Functional morphology of the lower esophageal sphincter and crural diaphragm determined by three-dimensional high-resolution esophago-gastric junction pressure profile and CT imaging

Abstract

The smooth muscles of the lower esophageal sphincter (LES) and skeletal muscles of the crural diaphragm (CD) provide a closure/antireflux barrier mechanism at the esophago-gastric junction (EGJ). A number of questions in regard to the pressure profile of the LES and CD remain unclear, e.g., ) Why is the LES pressure profile circumferentially asymmetric,) Is the crural diaphragm (CD) contraction also circumferentially asymmetric, and ) Where is the LES and CD pressure profile located in the anatomy of the esophagus and stomach? The three-dimensional (3-D) high-resolution esophageal manometry (HRM) catheter can record a detailed profile of the EGJ pressure; however, it does not allow the determination of the circumferential orientation of individual pressure transducers in vivo. We used computed tomography (CT) scan imaging in combination with 3-D EGJ pressure recordings to determine the functional morphology of the LES and CD and its relationship to the EGJ anatomy. A 3-D-HRM catheter with 96 transducers (12 rings, 7.5 mm apart, located over 9-cm length of the catheter, with eight transducers in each ring, 45° apart (Medtronics), was used to record the EGJ pressure in 10 healthy subjects. A 0.5-mm diameter metal ball (BB) was taped to the catheter, adjacent to of the catheter. The EGJ was recorded under the following conditions: ) end-expiration (LES pressure) before swallow, after swallow, and after edrophonium hydrochloride; and) peak inspiration (crural diaphragm contraction) for tidal inspiration and forced maximal inspiration. A CT scan was performed to localize the circumferential orientation of the BB. The CT scan imaging allowed the determination of the circumferential orientation of the LES and CD pressure profiles. The LES pressure under the three end-expiration conditions were different; however, the shape of the pressure profile was unique with the LES length longer toward the lesser curvature of the stomach as compared with the greater curvature. The pressure profile revealed circular and axial pressure asymmetry, with greatest pressure and shortest cranio-caudal length on the left (close to the angle of His). The CD contraction with tidal and forced inspiration increases pressure in the cranial half of the LES pressure profile, and it was placed horizontally across the recording. The CD, esophagus, and stomach were outlined in the CT scan images to construct a 3-D anatomy of the region; it revealed that the hiatus (CD) is placed obliquely across the esophagus; however, because of the bend of the esophagus to the left at the upper edge of the hiatus, the two were placed at right angle to each other, which resulted in a horizontal pressure profile of the CD on the LES. Our observations suggest a unique shape of the LES, CD, and the anatomical relationship between the two, which provides a possible explanation as to why the LES pressure shows circumferential and axial asymmetry. Our findings have implication for the length and circumferential orientation of myotomy incision required for the ablation of ...

Esophageal A‐ring is associated with the severity of gastroesophageal reflux

“…Mittal et al evaluated the functional morphology of the GEJ using both computed tomography (CT) and threedimensional-high resolution manometry (3-D-HRM). 12 They were able to differentiate the contraction of the crural diaphragm (CD) from the intrinsic lower esophageal sphincter muscle by measuring pressure in the lower esophagus during the respiratory cycle while validating the location of the probe under CT. The end-expiratory GEJ pressure reflected the LES pressure alone and the increase in pressure with tidal and forced inspirations accounted for the contribution of the CD.…”

Tissue engineering of the gastroesophageal junction

“…Advances in high‐resolution, 3D manometry have led to a detailed understanding of the pressure profile in this region. A recent study characterized the pressures averaged across 10 healthy adult patients (Mittal et al, 2017). Similar to other studies, they found that the profiles at the GEJHPZ were not symmetric.…”

“…Right‐most set shows forced inspiration (FI), note change in color scale bar. Reproduced and adapted with permission from Mittal R.K. et al (2017). Functional morphology of the lower esophageal sphincter and crural diaphragm determined by 3D high‐resolution esophagogastric junction pressure profile and CT imaging , American Journal of Physiology ‐ Gastrointestinal and Liver Physiology , 313(3): G212‐G219.…”

Esophageal physiology—an overview of esophageal disorders from a pathophysiological point of view

“…The CD consists of the right and left crus, and the right crus consists of left and right arms, which wrap around the distal esophagus. 39 The esophagus is also angulated to the left just cephalad to where it joins the stomach, forming the angle of His. 39 The intraluminal extension of the angle of His creates an anatomic structure known as the gastroesophageal flap valve, which is graded at retroflexion during upper endoscopy.…”