The purpose of this study is to learn about the safety and usefulness of a procedure called endoscopic submucosal myotomy, which is a new technique in the treatment of achalasia. Achalasia is a disorder involving the lack of smooth muscle relaxation and sustained high pressure in the sphincter (muscle) of the lower esophagus. This may result in symptoms such as difficulty in swallowing, chest pain, regurgitation of food and eventually, weight loss.

For more than a decade, a laparoscopic surgical procedure known as Heller myotomy has been the primary treatment for achalasia in patients with low surgical risk. In Heller myotomy, the surgeon makes three to four small abdominal incisions, inserts tube-like instruments through them, and once inside, the junction between the esophagus and stomach is found, a lengthwise incision is made on the muscular ring surrounding the lower esophageal sphincter which weakens the muscle and the lower esophageal sphincter or muscle (LES) is then able to open more easily. However, there is an emerging field known as natural orifice (opening) transluminal (through the lumen) endoscopic surgery (NOTES). This approach involves passing an endoscope - a thin tube with a built-in camera, light and minuscule tools through the natural opening in the body, like the mouth in order to perform less invasive surgery without any external wounds or scars. The procedure is done using the Submucosal Endoscopy with Mucosal Flap (SEMF) technique which involves passing an endoscope through the mouth into the esophagus, where a small incision is made on the lining of the esophagus, known as the mucosa. A balloon is then inserted and dilated in the submucosa - the layer between the inner lining of the esophagus and the outer wall consisting of the muscle of the esophagus. Dilation of the balloon in the submucosa creates a tunnel that allows insertion of the endoscope and access to the muscle of the lower esophageal sphincter (LES). A long incision is then carefully made on the posterior portion of the muscular ring that forms the LES. The incision divides the muscle fibers of the LES, which weakens the muscle, allowing for the easier passage of food while preserving some valve function to prevent reflux of acid from the stomach into the esophagus.

The expected duration of participation is up to 10 years from the time study participants undergo the endoscopic surgical procedure.

The safety of the procedure and feasibility of the study will be measured by improvement in subjects' symptoms score, decrease in LES pressure, as well as the number and severity of complications or adverse events experienced by the subjects. A modified Eckhardt dysphagia assessment tool will be used in grading the dysphagia symptoms.

Inclusion Criteria:

1. Patients 18 years or older, male or female, belonging to any race or ethnic origin
2. Patients with manometric positive diagnosis of achalasia, with corresponding symptoms of dysphagia, regurgitation of food or chest pain
3. Patients who are willing and competent to sign Informed Consent and to comply with study related visits and procedures

Exclusion Criteria:

1. Patients who are below 18 years of age
2. Presence of coagulopathy
3. Pregnancy
4. Patients who, in the investigator's opinion, are medically unstable, are unable to give informed consent, or whose risks outweigh the benefits of participating in the study
5. Vulnerable subjects: Prisoners, persons with decisional incapacity, and any person who are directly involved in the study, including their immediate family members, and anybody who may have any conflict of interest such as employees of ERBE, USA.