Per-oral endoscopic myotomy (POEM) is a minimally invasive therapy for achalasia. The procedure has demonstrated high technical and clinical success with lower adverse events. Different types of knives have been used for cutting and coagulation during the procedure; however, exchanging accessories is sometimes needed to perform all the stages of POEM.

To overcome this disadvantage, the investigators aim to evaluate a single device that integrates in its tip bipolar radiofrequency and microwave, the Speedboat Ultraslim (Creo Medical, UK) for cutting and coagulation during POEM procedure. Some of the promise's advantages derived from its use are: (1) less inflammation, (2) clear differentiation between layers, (3) the use of a single device for the procedure.

This single-center, prospective, interventional study will include patients with achalasia submitted to POEM procedure, with or without fundoplication (POEM-F). All stages (mucosal incision, submucosal tunneling, myotomy) of POEM will be performed using the Speedboat ultraslim flexible catheter. Technical and clinical success, along with safety will be the primary endpoints; while, post-procedure reflux symptoms and quality of life will be assessed as secondary outcomes with reflux severity index (RSI) and the Northwestern Esophageal Quality of Life (NEQOL), respectively.

Achalasia is characterized by the absence of esophageal peristalsis and the inability of the lower esophageal sphincter (LES) to relax. To date, the therapies with higher success rates are the Heller myotomy and the minimally invasive per-oral endoscopic myotomy (POEM). Different tools have been developed for the different POEM stages (mucosal incision, submucosal tunneling, myotomy, and closure). However, some devices need exchanging accessories for cutting and coagulation.

In light of the above, the investigators aim to evaluate a newly launched ultra-slim flexible catheter, Speedboat Ultraslim (Creo Medical, UK) that integrates bipolar radiofrequency (RFA) energy and microwave in its tip for cutting and coagulation, respectively, in patients with achalasia. Some proposed advantages of using this device during POEM are (1) less inflammation and better healing process derived from localized bipolar energy; (2) a protective full that facilities clear differentiation between muscular and mucosal layers; (3) the use of a single device to complete the POEM procedure.

After completing the inclusion criteria, the patients with achalasia will undergo POEM (anterior or posterior incision) with or without fundoplication (F-POEM). The procedures will be performed by previously trained expert endoscopist. The mucosal incision, submucosal tunneling and cutting will be performed using RFA energy, while coagulation will be performed with microwave, both integrated in the tip of the Ultraslim Speedboat.

Technical and clinical success along with safety will be the primary outcomes; while post-procedure reflux symptoms and quality of life will be assessed as secondary outcomes with reflux severity index (RSI) along with endoscopic and pH studies; and the Northwestern Esophageal Quality of Life (NEQOL), respectively.

Inclusion Criteria:

• Patients with 18 years of age or older.
• Patients referred to the participating center (IECED) with a clinical diagnosis of achalasia with an indication for POEM, including previously failed Heller myotomy, balloon dilation or POEM
• Patients who provide informed consent.

Exclusion Criteria:

• Patients who have contraindications for esophagogastroduodenoscopy (EGD).
• Patients with an Eckardt score < 3 before POEM.
• Positive diagnosis of Chagas disease.
• Patients unable to withstand general anesthesia.
• Pregnancy and lactation.
• Barret's esophagus.