The Stretta Catheter
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. Clinical studies demonstrate that Stretta RF treatment results in significant reductions in tissue compliance and transient LES relaxations, as well as increased LES wall thickness due to muscle growth. These mechanisms restore the natural barrier function of the LES and reduce spontaneous regurgitation caused by transient relaxations of the sphincter, two of the leading causes of GERD.
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. The effect of these physiological changes is further borne out by studies that have confirmed increased LES tone, reduced esophageal acid exposure with reported normalization of pH, increased gastric yield pressure, and improvements in gastric emptying and gastric motility. Importantly, what has not been demonstrated is denervation or desensitization of the esophagus, with a number of studies refuting this conjecture 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.
There have been four randomized control trials (RCT) to date, three of which included a sham-control arm. These trials demonstrated significant improvements in different parameters including GERD-health related quality of life (GERD-HRQL), LES pressure, esophageal acid exposure, and proton pump inhibitor (PPI) use. Within the Arts et al. sham RCT active treatment group, GERD symptoms improved significantly (p<0.005) in contrast to non-significant improvement after sham (p>0.05) which subsequently significantly improved after crossover (p<0.05). The primary outcome measure, barostat distensibility of the esophagogastric junction, before and after sildenafil administration, demonstrated that Stretta was associated with significant decrease in tissue compliance (17.8±3.6 vs. 7.4±3.4 ml/mmHg, p<0.05), which normalized after administration of sildenafil, contrary to the sham group (14.0±5.3 vs. 13.3±4.30 ml/mmHg, p>0.05). This demonstrates reduction in tissue compliance is an important factor in Stretta’s mechanistic effect. Additional evidence in the Aziz et al. sham RCT of single and double-dose Stretta found that at 12-months post-Stretta GERD-HRQL, LES pressure, esophageal acid exposure, and PPI consumption significantly improved from baseline in both treatment groups. Esophageal acid exposure within sham did not significantly change from baseline to 12-month follow-up (9.9±2.6 vs. 8.2±3.1, p>0.05) whereas in single (9.4±3.4 vs. 6.7±2.8, p<0.01) and double (8.8±2.8 vs. 5.2±2.4, p<0.01) Stretta there was a significant decline. Similarly in a sham RCT by Corley et al. active treatment significantly improved heartburn scores, GERD-HRQL scores, and general quality of life (SF-36) at 6-months compared with sham. Esophageal acid exposure decreased significantly from baseline to 12-months (p=0.01) for both initial active and crossed-over patients. In the Coron et al. RCT intent-to-treat analysis, 90% of patients stopped or decreased PPI use at 6 months demonstrating significance compared with the PPI control group (P=0.01).
A meta-analysis of 20 studies including 1441 patients showed significant improvements in all objective and subjective outcomes measured including most notably: 1) 433 patients in 9 studies with GERD-HRQL scores improved from 26.11±27.2 to 9.25±23.7 post-treatment (P=0.0001), 2) 11 studies with 364 patients with AET decreasing from 10.29±17.8% to 6.51±12.5% (P=0.0003), and 3) 263 subjects in 7 studies with LES pressure improving from 16.54±34.7 mmHg pre-Stretta to 20.24±29.1 mmHg post-Stretta (P=0.03). A recently published analysis of 217 refractory GERD patients taking a minimum of twice-daily PPI demonstrated that 10 years post-Stretta, 72% of patients achieved normalization of GERD symptoms, 54% reached a ≥60% increase in satisfaction, and 64% decreased medication use by at least half. 41% of patients were taking no regular medical therapy, and 34% were on single dose PPI. Notably, there was an 85% regression in Barrett’s metaplasia.
With multiple randomized sham-controlled trials, a meta-analysis, as well as more than 40 short and long-term studies, evidence suggests Stretta is a safe, effective and mature technology which physiologically aids in the correction of reflux and the limiting of the disease process.
- Herman R, Wojtysiak D, Rys J, Nowakowski M, Schwartz T, Murawski M, et al. Interstitial Cells of Cajal (ICCs) and Smooth Muscle Actin (SMA) Activity After Non-Ablative Radiofrequency Energy Application to the Internal Anal Sphincter (IAS): An Animal Study. Gastroenterology. 2013;144(5):S-372.
- Arts J, Bisschops R, Blondeau K, Farre R, Vos R, Holvoet L, et al. A double-blind sham-controlled study of the effect of radiofrequency energy on symptoms and distensibility of the gastro-esophageal junction in GERD. The American journal of gastroenterology. 2012;107(2):222-30.
- Perry KA, Banerjee A, Melvin WS. Radiofrequency energy delivery to the lower esophageal sphincter reduces esophageal acid exposure and improves GERD symptoms: a systematic review and meta-analysis. Surgical laparoscopy, endoscopy & percutaneous techniques. 2012;22(4):283-8.
- Tam WC, Schoeman MN, Zhang Q, Dent J, Rigda R, Utley D, et al. Delivery of radiofrequency energy to the lower oesophageal sphincter and gastric cardia inhibits transient lower oesophageal sphincter relaxations and gastro-oesophageal reflux in patients with reflux disease. Gut. 2003;52(4):479-85.
- Arts J, Sifrim D, Rutgeerts P, Lerut A, Janssens J, Tack J. Influence of radiofrequency energy delivery at the gastroesophageal junction (the Stretta procedure) on symptoms, acid exposure, and esophageal sensitivity to acid perfusion in gastroesophagal reflux disease. Digestive diseases and sciences. 2007;52(9):2170-7.
- Triadafilopoulos G. Changes in GERD symptom scores correlate with improvement in esophageal acid exposure after the Stretta procedure. Surgical endoscopy. 2004;18(7):1038-44.
- Richards WO, Houston HL, Torquati A, Khaitan L, Holzman MD, Sharp KW. Paradigm shift in the management of gastroesophageal reflux disease. Annals of surgery. 2003;237(5):638-47; discussion 48-9.
- Utley DS, Kim M, Vierra MA, Triadafilopoulos G. Augmentation of lower esophageal sphincter pressure and gastric yield pressure after radiofrequency energy delivery to the gastroesophageal junction: a porcine model. Gastrointest Endosc 2000;52(1):81–86.
- Noar MD, Noar E. Gastroparesis associated with gastroesophageal reflux disease and corresponding reflux symptoms may be corrected by radiofrequency ablation of the cardia and esophagogastric junction. Surgical endoscopy. 2008;22(11):2440-4.
- Noar MD, Xu L, Koch KL. Effect of radiofrequency ablation on gastric dysrhythmias in patients with gastroesophageal reflux disease (GERD) and functional dyspepsia. Gastroenterology.2003;124(4):A98.
- Aziz AM, El-Khayat HR, Sadek A, Mattar SG, McNulty G, Kongkam P, et al. A prospective randomized trial of sham, single-dose Stretta, and double-dose Stretta for the treatment of gastroesophageal reflux disease. Surgical endoscopy. 2010;24(4):818-25.
- Corley DA, Katz P, Wo JM, Stefan A, Patti M, Rothstein R, et al. Improvement of gastroesophageal reflux symptoms after radiofrequency energy: a randomized, sham-controlled trial. Gastroenterology. 2003;125(3):668-76.
- Coron E, Sebille V, Cadiot G, Zerbib F, Ducrotte P, Ducrot F, et al. Clinical trial: Radiofrequency energy delivery in proton pump inhibitor-dependent gastro-oesophageal reflux disease patients. Alimentary pharmacology & therapeutics. 2008;28(9):1147-58.
- Noar M, Squires P, Noar E, Lee M. Long-term maintenance effect of radiofrequency energy delivery for refractory GERD: a decade later. Surgical endoscopy. 2014;28(8):2323-33.