Stomach pacemaker for weight loss


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  • Phasic contractions are driven by slow waves generated by pacemaker ICC – depolarizations enable Ca2+ Entry – action potential – electromechanical Coupling Motility of GI tract is results from coordinated contractions of smooth muscle, which in turn derive from two basic patterns of electrical activity across the membranes of smooth muscle cells — slow waves and action potentials.[2] Slow waves are initiated by pacemakers — the interstitial cells of Cajal (ICC). Slow wave frequency varies in the different organs of the GI tract and is characteristic for that organ. They set the maximum frequency at which the muscle can contract: stomach — about 3 waves in a minute – during fasting, these do not result in contractions. For 2-3 hours after meals, spikes are superimposed on slow waves – result in contractions that propogate distally. Bradygastria – assocaited with GP Tachygastria Disorganised – dysrthythmia duodenum — about 12 waves in a minute, ileum — about 8 waves in a minute, rectum — about 17 waves in a minute.[3] jejunum — about 11 waves in a minute.[4]
  • Stomach pacemaker for weight loss

    1. 1. Abeezar I. Sarela Consultant in Upper GI & Bariatric Surgery St James’s University Hospital & The Nuffield Hospital Leeds, UK Gastric Neuromodulation (Electric Stimulation) for Obesity
    2. 2. Agenda <ul><li>Bariatric surgery: why gastric electrical stimulation (GES)? </li></ul><ul><li>Understand gastric electrophysiology </li></ul><ul><li>Trace evolution of GES for obesity </li></ul><ul><li>Currrent status of GES for obesity </li></ul>
    3. 3. Surgery for Obesity <ul><li>Global epidemic of obesity </li></ul><ul><li>Bariatric surgery is the only effective and sustained treatment for morbid obesity </li></ul><ul><li>Bariatric surgery resolves diabetes and other co-morbidity and saves lives </li></ul><ul><li>Laparoscopic surgery has significant advantages over open procedures </li></ul><ul><li>Surgical morbidity and mortality are very low in experienced units </li></ul>
    4. 4. But…….. <ul><li>Aetiology of obesity is multi-factorial </li></ul><ul><li>Bariatric surgery is not a cure for obesity </li></ul><ul><li>Substantial incidence of weight regain </li></ul><ul><li>Definite short, medium and long-term risks with all bariatric operations </li></ul>
    5. 5. The Search is On…. <ul><li>Behaviour modification </li></ul><ul><li>Monitor activity and eating pattern </li></ul><ul><li>Adjustable parameters </li></ul><ul><li>Technology-friendly </li></ul><ul><li>Low surgical risk </li></ul><ul><li>Wide applicability </li></ul>
    6. 6. Gastric Neuromuscular Function <ul><li>Gastric slow waves (Phasic): 3/min </li></ul><ul><li>Tonic spikes superimposed on slow waves result in smooth muscle contraction </li></ul>Soffer et al. Aliment Pharmacol Ther 2009;30:681-694
    7. 7. Gastric Electrical Stimulation (GES) <ul><li>Gastric Pacing: </li></ul><ul><li>Entrain slow waves </li></ul><ul><li>Low-frequency + Long duration </li></ul><ul><li>Implantable Pulse Generator (IPG) not available </li></ul><ul><li>Implantable GES </li></ul><ul><li>High frequency + Short duration </li></ul><ul><li>Slow waves not altered </li></ul><ul><li>Neural stimulation </li></ul>Clinically Used GES is NOT pacing
    8. 8. Implantable Gastric Electrical Stimulators
    9. 9. Implantation of Gastric Electrodes
    10. 10. Features <ul><li>Behaviour modification </li></ul><ul><li>Stimulation parameters </li></ul><ul><ul><li>Fixed vs. Adjustable </li></ul></ul><ul><li>Duration of stimulation </li></ul><ul><ul><li>Constant vs. Episodic </li></ul></ul><ul><li>Intelligent sensing </li></ul>
    11. 11. How does it work? <ul><li>Short pulse-width and high frequency electrical stimulation </li></ul><ul><ul><li>Increases afferent vagal activity </li></ul></ul><ul><ul><li>Blocks efferent vagal activity </li></ul></ul><ul><ul><li>Gastric distention </li></ul></ul><ul><ul><li>Inhibits post-prandial antral contractions </li></ul></ul><ul><ul><li>Slows gastric emptying </li></ul></ul><ul><ul><li>Inhibition of post-prandial gastric slow waves </li></ul></ul>
    12. 12. Transcend IGS ™ System Transneuronix - Medtronics <ul><li>800 patients world-wide </li></ul><ul><li>10 years follow-up </li></ul><ul><li>35% excess weight loss </li></ul>
    13. 13. Transcend IGS ™ - SHAPE Trial <ul><li>Randomised, placebo-controlled, double-blind trial </li></ul><ul><li>190 patients at 8 centres </li></ul><ul><li>Primary end point: >10% EWL </li></ul><ul><ul><li>%EWL: Active vs. Sham </li></ul></ul><ul><ul><ul><li>11.8 ±17.6% vs. 11.7±16.9% </li></ul></ul></ul><ul><ul><li>EWL>20%: Active vs. Sham </li></ul></ul><ul><ul><ul><li>27% vs. 16% </li></ul></ul></ul>Shikora et al. SOARD 2009 WITHDRAWN
    14. 14. MetaCure (2003; CE Mark 2006) TANTALUS ™ - Diabetes Control Technology <ul><li>13 patients </li></ul><ul><li>3 months therapy </li></ul><ul><li>Weight 104 kg 100 kg </li></ul><ul><li>HbA1c 8.0 6.9 </li></ul><ul><li>Glucose 175 mg/dl 127 mg/dl </li></ul>Bohdjalian et al. Surg Endosc. 2009
    15. 15. EnteroMedics (2002) VBLOC ™ Therapy
    16. 16. VBLOC ™ - EMPOWER Trial <ul><li>Multi-centre </li></ul><ul><li>1 year double-blind, 4 years open-label </li></ul><ul><li>2:1 randomization </li></ul><ul><li>300 subjects, BMI 35-45 kg/m 2 </li></ul>
    17. 17. EnteroMedics - VBLOC ™ <ul><li>CE mark - 2009 </li></ul><ul><li>VBLOC Therapy - Maestro system </li></ul><ul><ul><li>pending FDA approval </li></ul></ul><ul><ul><li>USA commercialization in 2010 </li></ul></ul>?
    18. 18. <ul><li>Gastric Stimulation </li></ul><ul><ul><li>Creates early sensation of satiety </li></ul></ul><ul><ul><li>Reduces desire to eat between meals </li></ul></ul><ul><ul><li>Reduced meal volume </li></ul></ul><ul><li>Patient Support System </li></ul><ul><ul><li>Tracks & reports eating events </li></ul></ul><ul><ul><li>Tracks & reports exercise trends </li></ul></ul><ul><ul><li>Useful diagnostic for sleep disorders </li></ul></ul><ul><ul><li>Supports behavior modification </li></ul></ul><ul><li>Low Impact </li></ul><ul><ul><li>Excellent safety profile </li></ul></ul><ul><ul><li>Minimal lifestyle changes </li></ul></ul><ul><ul><ul><li>No special diets </li></ul></ul></ul><ul><ul><ul><li>No vitamin supplements </li></ul></ul></ul>IntraPace: Abiliti™ Consumption - Expenditure Wt Change =
    19. 19. IntraPace: abiliti ™ GSA102 Analyzer P102 Programmer W102 Programmer Wand LGS102 Stimulator LGL102 Lead
    20. 20. Endoscopy 6 Months Post-Implant
    21. 21. Study Population Unpublished data Number of Subjects 30 Gender 25 Females / 5 Males Age (years) Mean, range 40 (20 to 60) Weight (lb) Mean, range 284.6 ( 213.4 to 370) Excess weight (lb) 124.6 (72.9 to 177.5) BMI Mean, range 43.8 (32.5 to 55)
    22. 22. Abiliti ™: Weight Loss Unpublished data
    23. 23. Conclusions <ul><li>Licensed (very shortly) in Europe and USA </li></ul><ul><li>Attractive features </li></ul><ul><ul><li>Diet & Behaviour modification </li></ul></ul><ul><ul><li>Intelligence </li></ul></ul><ul><ul><li>Adjustment </li></ul></ul><ul><li>Convincing potential for weight control </li></ul><ul><li>Diabetes resolution </li></ul>
    24. 24. Emerging Paradigms in Obesity Therapy <ul><li>Super-Obesity: Conventional Bariatric Surgery e.g. laparoscopic gastric bypass </li></ul><ul><li>Less Severe Obesity </li></ul><ul><ul><li>Classes 1 and 2 </li></ul></ul><ul><ul><li>Class 3 with BMI<45 kg/m 2 </li></ul></ul><ul><ul><ul><li>Gastric Electrical Stimulation </li></ul></ul></ul><ul><ul><ul><li>Endoscopic bariatric procedures </li></ul></ul></ul>