Doctors Perform Novel POP Procedure to Treat Gastroparesis

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Gastroparesis is a condition that results in delayed stomach emptying. Patients usually present with symptoms that include pain, bloating, nausea, early satiety and vomiting. While dietary modifications and medical management have been the mainstay of treatment, many patients remain unsatisfied.

"The problem is there are no good medications," says Kumar Krishnan, MD, gastroenterologist in the Division of Gastroenterology at Massachusetts General Hospital. "The most common medication is metoclopramide, which cannot be used long term because of the risk of side effects. Erythromycin can sometimes improve gastric emptying, but its efficacy is limited."

Surgical interventions have similar limitations. Total gastrectomy is an aggressive treatment for a condition that often affects young people while gastric pacemakers have limited efficacy and availability. Gastric and intestinal feeding tubes often negatively affect quality of life.

"For many years, surgeons have struggled to find an option for these patients with the right risk/benefit profile." says Elan Witkowski, MD, MS, minimally invasive surgeon in the Mass General Department of General and Gastrointestinal Surgery. "Options have run the gamut from laparoscopic pacemaker insertion or pyloroplasty, all the way to total gastrectomy which can require multiple days in the hospital. As you add complexity, the risk of complications goes up substantially. Since none of these surgeries are guaranteed to work, most surgeons are appropriately hesitant to offer operations."

Together, Dr. Krishnan and Dr. Witkowski are now performing per-oral pyloromyotomy (POP)—a minimally invasive treatment that is proving to be a potent alternative to current methods for the relief of gastroparesis symptoms. "This is a novel and seemingly very effective treatment," says Dr. Krishnan. "While it is not a cure for gastroparesis, it is a tool in the overall broad management of it."

Implementing Per-Oral Pyloromyotomy at Mass General

During the POP procedure, surgeons open the pylorus so food and other contents can empty out of the stomach more easily. They use an endoscopic approach through the mouth, which avoids the need for an incision.

"During the procedure, a flexible scope is passed through the mouth while the patient is asleep under anesthesia," says Dr. Witkowski. "Tiny instruments on the tip of the scope are then used to elevate and open the lining of the stomach, and then cut the pylorus muscle. Once the muscle is cut, we clip the lining closed and remove the scope."

"It's substantially less invasive than an open surgery," says Dr. Krishnan. "In many of our patients, we do it in about 30 minutes. The anesthetic time is substantially less. Every single patient we've done has been discharged the next day."

According to Drs. Krishnan and Witkowski, ideal POP candidates have a confirmed gastroparesis diagnosis whose predominant symptoms are early satiety, nausea and vomiting. "We try to avoid patients whose primary symptom is intestinal pain because it can be caused by many different things," says Dr. Krishnan. "It's difficult for us to know if that's going to be improved by cutting a muscle."

To determine if a patient fits these criteria, Mass General's motility group administers tests including gastric emptying studies, fluoroscopic examinations and a "smart" pill motility testing system: a functional assessment of gastrointestinal (GI) motility. They also utilize a novel process for assessing pyloric function and distensibility using a newer device called endolumenal functional lumen imaging probe.

"We want to capture those patients who have pylorospasm as a primary mechanism for their gastroparesis," says Dr. Krishnan. "We suspect that those are the patients who are going to respond the best to this."

Drs. Krishnan and Witkowski performed their first POP procedure on March 1, 2019. They have since performed more than 12 additional successful procedures.

"We are seeing improved food tolerance, decreased nausea, decreased vomiting and improvement in early satiety," says Dr. Krishnan. "It's difficult to determine how well these patients will do long term. But the short-term outcome is that most have noticed an improvement."

Investigating New Applications for the POP Procedure

Dr. Krishnan anticipates that the POP procedure will become the primary intervention for gastroparesis, improving the lives of hundreds of thousands of patients.

"We're now reserving these for refractory patients who are in and out of the hospital and on a lot of medications," he says. "But it is a straightforward, streamlined procedure that should probably be transitioned to healthier patients who could substantially improve their quality of life.

Physicians in Mass General's Digestive Healthcare Center are also looking at other novel research applications of the POP procedure, including the use of advanced imaging to study the pylorus and pyloric function. Historically, it has not been easy to biopsy the pylorus, so physicians and researchers don't know why it is dysfunctional in patients with gastroparesis.

"Really understanding why these patients get this condition is an area of substantial interest," says Dr. Krishnan. "The fact that we can get to the pyloric muscle will perhaps provide a conduit for us to understand that a little bit better."

The POP procedure is just one example of the increasing convergence between gastroenterology and gastrointestinal surgery. Mass General clinicians are continuously moving in the direction of hybrid technologies and procedures to provide safer, more effective interventions.

"What's the difference between a minimally invasive surgeon and an advanced endoscopist? Those lines are becoming blurred. That's the benefit of having the Digestive Healthcare Center: We're seeing these different fields come together," says Dr. Krishnan. "We've taken on the approach of working very collaboratively. We're only going to see this model more as it blossoms and grows."

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