The Effect of Differential Proximal Myotomy Length On Esophagogastric Junction Distensibility During Heller Myotomy and Poem

Ezra N Teitelbaum, MD, Nathaniel J Soper, MD, Lubomyr Boris, BS, Frederic Nicodeme, MD, Peter J Kahrilas, MD, John E Pandolfino, MD, Eric S Hungness, MD. Northwestern University Feinberg School of Medicine.

INTRODUCTION: For laparoscopic Heller myotomy (LHM), it has been shown that a myotomy extending 3cm distal to the esophagogastric junction (EGJ) results in superior physiologic and clinical outcomes when compared with a distal segment that is shorter than 2cm. However, the optimal length of the myotomy proximal to the EGJ is unknown. In this study, we used a functional lumen imaging probe (FLIP) to measure EGJ distensibility changes resulting from variable proximal myotomy lengths during LHM and peroral esophageal myotomy (POEM).

METHODS: Distensibility index (DI) (defined as the minimum cross-sectional area at the EGJ divided by pressure) was measured intraoperatively with FLIP (distension volume of 30ml) in patients undergoing LHM and POEM for treatment of achalasia. Measurements were taken after each operative step. Additionally, during both LHM and POEM, each patient’s myotomy was performed in two stages: first, a myotomy across the EGJ with a short proximal (SP) segment was created, extending from 2cm proximal to the EGJ to 3cm distal to the EGJ (5cm total length). After SP myotomy creation, a FLIP measurement was taken. Next, the myotomy was extended 4cm cephalad to create a long proximal (LP) segment, and thus a total myotomy length of 9cm (from 6cm proximal to 3cm distal to the EGJ), and another FLIP measurement was taken. Myotomy lengths were measured using a sterile ruler during LHM and via scope shaft markings during POEM. DI before and after each operative step was compared using a paired t-test.

RESULTS: Six LHM and 16 POEM patients underwent intraoperative FLIP measurements with stepwise proximal myotomy extension. LHM caused an overall increase in DI (2.0 ±1.8 vs. 6.4 ±3.9 mm2/mmHg, p=.02). During LHM, the steps of insufflation of pneumoperitoneum and hiatal dissection did not affect DI. Similarly, creation of a SP myotomy across the EGJ did not alter DI (pre 1.2 ±0.4 vs. post 1.4 ±1.1 mm2/mmHg, p=ns). After LP myotomy extension, DI increased (1.4 ±1.1 vs. 4.4 ±1.7 mm2/mmHg, p<.01). Creation of a partial fundoplication resulted in a non-significant decrease in DI (4.4 ±1.7 vs. 3.2 ±2.4 mm2/mmHg, p=ns). Final deinsufflation of pneumoperitoneum caused an increase in DI (3.2 ±2.4 vs. 6.4 ±3.9 mm2/mmHg, p=.001). POEM resulted in an overall increase in DI (1.9 ±1.4 vs. 9.5 ±4.5 mm2/mmHg, p<.01). During POEM, creation of the submucosal tunnel caused an increase in DI (1.9 ±1.4 vs. 7.1 ±6.8 mm2/mmHg, p<.01). Creation of a SP myotomy caused an increase in DI (7.1 ±6.8 vs. 7.9 ±3.2 mm2/mmHg, p=.02) and extension to a LP myotomy caused an additional increase (7.9 ±3.2 vs. 9.5 ±4.5 mm2/mmHg, p=.001). POEM resulted in a larger overall increase in DI than LHM at a trend level (7.7 ±3.7 vs. 4.5 ±2.5 mm2/mmHg, p=.07).

CONCLUSIONS: During LHM, creation of a myotomy across the EGJ with a 2cm proximal component did not affect DI, and an additional 4cm proximal extension was required to increase distensibility. During POEM, a LP myotomy further increased DI, but a 2cm proximal component may be sufficient to normalize EGJ distensibility.

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