Pressure morphology of the relaxed lower esophageal sphincter: the formation and collapse of the phrenic ampulla

Abstract

Kwiatek MA, Nicodème F, Pandolfino JE, Kahrilas PJ. Pressure morphology of the relaxed lower esophageal sphincter: the formation and collapse of the phrenic ampulla. Am J Physiol Gastrointest Liver Physiol 302: G389 -G396, 2012. First published November 23, 2011 doi:10.1152/ajpgi.00385.2011.-This study aimed to apply novel high-resolution manometry with eight-sector radial pressure resolution (3D-HRM technology) to resolve the deglutitive pressure morphology at the esophagogastric junction (EGJ) before, during, and after bolus transit. A hybrid HRM assembly, including a 9-cm-long 3D-HRM array, was used to record EGJ pressure morphology in 15 normal subjects. Concurrent videofluoroscopy was used to relate bolus movement to pressure morphology and EGJ anatomy, aided by an endoclip marking the squamocolumnar junction (SCJ). The contractile deceleration point (CDP) marked the time at which luminal clearance slowed to 1.1 cm/s and the location (4 cm proximal to the elevated SCJ) at which peristalsis terminated. The phrenic ampulla spanned from the CDP to the SCJ. The subsequent radial and axial collapse of the ampulla coincided with the reconstitution of the effaced and elongated lower esophageal sphincter (LES). Following ampullary emptying, the stretched LES (maximum length 4.0 cm) progressively collapsed to its baseline length of 1.9 cm (P Ͻ 0.001). The phrenic ampulla is a transient structure comprised of the stretched, effaced, and axially displaced LES that serves as a "yield zone" to facilitate bolus transfer to the stomach. During ampullary emptying, the LES circular muscle contracts, and longitudinal muscle shortens while that of the adjacent esophagus reelongates. The likely LES elongation with the formation of the ampulla and shortening to its native length after ampullary emptying suggest that reduction in the resting tone of the longitudinal muscle within the LES segment is a previously unrecognized component of LES relaxation. esophageal manometry; peristalsis; esophageal bolus transit; lower esophageal sphincter FORMATION OF THE PHRENIC AMPULLA initiates the final phase of bolus transit through the esophagus. The globular-shaped ampulla forms at the caudal end of the esophagus in conjunction with transient esophageal shortening resultant from deglutitive contraction of the longitudinal muscle (4,7,19). The bolus is then emptied from the ampulla into the subdiaphragmatic stomach. Ampullary emptying is mechanistically distinct from peristalsis in that luminal clearance is slower and the bolus flow across the hiatus is driven by a sustained hydrostatic pressure rather than a propagated (peristaltic) contraction (13). Videofluoroscopy synchronized with manometry has been invaluable in analyzing the mechanics of ampullary emptying. Correlation between fluoroscopy and manometry is facilitated by placement of mucosal endoclips to mark landmarks such as the squamocolumnar junction (SCJ). The formation of the ampulla can be visualized videofluoroscopically and related to the intraluminal pressures in the tubul...

Esophagogastric Junction pressure morphology: comparison between a station pull‐through and real‐time 3D‐HRM representation

“…Although the pressure attributable to the intrinsic LES would not be expected to vary substantially in synchrony with either respiratory or vascular pulsations, it was strongly influenced by deglutition, exhibiting both deglutitive relaxation and a profound post-deglutitive contraction (10,11). We utilized the post-deglutitive contraction to verify the pressure signature of the LES in the 3D-HRM recording (Figures 4A & 4B).…”

The four phases of esophageal bolus transit defined by high-resolution impedance manometry and fluoroscopy

“…The fourth phase of bolus transit (ampullary emptying) extends from the CDP to the end of the swallow. The CDP is an important pressure topography landmark because it represents the end of the nonsphincteric esophagus and is anatomically in close proximity with the muscular contractile A-ring or proximal aspect of the esophageal vestibule (10,11,16). Although the IBP was significantly lower during phases I, II, and IV in the upright swallows, it was most obvious in phase IV.…”

“…A second transition point along the wavefront, the contractile deceleration point (CDP) occurs at the distal margin of the third topographic esophageal segment identifiable by profound slowing of the wavefront (16). Simultaneous fluoroscopy and endoscopic clipping of the squamocolumnar junction suggest that this landmark represents the time at which propagation decelerates and the peristaltic contraction converges with the proximal aspect of the relaxed, effaced, and elongated lower esophageal sphincter (LES) (11). Morphologically, this represents the phrenic ampulla, and emptying during this phase is not associated with peristaltic stripping but occurs via a distinct mechanism that is more akin to a distended balloon returning to its zero state in conjunction with a shift from inhibitory to excitatory tone of the LES in conjunction with esophageal reelongation.…”

The Spectrum of Achalasia: Lessons From Studies of Pathophysiology and High-Resolution Manometry

“…18 Hence, detailed assessment of postdeglutitive LES opening shows that this is associated with both radial effacement and elongation to form a structure referred to radiographically as the phrenic ampulla. 42 It has also been proposed that a primary stimulus for deglutitive LES relaxation is contraction of the more proximal longitudinal muscle 43,44 and that the longitudinal muscle within the LES itself then relaxes, serving as a yield zone to accommodate the resultant shortening. 45,46 …”