Post written by Yusuke Fujiyoshi, MD, and Christopher Teshima, MD, MSc, PhD, from the Advanced Therapeutic Endoscopy Centre, St Michael’s Hospital, University of Toronto, Toronto, Ontario, Canada.

We experienced a peroral endoscopic myotomy (POEM) case in which the EndoFLIP (Medtronic, Inc, Shoreview, Minn, USA) catheter was inserted into the submucosal tunnel and inflated into the mediastinum, leading to deeper injury and mediastinitis.

In the 58-year-old man with esophageal dysphagia, EGD showed spastic contractions in the esophageal body and a tight gastroesophageal junction (GEJ). High-resolution manometry displayed esophagogastric junction outflow obstruction with hypercontractile esophagus. POEM was performed.

We injected saline before mucosal incision was made at 30 cm from the incisors. Then the submucosal tunnel was extended to the gastric side until 44 cm, 2 cm beyond the GEJ.

Myotomy was performed to the circular muscle from 32 to 44 cm, although some longitudinal muscles were lacerated, and a full-thickness defect was seen at some areas. Following completion of myotomy, the EndoFLIP catheter was blindly reinserted into the esophagus. The balloon was inflated to 30 mL but without visualized localization of the GEJ on EndoFLIP readout.

Suspecting that the catheter may be mispositioned, we deflated the balloon and reinserted the endoscope, demonstrating that the EndoFLIP catheter passed through the incision into the submucosal tunnel.

After the catheter was removed, the endoscope was advanced back into the submucosal tunnel, where a large muscular layer defect was seen extending into the mediastinum, suggesting that the balloon had been inflated within the tunnel and expanded into the mediastinum. Some vessels were newly visualized in the submucosal tunnel, which were coagulated.

We then closed the mucosal incision with endoclips. On postoperative day 1, the patient developed chest pain and desaturation. He was febrile with elevated white blood cells. CT scan showed pleural effusion and atelectasis, suggesting mild mediastinitis. We kept the patient nil per os and treated him with antibiotics. Body temperature and white blood cells decreased daily, and mediastinitis improved. Oral diet was slowly reintroduced, and he was discharged on day 6.

Because EndoFLIP allows for real-time evaluation of the lower esophageal sphincter, using it during POEM is increasingly common. However, our case illustrates the potential risk of the EndoFLIP catheter being inserted through the esophageal incision and into the submucosal tunnel, with inflation into the mediastinum.

When using EndoFLIP during POEM, the endoscope should be reinserted prior to balloon inflation to confirm appropriate position of the catheter within the esophageal lumen.

A, Spastic contraction in the esophageal body. B, Barium esophagogram showing spastic contractions and stasis of barium.

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