Stretta procedure
Stretta is a minimally invasive endoscopic procedure for the treatment of gastroesophageal reflux disease (GERD). A catheter is used to deliver radiofrequency energy to the lower esophageal sphincter, muscle and gastric cardia. The trans-oral Stretta catheter system uses a proprietary application of RF energy that is low-power (5 Watts) and generates low temperatures (65 °C to 85 °C) during a series of 14 one-minute cycles which remodel the lower esophageal sphincter (LES) muscle and gastric cardia. The FDA originally cleared Stretta for use in 2000 and issued an updated clearance on the RF1 generator in 2011.
One review found that the treatment improves symptoms[1] while another review found no effect on underlying disease or need for other treatments.[2]
Contents
Medical uses
A 2015 systematic review and meta-analysis in response to the systematic review (no meta-analysis) conducted by SAGES did not support the claims that Stretta was an effective treatment for GERD.[2] A 2012 systematic review found that it improves GERD symptoms.[1]
Procedure
The Stretta device design and function specifically allows for treatment of the muscularis propria. Patients typically receive conscious sedation with a combination of midazolam and fentanyl. First, a diagnostic upper endoscopy is performed to locate the gastroesophageal junction. Upon endoscope removal, a wire-guided flexible RF delivery catheter (a balloon-basket assembly with four treatment elements positioned radially around the balloon) is passed transorally then positioned within the gastroesophageal junction. After appropriate balloon inflation (<2.5 psi), the treatment elements are deployed 3–4 mm into the LES muscle, where energy is delivered in a series of thermal treatments at four levels in two positions (distal esophagus) and at two levels in three positions (gastric cardia). The monitoring of temperature and impedance at each treatment element ensured safe and precise RF delivery. As RF energy is applied during the procedure, chilled water is irrigated from the catheter to the esophageal mucosa to prevent unintended treatment of that tissue. After completion of the procedure and catheter removal, the endoscopy is repeated to verify that there have been no complications. All pre-Stretta medication is maintained for 6–8 weeks after the procedure to maintain baseline and allow time for complete procedural effect, and prevent potential complications.
Mechanism of action
The Stretta device design and function specifically allows for treatment of the muscularis propria only, and neither the mucosa or submucosa. After proper positioning, the thermocouple-controlled device monitors impedance, temperature, and regulates energy output. Typical impedance values are 70-200 ohms on a scale of 1-1000, indicative of placement in dense saturated muscle tissue. Higher impedance values cause generator shutoff, preventing unintended treatment of mucosa or submucosa. The device maintains muscularis temperatures at 65-85 °C levels for short duration, well below treatment time and temperature to induce fibrosis or necrosis. No publication or other evidence exists demonstrating fibrosis or restriction. Recent works demonstrate that low power/low temperature radiofrequency stimulation results in muscle fiber bundle proliferation and increased muscle cell volume within each bundle, causing sphincter lengthening, thickening, and increased physiological barrier function.[3] The effect of these physiological changes is further borne out by studies that have confirmed increased LES tone,[1][4][5] reduced esophageal acid exposure with reported normalization of pH,[1][4][6][7] increased gastric yield pressure,[8] and improvements in gastric emptying[9] and gastric motility.[10] Importantly, what has not been demonstrated is denervation or desensitization of the esophagus, with a number of studies refuting this conjecture[5][6][7][9] There are no histopathological studies demonstrating neurolysis or desensitization within the esophagus after Stretta but instead there is supporting evidence of effects based on physiological data.
Recognition
In 2013, the Society of American Gastroenterological Endoscopic Surgeons considered Stretta appropriate for some people who refuse laparoscopic fundoplication.[11]
An American Society of Gastrointestinal Endoscopy (ASGE) statement in June 2015 state that endoscopic antireflux therapy is a potential treatment based on the 2012 review.[12]
References
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