An extended proximal esophageal myotomy is necessary to normalize EGJ distensibility during Heller myotomy for achalasia, but not POEM

Abstract

Background: For laparoscopic Heller myotomy (LHM), the optimal myotomy length proximal to the esophagogastric junction (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 with FLIP after each operative step. During LHM and POEM, each patient's myotomy was performed in two stages: first, a myotomy ablating only the EGJ complex was created (EGJ-M), extending from 2 cm proximal to the EGJ, to 3 cm distal to it. Next, the myotomy was lengthened 4 cm further cephalad to create an extended proximal myotomy (EP-M).

Results: Measurements were performed in 12 patients undergoing LHM and 19 undergoing POEM. LHM resulted in an overall increase in DI (1.6 ± 1 vs. 6.3 ± 3.4 mm(2)/mmHg, p < 0.001). Creation of an EGJ-M resulted in a small increase (1.6-2.3 mm(2)/mmHg, p < 0.01) and extension to an EP-M resulted in a larger increase (2.3-4.9 mm(2)/mmHg, p < 0.001). This effect was consistent, with 11 (92%) patients experiencing a larger increase after EP-M than after EGJ-M. Fundoplication resulted in a decrease in DI and deinsufflation an increase. POEM resulted in an increase in DI (1.3 ± 1 vs. 9.2 ± 3.9 mm(2)/mmHg, p < 0.001). Both creation of the submucosal tunnel and performing an EGJ-M increased DI, whereas lengthening of the myotomy to an EP-M had no additional effect. POEM resulted in a larger overall increase from baseline than LHM (7.9 ± 3.5 vs. 4.7 ± 3.3 mm(2)/mmHg, p < 0.05).

Conclusions: During LHM, an EP-M was necessary to normalize distensibility, whereas during POEM, a myotomy confined to the EGJ complex was sufficient. In this cohort, POEM resulted in a larger overall increase in EGJ distensibility.

Figure 1

The stepwise myotomy creation during a laparoscopic Heller myotomy is shown here. First, a sterile ruler, with notches cut at 1 cm increments, is used to measure from 2 cm proximal to the esophagogastric junction (EGJ), to 3 cm distal to it (panel A). An EGJ-myotomy is then created between these two points (panel B). This myotomy is then lengthened 4 cm proximally to create the final extended proximal (EP) myotomy (panel C). The arrow points to the location of the EGJ in panels B and C.

Figure 2

FLIP measurements taken after each step of a POEM procedure: induction of anesthesia, creation of the submucosal tunnel, creation of an EGJ myotomy, and subsequent lengthening to an extended proximal (EP) myotomy. The primary outcome measure of distensibility index (DI) is calculated by dividing the minimum cross-sectional area (CSA) at the EGJ by intra-bag pressure.

Figure 3

Stepwise changes in EGJ distensibility index (DI) are shown over the subsequent steps of laparoscopic Heller myotomy (LHM), measured at a 40 ml distension volume. Creation of pneumoperitoneum and hiatal dissection had no effect on DI. Creation of an EGJ myotomy resulted in a small but significant increase and extension of the myotomy to an extended proximal (EP) myotomy resulted in a larger increase. Partial fundoplication then resulted in a decrease in DI and final deinsufflation of pneumoperitoneum an increase.

Figure 4

Stepwise changes in EGJ distensibility index (DI) are shown over the subsequent steps of POEM, measured at a 40 ml distension volume. Creation of the submucosal tunnel and performing an EGJ myotomy both increased DI, whereas lengthening to an extended proximal myotomy had no added effect.