and 4.33%, p = 0.427, respectively), but it declined obviously 9 months after LGAE (decreased by 11.22%, p = 0.295). Both waist circumference and waist-to-height ratio decreased after LGAE. MRI showed the area of subcutaneous adipose tissue decreased from the baseline of 400.90 ± 79.25 to 320.36 ± 68.06 cm² (decreased by 20.09%, p = 0.006) at 3 months, to 328.31 ± 52.67 cm² (decreased by 18.11%, p = 0.020) at 6 months, and to 286.40 ± 55.72 cm² (decreased by 28.52%, p = 0.101) at 9 months after LGAE, respectively. But the decrease of abdominal fat loss at 9 months after LGAE was largely due to the reduction in visceral adipose tissue.

CONCLUSIONS

Our study with 9-month data in 5 patients indicates that bariatric embolization of the LGA is a safe and may be a promising strategy to suppress the production of ghrelin and results in weight loss and abdominal fat reduction.

TRIAL REGISTRATION

ClinicalTrials.gov (NCT02786108).

Current and cutting-edge interventions for the treatment of obese patients

The number of people classified as obese, defined by the World Health Organization as having a body mass index ≥30, has been rising since the 1980s. Obesity is associated with comorbidities such as hypertension, diabetes mellitus, and nonalcoholic fatty liver disease. The current treatment paradigm emphasizes lifestyle modifications, including diet and exercise; however this approach produces only modest weight loss for many patients. When lifestyle modifications fail, the current "gold standard" therapy for obesity is bariatric surgery, including Roux-en-Y gastric bypass, sleeve gastrectomy, duodenal switch, and placement of an adjustable gastric band. Though effective, bariatric surgery can have severe short- and long-term complications. To fill the major gap in invasiveness between lifestyle modification and surgery, researchers have been developing pharmacotherapies and minimally invasive endoscopic techniques to treat obesity. Recently, interventional radiologists developed a percutaneous transarterial catheter-directed therapy targeting the hormonal function of the stomach. This review describes the current standard obesity treatments (including diet, exercise, and surgery), as well as newer endoscopic bariatric procedures and pharmacotherapies to help patients lose weight. We present data from two ongoing human trials of a new interventional radiology procedure for weight loss, bariatric embolization.

Clinical Safety of Bariatric Arterial Embolization: Preliminary Results of the BEAT Obesity Trial

Purpose To conduct a pilot prospective clinical trial to evaluate the feasibility, safety, and short-term efficacy of bariatric embolization, a recently developed endovascular procedure for the treatment of obesity, in patients with severe obesity. Materials and Methods This is an institutional review board- and U.S. Food and Drug Administration-approved prospective physician-initiated investigational device exemption study. This phase of the study ran from June 2, 2014, to August 4, 2015. Five severely obese patients (four women, one man) who were 31-49 years of age and who had a mean body mass index of 43.8 kg/m2 ± 2.9 with no clinically important comorbidities were enrolled in this study. Transarterial embolization of the gastric fundus with fluoroscopic guidance was performed with 300-500-μm Embosphere microspheres. The primary end point was 30-day adverse events (AEs). The secondary end points included short-term weight loss, serum obesity-related hormone levels, hunger and satiety assessments, and quality of life (QOL) surveys, reported up to 3 months. Simple statistics of central tendencies and variability were calculated. No hypothesis testing was performed. Results The left gastric artery, with or without the gastroepiploic artery, was embolized in five patients, with a technical success rate of 100%. There were no major AEs. There were two minor AEs-subclinical pancreatitis and a mucosal ulcer that had healed by the time of 3-month endoscopy. A hospital stay of less than 48 hours for routine supportive care was provided for three patients. Mean excess weight loss of 5.9% ± 2.4 and 9.0% ± 4.1 was noted at 1 month and at 3 months, respectively. Mean change in serum ghrelin was 8.7% ± 34.7 and -17.5% ± 29 at 1 month and 3 months, respectively. Mean changes in serum glucagon-like peptide 1 and peptide YY were 106.6% ± 208.5 and 17.8% ± 54.8 at 1 month. There was a trend toward improvement in QOL parameters. Hunger/appetite scores decreased in the first 2 weeks after the procedure and then rose without reaching preprocedure levels. Conclusion Bariatric embolization is feasible and appears to be well tolerated in severely obese patients. In this small patient cohort, it appears to induce appetite suppression and may induce weight loss. Further expansion of this study will provide more insight into the long-term safety and efficacy of bariatric embolization. © RSNA, 2017 Online supplemental material is available for this article.

Bariatric Arterial Embolization with Non-spherical Polyvinyl Alcohol Particles for Ghrelin Suppression in a Swine Model

PURPOSE

To evaluate the effect of bariatric arterial embolization (BAE) with non-spherical polyvinyl alcohol (PVA) particles on systemic ghrelin levels, weight change, and gastric ulceration risk in a swine model.

MATERIALS AND METHODS

From March 2014 to February 2015, ten healthy swine were used in the study (mean weight 31.5 kg; range 24.0-41.5 kg). The animals were randomly assigned to two groups: the embolized group (n = 5) in which BAE was performed and the control group (n = 5). In the embolized group, BAE was performed by selectively infusing 150-250 or 50-150 μm PVA into the gastric arteries that supplied the fundus of the stomach. In the control group, a sham procedure was performed with saline infusion. Plasma ghrelin levels were prospectively obtained at baseline and every 2 weeks thereafter. Endoscopy was performed 3 weeks after BAE to see whether any gastric ulcer occurred. To determine the durability of the occluded arteries, repeated celiac trunk angiography was performed 8 weeks after BAE. Then, all the swine were killed and necropsies were performed.

RESULTS

The mean post-procedure ghrelin value decreased by 370.0 pg/mL in the embolized group at week 3 (mean 536.0 ± 334.3 pg/mL) and week 5 (mean 515.0 ± 150.0 pg/mL, p < 0.05) relative to baseline (880.0 ± 559.5 pg/mL), respectively, but ghrelin levels were not significantly decreased between the embolized and control groups. There was a significant body weight change as follows: 35.1 ± 9.5 to 46.6 ± 15.7 kg and 31.8 ± 5.8 to 41.2 ± 6.6 kg at baseline and endpoint in the control and embolized groups, respectively (p < 0.05). However, the difference between groups was not significant at endpoint. In the embolized group, ulcerations were identified in three animals (60%) and the recanalization of the embolized arteries was noted on follow-up angiography in three animals (60%), respectively.

CONCLUSION

BAE with PVA particles can transiently suppress ghrelin levels in embolized animals, but levels are not significantly different compared to controls. Stomach ulcerations were identified in 60% of the embolized animals.

Bariatric embolization: a new and effective option for the obese patient?

Obesity is a public health epidemic in the United States, which results in significant morbidity, mortality, and cost to the healthcare system. Despite advancements in traditional therapeutic options for the obese patients, there is a treatment gap for patients in whom lifestyle modifications alone have not been successful, but for whom bariatric surgery is not a suitable option. Areas covered: This treatment gap needs to be addressed and thus, complimentary or alternative treatments to lifestyle changes and surgery are urgently needed. Recent evidence suggests that embolization of the gastric fundus ('Bariatric Embolization'), which is predominantly supplied by the left gastric artery, may affect energy homeostasis by decreasing ghrelin production. The purpose of this special report is to discuss the background, rationale and latest data on this topic, as well as provide the latest data from the ongoing BEAT Obesity clinical trial. Expert commentary: A multipronged approach is essential in the treatment of obesity. Bariatric embolization looks to treat the hormonal imbalances which contribute to obesity. If proven successful in the long-term, bariatric embolization represents a potential minimally invasive approach to treat obesity offered by interventional radiologists.

Comparison of Weight Loss, Ghrelin, and Leptin Hormones After Ligation of Left Gastric Artery and Sleeve Gastrectomy in a Rat Model

Background

Ligation of the left gastric artery (LLGA), which supplies the fundus of the stomach, may reduce the appetite hormone ghrelin, resulting in weight control. The aim of this study was to compare LLGA and sleeve gastrectomy (SG) in terms of postoperative outcomes in a rat model.

Material/Methods

Fifteen male Wistar albino rats, weighing >350 grams (range 350–525 grams), were enrolled in LLGA (N=5), SG (N=5), and control (N=5) groups. Blood samples were drawn preoperatively and also during the first and fourth week postoperatively to assay ghrelin and leptin hormone levels. Body weight was measured in each group.

Results

The maximum reduction in ghrelin level (41.5%) was found in the LLGA group. Considerable% total weight loss (TWL) (mean 24.1%) was observed in the SG group, and slight%TWL was noted in the control and LLGA groups (means of 0.1% and 2.1%, respectively). There was no significant difference in mean percent weight change between the LLGA and the SG groups (p=0.08). Blood sample analysis revealed no statistically significant changes in ghrelin or leptin levels between the groups (p=0.9 and p=0.3, respectively).

Conclusions

We present evidence that LLGA causes the same reduction in ghrelin hormone levels as SG at 4 weeks after surgery in a rat model. However, LLGA did not cause the same%TWL as SG. The mechanism of weight loss in SG is most likely due to restriction and to the effects of the procedure, rather than due to neurohormonal changes.

Bariatric manipulation of gastric arteries: A systematic review on the potential concept for treatment of obesity

BACKGROUND

Gastric artery embolization (GAE) has recently received attention as a minimally invasive intervention in bariatric setting.

AIMS

The current systematic review aimed to gather and categorizes the existing data in the literature regarding bariatric gastric artery manipulation. This will highlight the importance of this potential concept as a therapeutic modality.

METHODS

A PubMed/Medline search was conducted to identify animal and human studies investigating the effect of gastric artery manipulation on weight, ghrelin, obesity, and tissue adiposity.

RESULTS

A total of 9 studies including 6 animal experiments with 71 subjects and 3 human studies with a total of 25 patients were retrieved. Animal subjects underwent chemical embolization while particle embolization was only used in human subjects. Five animal studies and 1 human study reported decreased ghrelin concentration. Three animal experiments and 2 human studies showed a significant weight change following GAE. There was no report regarding a serious adverse event requiring surgical or interventional management.

CONCLUSION

Currently, data regarding the potential role of gastric artery manipulation in decreasing the ghrelin and potential weight loss is scarce.

Bariatric Embolization: Pilot Study on the Impact of Gastroprotective Agents and Arterial Distribution on Ulceration Risk and Efficacy in a Porcine Model

PURPOSE

To assess whether the number of fundal arteries embolized and use of gastroprotective agents have an impact on ghrelin suppression and gastric ulceration rates.

MATERIALS AND METHODS

Twenty-two healthy, growing swine (mean, 38.4 kg; range, 30.3-47.0 kg) were evaluated. Six control swine underwent a sham procedure. Gastric embolization was performed by the infusion of 40-µm microspheres selectively into some or all gastric arteries supplying the gastric fundus. In group 1, 6 swine underwent embolization of all 4 arteries to the gastric fundus. In group 2, 5 swine underwent embolization of 2 gastric fundal arteries. In group 3, 5 swine underwent embolization of 1 gastric fundal artery. Animals in groups 2 and 3 were treated with gastroprotective agents (sucralfate and omeprazole). Weight and fasting plasma ghrelin levels were analyzed at baseline and at week 4. Upon animal euthanasia, gross analysis was performed for identification of ulcers.

RESULTS

Only group 1 animals exhibited changes in serum ghrelin levels that rendered them significantly lower than those in control animals (P = .049). Group 3 animals exhibited marked elevations in serum ghrelin levels compared with control animals (P = .001). Gross pathologic evaluation revealed 0 ulcers in the control animals, 3 ulcers (50%) in group 1, 2 ulcers (40%) in group 2, and 2 ulcers (40%) in group 3.

CONCLUSIONS

Administration of gastroprotective agents and embolization of fewer arteries to the gastric fundus did not prevent gastric ulceration in treated animals. Only animals that underwent embolization of all gastric arteries exhibited significant decreases in serum ghrelin levels.

Gastric Artery Embolization Trial for the Lessening of Appetite Nonsurgically (GET LEAN): Six-Month Preliminary Data

PURPOSE

To report 6-month safety and efficacy results of a pilot study of left gastric artery (LGA) embolization for the treatment of morbid obesity (ie, body mass index [BMI] > 40 kg/m(2)).

MATERIALS AND METHODS

Four white patients (three women; average age, 41 y [range, 30-54 y]; mean weight, 259.3 lbs [range, 199-296 lbs]; mean BMI, 42.4 kg/m(2) [range, 40.2-44.9 kg/m(2)]) underwent an LGA embolization procedure with 300-500-µm Bead Block particles via right common femoral or left radial artery approach. Follow-up included upper endoscopy at 3 days and 30 days if necessary and a gastric emptying study at 3 months. Tracked parameters included adverse events; weight change; ghrelin, leptin, and cholecystokinin levels; and quality of life (QOL; by Short Form 36 version 2 questionnaire).

RESULTS

Three minor complications (superficial gastric ulcerations healed by 30 d) occurred that did not require hospitalization. There were no serious adverse events. Average body weight change at 6 months was -20.3 lbs (n = 4; range, -6 to -38 lbs), or -8.5% (range, -2.2% to -19.1%). Average excess body weight loss at 6 months was -17.2% (range, -4.2% to -38.5%). Patient 4, who had diabetes, showed an improvement in hemoglobin A1c level (7.4% to 6.3%) at 6 months. QOL measures showed a general trend toward improvement, with the average physical component score improving by 9.5 points (range, 3.2-17.2) and mental component score improving by 9.6 points (range, 0.2-19.3) at 6 months.

CONCLUSIONS

Preliminary data support LGA embolization as a potentially safe procedure that warrants further investigation for weight loss in morbidly obese patients.

Bariatric Radioembolization: A Pilot Study on Technical Feasibility and Safety in a Porcine Model

PURPOSE

To evaluate feasibility of left gastric artery (LGA) yttrium-90 ((90)Y) radioembolization as potential treatment for obesity in a porcine model.

MATERIALS AND METHODS

This study included 8 young female pigs (12-13 weeks, 21.8-28.1 kg). Six animals received infusions of (90)Y resin microspheres (46.3-105.1 MBq) into the main LGA and the gastric artery arising from the splenic artery. Animal weight and serum ghrelin were measured before treatment and weekly thereafter. Animals were euthanized 69-74 days after treatment, and histologic analyses of mucosal integrity and ghrelin immunoreactive cell density were performed.

RESULTS

Superficial mucosal ulcerations < 3.0 cm(2) were noted in 5 of 6 treated animals. Ghrelin immunoreactive cell density was significantly lower in treated versus untreated animals in the stomach fundus (13.5 vs 34.8, P < .05) and stomach body (11.2 vs 19.8, P < .05). Treated animals gained less weight than untreated animals over the study duration (40.2 kg ± 5.4 vs 54.7 kg ± 6.5, P = .053). Average fundic parietal area (165 cm(2) vs 282 cm(2), P = .067) and average stomach weight (297.2 g vs 397.0 g, P = .067) were decreased in treated versus untreated animals. Trichrome staining revealed significantly more fibrosis in treatment animals compared with control animals (13.0 vs 8.6, P < .05). No significant differences were identified in plasma ghrelin concentrations (P = .24).

CONCLUSIONS

LGA (90)Y radioembolization is promising as a potential treatment for obesity. A larger preclinical study is needed to evaluate the safety and efficacy of this procedure further.

Bariatric Left Gastric Artery Embolization for the Treatment of Obesity: A Review of Gut Hormone Involvement in Energy Homeostasis

OBJECTIVE

The global population is becoming more overweight and obese, leading to increases in associated morbidity and mortality rates. Advances in catheter-directed embolotherapy offer the potential for the interventional radiologist to make a contribution to weight loss. Left gastric artery embolization reduces the supply of blood to the gastric fundus and decreases serum levels of ghrelin. Early evidence suggests that this alteration in gut hormone balance leads to changes in energy homeostasis and weight reduction. The pathophysiologic findings and current evidence associated with the use of left gastric artery embolization are reviewed.

CONCLUSION

The prevalence of obesity continues to increase at an alarming rate, and, thus far, advances in medical management have been relatively ineffective in slowing this trend. Lifestyle modifications such as diet and exercise are effective initially, but most patients regain the weight in the long term. Bariatric surgery is the most effective strategy for achieving long-term weight loss; however, as with all surgical procedures, it has potential complications.

Minimally invasive percutaneous endovascular therapies in the management of complications of non-alcoholic fatty liver disease (NAFLD): A case report

Nonalcoholic fatty liver disease (NAFLD) represents a spectrum of disorders from simple steatosis to inflammation leading to fibrosis, cirrhosis, and even hepatocellular carcinoma. With the progressive epidemics of obesity and diabetes, major risk factors in the development and pathogenesis of NAFLD, the prevalence of NAFLD and its associated complications including liver failure and hepatocellular carcinoma is expected to increase by 2030 with an enormous health and economic impact. We present a patient who developed Hepatocellular carcinoma (HCC) from nonalcoholic steatohepatitis (NASH) cirrhosis. Due to morbid obesity, she was not an optimal transplant candidate and was not initially listed. After attempts for lifestyle modifications failed to lead to weight reduction, a transarterial embolization of the left gastric artery was performed. This is the sixth such procedure in humans in literature. Subsequently she had a meaningful drop in BMI from 42 to 36 over the following 6 months ultimately leading to her being listed for transplant. During this time, the left hepatic HCC was treated with chemoembolization without evidence of recurrence. In this article, we wish to highlight the use of minimally invasive percutaneous endovascular therapies such as transarterial chemoembolization (TACE) in the comprehensive management of the NAFLD spectrum and percutaneous transarterial embolization of the left gastric artery (LGA), a novel method, for the management of obesity.

The Global Nonalcoholic Fatty Liver Disease Epidemic: What a Radiologist Needs to Know

Nonalcoholic fatty liver disease (NAFLD) represents a spectrum of disorders from a benign steatosis to hepatocellular carcinoma (HCC). Metabolic syndrome, mainly obesity, plays an important role, both as an independent risk factor and in the pathogenesis of NAFLD. With the progressive epidemics of obesity and diabetes mellitus, the prevalence of NAFLD and its associated complications is expected to increase dramatically. Therapeutic strategies for treating NAFLD and metabolic syndrome, particularly obesity, are continuously being refined. Their goal is the prevention of NAFLD by the management of risk factors, prevention of progression of the disease, as well as management of complications, ultimately preventing morbidity and mortality. Optimal management of NAFLD and metabolic syndrome requires a multidisciplinary collaboration between the government as well as the health system including the nutritionist, primary care physician, radiologist, hepatologist, oncologist, and transplant surgeon. An awareness of the clinical presentation, risk factors, pathogenesis, diagnosis, and management is of paramount importance to a radiologist, both from the clinical perspective as well as from the imaging standpoint. With expertise in imaging modalities as well as minimally invasive percutaneous endovascular therapies, radiologists play an essential role in the comprehensive management, which is highlighted in this article, with cases from our practice. We also briefly discuss transarterial embolization of the left gastric artery (LGA), a novel method that promises to have an enormous potential in the minimally invasive management of obesity, with details of a case from our practice.

Bariatric embolization of the gastric arteries for the treatment of obesity

Obesity is a public health epidemic in the United States that results in significant morbidity, mortality, and cost to the health care system. Despite advancements in therapeutic options for patients receiving bariatric procedures, the number of overweight and obese individuals continues to increase. Therefore, complementary or alternative treatments to lifestyle changes and surgery are urgently needed. Embolization of the left gastric artery, or bariatric arterial embolization (BAE), has been shown to modulate body weight in animal models and early clinical studies. If successful, BAE represents a potential minimally invasive approach offered by interventional radiologists to treat obesity. The purpose of the present review is to introduce the interventional radiologist to BAE by presenting its physiologic and anatomic bases, reviewing the preclinical and clinical data, and discussing current and future investigations.

Embolization of arterial gastric supply in obesity (EMBARGO): an endovascular approach in the management of morbid obesity. proof of the concept in the porcine model

BACKGROUND

Embolization of the left gastric artery (LGA) reduces circulating levels of ghrelin, but might prevent from further obesity surgery, particularly sleeve gastrectomy (SG), since the gastroesophageal junction (GEJ), depending on LGA, would be devascularized. Our aim was to evaluate, in an experimental animal study, an endovascular approach targeting arteries of the gastroepiploic arcade aiming to modulate ghrelin levels and to generate an increased vascular supply of the GEJ to reduce the risks of staple-line leaks after SG.

METHODS

Seven pigs underwent embolization of both left and right gastroepiploic arteries (LGEA and RGEA) using 500-700-μ microspheres (embolization of arterial gastric supply in obesity (EMBARGO)-alpha). A SG was performed in six pigs 3 weeks after EMBARGO-alpha and on eight controls. Capillary lactates were measured at the cardia and pylorus. Five pigs underwent coiling of RGEA and embolization of LGEA using both coils and 100-300-μ microspheres (EMBARGO-beta). Ghrelin levels were assessed before and once per week after both EMBARGOs. Control celiac trunk angiography was performed at 3 weeks (alpha) and 4 weeks (beta).

RESULTS

No significant ghrelin reduction was obtained with EMBARGO-alpha at 3 weeks when compared to baseline. Significant ghrelin reduction was found 3 weeks (p = 0.0363) and 4 weeks (p = 0.025) after EMBARGO-beta. Post-EMBARGO-alpha animals presented a significantly lower increase in cardia lactates when compared to controls after SG. Control angiography showed a significantly increased fundic vascular network in 5/6 animals after EMBARGO-alpha and in 5/5 after EMBARGO-beta.

CONCLUSIONS

EMBARGO is effective to decrease ghrelin production and can enhance the vascular supply of the GEJ, preparing the vascular background for a SG.

Gastric supply manipulation to modulate ghrelin production and enhance vascularization to the cardia: proof of the concept in a porcine model

INTRODUCTION

Selective embolization of the left-gastric artery (LGA) reduces levels of ghrelin and achieves significant short-term weight loss. However, embolization of the LGA would prevent the performance of bariatric procedures because the high-risk leakage area (gastroesophageal junction [GEJ]) would be devascularized.

AIM

To assess an alternative vascular approach to the modulation of ghrelin levels and generate a blood flow manipulation, consequently increasing the vascular supply to the GEJ.

MATERIALS AND METHODS

A total of 6 pigs underwent a laparoscopic clipping of the left gastroepiploic artery. Preoperative and postoperative CT angiographies were performed. Ghrelin levels were assessed perioperatively and then once per week for 3 weeks. Reactive oxygen species (ROS; expressed as ROS/mg of dry weight [DW]), mitochondria respiratory rate, and capillary lactates were assessed before and 1 hour after clipping (T0 and T1) and after 3 weeks of survival (T2), on seromuscular biopsies. A celiac trunk angiography was performed at 3 weeks.

RESULTS

Mean (±standard deviation) ghrelin levels were significantly reduced 1 hour after clipping (1902 ± 307.8 pg/mL vs. 1084 ± 680.0; P = .04) and at 3 weeks (954.5 ± 473.2 pg/mL; P = .01). Mean ROS levels were statistically significantly decreased at the cardia at T2 when compared with T0 (0.018 ± 0.006 mg/DW vs. 0.02957 ± 0.0096 mg/DW; P = .01) and T1 (0.0376 ± 0.008 mg/DW; P = .007). Capillary lactates were significantly decreased after 3 weeks, and the mitochondria respiratory rate remained constant over time at the cardia and pylorus, showing significant regional differences.

CONCLUSIONS

Manipulation of the gastric flow targeting the gastroepiploic arcade induces ghrelin reduction. An endovascular approach is currently under evaluation.

Histopathologic and immunohistochemical sequelae of bariatric embolization in a porcine model

PURPOSE

To evaluate the histopathologic sequelae of bariatric embolization on the gastric mucosa and to correlate with immunohistochemical evaluation of the gastric fundus, antrum, and duodenum.

MATERIALS AND METHODS

This study was performed on 12 swine stomach and duodenum specimens after necropsy. Of the 12 swine, 6 had previously undergone bariatric embolization of the gastric fundus, and the 6 control swine had undergone a sham procedure with saline. Gross pathologic, histopathologic, and immunohistochemical examinations of the stomach and duodenum were performed. Specifically, mucosal integrity, fibrosis, ghrelin-expressing cells, and gastrin-expressing cells were assessed.

RESULTS

Gross and histopathologic evaluation of treatment animals showed healing or healed mucosal ulcers in 50% of animals, with gastritis in 100% of treatment animals and in five of six control animals. The ghrelin-immunoreactive mean cell density was significantly lower in the gastric fundus in the treated animals compared with control animals (15.3 vs 22.0, P < .01) but similar in the gastric antrum (9.3 vs 14.3, P = .08) and duodenum (8.5 vs 8.6, P = .89). The gastrin-expressing cell density was significantly lower in the antrum of treated animals compared with control animals (82.2 vs 126.4, P = .03). A trend toward increased fibrosis was suggested in the gastric fundus of treated animals compared with controls (P = .07).

CONCLUSIONS

Bariatric embolization resulted in a significant reduction in ghrelin-expressing cells in the gastric fundus without evidence of upregulation of ghrelin-expressing cells in the duodenum. Healing ulcerations in half of treated animals underscores the need for additional refinement of this procedure.

A preliminary observation of weight loss following left gastric artery embolization in humans

BACKGROUND/OBJECTIVES

Embolization of the left gastric artery (LGA), which preferentially supplies the gastric fundus, has been shown to produce weight loss in animal models. However, weight loss after LGA embolization in humans has not been previously established. The aim of this study was to evaluate postprocedural weight loss in patients following LGA embolization.

SUBJECTS/METHODS

A retrospective analysis of the medical records of patients who underwent LGA embolization for upper gastrointestinal (GI) bleeding was performed. Postprocedural weight loss in this group was compared to a control group of patients who had undergone embolization of other arteries for upper GI bleeding.

RESULTS

The experimental group (N = 19) lost an average of 7.3% of their initial body weight within three months of LGA embolization, which was significantly greater than the 2% weight loss observed in the control group (N = 28) (P = 0.006). No significant differences were seen between the groups in preprocedural body mass index (BMI), age, postprocedural care in the intensive care unit, history of malignancy, serum creatinine, or left ventricular ejection fraction.

CONCLUSIONS

The current data suggest that body weight in humans may be modulated via LGA embolization. Continued research is warranted with prospective studies to further investigate this phenomenon.

Bariatric embolization for suppression of the hunger hormone ghrelin in a porcine model

PURPOSE

To prospectively test in a porcine model the hypothesis that bariatric embolization with commercially available calibrated microspheres can result in substantial suppression of systemic ghrelin levels and affect weight gain over an 8-week period.

MATERIALS AND METHODS

The institutional animal care and use committee approved this study. Twelve healthy growing swine (mean weight, 38.4 kg; weight range, 30.3-47.0 kg) were evaluated. Bariatric embolization was performed by infusion of 40-μm calibrated microspheres selectively into the gastric arteries that supply the fundus. Six swine underwent bariatric embolization, while six control animals underwent a sham procedure with saline. Weight and fasting plasma ghrelin and glucose levels were obtained in animals at baseline and at weeks 1-8. Statistical testing for differences in serum ghrelin levels and weight at each time point was performed with the Wilcoxon signed rank test for intragroup differences and the Wilcoxon rank sum test for intergroup differences.

RESULTS

The pattern of change in ghrelin levels over time was significantly different between control and experimental animals. Weekly ghrelin levels were measured in control and experimental animals as a change from baseline ghrelin values. Average postprocedure ghrelin values increased by 328.9 pg/dL ± 129.0 (standard deviation) in control animals and decreased by 537.9 pg/dL ± 209.6 in experimental animals (P = .004). The pattern of change in weight over time was significantly different between control and experimental animals. The average postprocedure weight gain in experimental animals was significantly lower than that in control animals (3.6 kg ± 3.8 vs 9.4 kg ± 2.8, respectively; P = .025).

CONCLUSION

Bariatric embolization can significantly suppress ghrelin and significantly affect weight gain. Further study is warranted before this technique can be used routinely in humans.