Functional luminal imaging probe technology to assess response after flexible endoscopic Zenker diverticulotomy.

Zenker diverticulum (ZD) is rare, with an unknown overall prevalence, given that many patients with ZD are likely asymptomatic. ZDs are pseudodiverticula that manifest as mucosal and submucosal pulsion through the Killian triangle. Postulated mechanisms include increased intraesophageal pressure at an area of weakness in the proximal esophageal wall and hypertensive upper-esophageal sphincter (ie, decreased compliance). ZD is frequently diagnosed by esophagography. Symptoms include dysphagia, regurgitation, and, in severe cases, weight loss and malnutrition. Historically, ZD was treated by an open surgical approach, but this has largely been abandoned because of the development of transoral interventions.2, 3 The conventional flexible-endoscopic approach involved dividing the muscularis propria to the base of the diverticulum by using a variety of endoscopic accessories. Li et al described a novel technique to divide the cricopharyngeus (CP) septum after creation of a submucosal tunnel, similar to esophageal peroral endoscopic myotomy (POEM) for the treatment of achalasia, called Zenker POEM (Z-POEM). Outcomes after flexible endoscopic intervention relied on clinical follow-up, which is subjective and not standardized. Recurrence of symptoms may not correlate with the postmyotomy esophagram findings.2, 6 With the advent of functional luminal imaging probe (FLIP) technology (EndoFLIP; Medtronic, Minneapolis, Minn, USA), clinicians can objectively measure luminal cross-sectional area using 16 sensors housed in an electrode-containing balloon along an 8-cm catheter. Upon inflation of the balloon with up to 50 mL of saline solution, the console executes calculations to perform high-resolution impedance planimetry. The result of dividing the cross-sectional area by the intraballoon pressure is the distensibility index (DI). A greater DI should correlate with greater laxity and decreased tone of the surrounding muscle. With EndoFLIP topography, red-colored regions correlate with higher-pressure zones, and blue-colored regions correlate with lower-pressure zones. The main clinical utility of FLIP has been in the esophageal lumen. FLIP gained initial traction in predicting the response to POEM for achalasia. It has been used to assess pyloric responses to botulinum toxin injection for gastroparesis and is being explored in patients undergoing gastric POEM for gastroparesis. Although esophageal diverticular POEM has been described, no objective measurement with reliable correlation to symptom response has been prospectively investigated. To this end, we performed preprocedure and postprocedure FLIP topography in a patient undergoing Z-POEM.

A 91-year-old man presented with classic ZD symptoms, including dysphagia, frequent regurgitation, throat clearing, coughing, and unintentional weight loss of 30 pounds over 1 year. A barium esophagram (Fig. 1) revealed a 5-cm-long ZD. The patient was unfit for surgical intervention because of his advanced age and history of coronary artery disease. He underwent upper endoscopy, which revealed a large ZD (Video 1, available online at www.VideoGIE.org). The diverticular orifice was the dominant pathway (Fig. 2). The FLIP catheter was placed across the CP and inflated sequentially with 40 mL and 50 mL of saline solution. After FLIP measurements (Fig. 3), a gastroscope was passed, and CP myotomy was performed by use of the submucosal tunneling technique (Fig. 4A and B). No intraprocedural adverse events occurred. Before tunnel closure, the FLIP catheter was reinserted and inflated. The diameter and DI improved (Fig. 5). The mucosotomy was closed with hemostatic clips. After hospitalization for 24-hour observation, a postprocedural esophagram (Fig. 6) revealed improvement. One week later, the patient reported complete resolution of all symptoms.

Figure 1

Premyotomy barium esophagram revealing Zenker diverticulum with retention of contrast material.

Figure 2

Zenker diverticulum adjacent to true esophageal lumen. The esophageal lumen is at 12 o’clock, and the diverticular lumen is at 6 o’clock, with the cricopharyngeus seen between them.

Figure 3

Premyotomy functional luminal imaging probe topography at 40 and 50 mL with diameter and distensibility index measurements. The red region was a higher-pressure, less distensible zone at the cricopharyngeus. CSA, Cross-sectional area of lumen; Z-POEM, Zenker peroral endoscopic myotomy.

Figure 4

A, B, Submucosal tunnel created before the myotomy. The esophageal circular muscle is at 12 o’clock, the diverticular submucosa is at 6 o’clock, and the exposed cricopharyngeus seen between them (A). The completed myotomy (B).

Figure 5

Postmyotomy functional luminal imaging probe topography at 40 and 50 mL with diameter and distensibility index measurements. The yellow region was a relatively lower-pressure, more distensible zone at the cricopharyngeus. CSA, Cross-sectional area of lumen; Z-POEM, Zenker peroral endoscopic myotomy.

Figure 6

Postmyotomy barium esophagram revealing improvement in the passage of contrast material through the upper esophagus.

A reliable objective metric to predict clinical response to endoscopic therapy for ZD has not been previously described. We used EndoFLIP to objectively assess improvement in DI and luminal diameter after Z-POEM and showed that this method is technically feasible and safe. These data may be useful in offering a complement to postmyotomy esophagraphy. This method could provide endoscopists with real-time feedback on the adequacy of the myotomy and direct additional intraprocedural intervention, if necessary. Further studies are needed with more patients to determine whether improvement in DI and luminal diameter correlates with immediate clinical response and durable symptom control.

Disclosure

Dr Baker is a consultant for Medtronic. Dr Law is a consultant for Olympus America. All other authors disclosed no financial relationships relevant to this publication.