EMPOWER Clinical Trial: Vagal Blocking for Obesity Control (EMPOWER)

This study is ongoing, but not recruiting participants.
Information provided by:
ClinicalTrials.gov Identifier:
First received: August 23, 2007
Last updated: September 5, 2008
Last verified: September 2008
This is a randomized multi-center study being done to measure the ability of a new medical device, Maestro System, to safely reduce body weight over five years in people who are considered obese.

Condition Intervention
Device: Active, implantable, intra-abdominal vagal blocking medical device

Study Type: Interventional
Study Design: Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Double Blind (Subject, Caregiver, Investigator, Outcomes Assessor)
Primary Purpose: Treatment
Official Title: EMPOWER Clinical Trial: Vagal Blocking for Obesity Control

Further study details as provided by EnteroMedics:

Primary Outcome Measures:
  • To demonstrate a significantly greater percentage of excess weight loss with the Maestro System which provides VBLOC therapy. [ Time Frame: 1 Year ]
  • To estimate the rate of serious, system- and procedure-related adverse events associated with the Maestro System. [ Time Frame: 1 Year ]

Secondary Outcome Measures:
  • To demonstrate a significant difference between treatment groups in the proportion of subjects realizing at least a 25% excess weight loss from implant. [ Time Frame: 1 Year ]

Estimated Enrollment: 300
Study Start Date: August 2007
Estimated Study Completion Date: June 2013
Arms Assigned Interventions
Experimental: A
Subjects will be implanted with the Maestro System and are randomized to having VBLOC therapy ON.
Device: Active, implantable, intra-abdominal vagal blocking medical device
Intermittent, programmable, intra-abdominal vagal blocking
Other Name: Maestro System
Placebo Comparator: B
Subjects will be implanted with the Maestro System and are randomized to having VBLOC therapy OFF.
Device: Active, implantable, intra-abdominal vagal blocking medical device
Intermittent, programmable, intra-abdominal vagal blocking
Other Name: Maestro System

Detailed Description:

The Maestro System is a neuromodulation system that consists of implantable and external components.

Implantable components: two leads (one electrode each for the anterior and posterior intra-abdominal vagal nerve trunks) that are connected to an implantable neuroregulator.

External components: one programmable, battery-powered, ambulatory external controller connected via a small, flexible cable to a cutaneous transmit coil that is positioned over the neuroregulator. A clinician programmer that transmits information to the controller and uploads data from the controller.

All non-diabetic subjects will be randomized in a 2:1 allocation to therapy ON or therapy OFF groups. All type 2 diabetes mellitus subjects will be randomized in a 1:1 allocation to therapy ON or therapy OFF groups.

All subjects will receive blinded therapy through the 12-month follow-up visit. All subjects will participate in a medical weight management program.


Ages Eligible for Study:   18 Years to 65 Years   (Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   No

Inclusion Criteria:

  • Informed consent.
  • Body mass index (BMI) ≥ 40 kg/m2 to 45 kg/m2 or BMI ≥ 35 kg/m2 to 39.9 kg/m2 with one or more severe obesity related co-morbid condition.
  • Females or males
  • 18-65 years of age inclusive.
  • Type 2 diabetes mellitus subjects that are well-controlled (at selected centers, limited to approximately 26 subjects).
  • Failure to respond to supervised diet/exercise program(s) in which the subject was engaged for at least 6 months.
  • Ability to complete all study visits and procedures.

Exclusion Criteria:

  • Concurrent chronic pancreatic disease.
  • History of Crohn's disease and/or ulcerative colitis.
  • History of bariatric surgery, fundoplication, gastric resection or major upper-abdominal surgery.
  • History of pulmonary embolism or blood coagulation disorders.
  • Clinically significant hiatal hernias known from subject's medical record as or determined by upper endoscopy prior to implant.
  • Current portal hypertension and/or esophageal varices.
  • Intra-operative exclusion: hiatal hernia requiring surgical repair or extensive dissection at esophagogastric junction at time of surgery.
  • Treatment with weight-loss prescription drug therapy within the prior three months and the use of prescription drug therapy or the use over-the-counter weight loss preparations for the duration of the trial.
  • Smoking cessation within the prior six months.
  • Known genetic cause of obesity.
  • Overall sustained reduction of more than 10% of body weight in the previous 12 months.
  • Pre-operative diet with intent to lose weight prior to surgery.
  Contacts and Locations
Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the Contacts provided below. For general information, see Learn About Clinical Studies.

Please refer to this study by its ClinicalTrials.gov identifier: NCT00521079

United States, Arizona
Scottsdale Bariatric Center
Scottsdale, Arizona, United States, 85258
United States, California
Scripps Clinic
La Jolla, California, United States, 92037
University of California, Irvine Medical Center
Orange, California, United States, 92868
Stanford University Medical Center
Stanford, California, United States, 94305
United States, Florida
Cleveland Clinic - Florida
Weston, Florida, United States, 33331
United States, Maryland
Johns Hopkins
Baltimore, Maryland, United States, 21224
United States, Massachusetts
Tufts New England Medical Center
Boston, Massachusetts, United States, 02111
United States, Minnesota
University of Minnesota
Minneapolis, Minnesota, United States, 55455
Mayo Clinic
Rochester, Minnesota, United States, 55905
United States, Missouri
Washington University School of Medicine
St. Louis, Missouri, United States, 63110
United States, Ohio
Cleveland Clinic - Ohio
Cleveland, Ohio, United States, 44195
United States, Oregon
Oregon Health & Science University
Portland, Oregon, United States, 97239-3098
United States, Virginia
Virginia Commonwealth University
Richmond, Virginia, United States, 23298
Australia, New South Wales
Institute of Weight Control
Sydney, New South Wales, Australia, 2153
Australia, South Australia
Adelaide Bariatric Center - Flinders Private Hospital
Bedford Park, South Australia, Australia, 5042
Sponsors and Collaborators
Principal Investigator: Charles J Billington, MD VA Medical Center, Minneapolis, MN / University of Minnesota
Principal Investigator: Michael Sarr, MD Mayo Clinic
  More Information

Additional Information:
Responsible Party: Dennis Kim, VP Medical Affairs & Chief Medical Officer, EnteroMedics Inc.
ClinicalTrials.gov Identifier: NCT00521079     History of Changes
Other Study ID Numbers: D00343-000 
Study First Received: August 23, 2007
Last Updated: September 5, 2008

Keywords provided by EnteroMedics:
Bariatric surgery
Excess weight loss
Vagus nerve
Vagal blocking
VBLOC(TM) therapy

Additional relevant MeSH terms:
Nutrition Disorders
Body Weight
Signs and Symptoms

ClinicalTrials.gov processed this record on January 19, 2017