Melissa M. Ledgerwood

Esophageal distension during bolus transport: can it be detected by intraluminal impedance recordings?

Esophageal multiple intraluminal impedance (MII) measurement has been used to detect gastro‐esophageal reflux and bolus transport. It is not clear if MII can detect changes in luminal cross sectional area (CSA) during bolus transport. Intraluminal ultrasound (US) images, MII, and high resolution manometry (HRM) were recorded simultaneously to determine temporal relationship between CSA and impedance during esophageal bolus transport and to define the relationship between peak distension and nadir impedance.

Circular and longitudinal muscles shortening indicates sliding patterns during peristalsis and transient lower esophageal sphincter relaxation

Esophageal axial shortening is caused by longitudinal muscle (LM) contraction, but circular muscle (CM) may also contribute to axial shortening because of its spiral morphology. The goal of our study was to show patterns of contraction of CM and LM layers during peristalsis and transient lower esophageal sphincter (LES) relaxation (TLESR). In rats, esophageal and LES morphology was assessed by histology and immunohistochemistry, and function with the use of piezo-electric crystals and manometry. Electrical stimulation of the vagus nerve was used to induce esophageal contractions. In 18 healthy subjects, manometry and high frequency intraluminal ultrasound imaging during swallow-induced esophageal contractions and TLESR were evaluated. CM and LM thicknesses were measured (40 swallows and 30 TLESRs) as markers of axial shortening, before and at peak contraction, as well as during TLESRs. Animal studies revealed muscular connections between the LM and CM layers of the LES but not in the esophagus. During vagal stimulated esophageal contraction there was relative movement between the LM and CM. Human studies show that LM-to-CM (LM/CM) thickness ratio at baseline was 1. At the peak of swallow-induced contraction LM/CM ratio decreased significantly (<1), whereas the reverse was the case during TLESR (>2). The pattern of contraction of CM and LM suggests sliding of the two muscles. Furthermore, the sliding patterns are in the opposite direction during peristalsis and TLESR.

Tu1425 The Effects of Body Position on the Bolus Movements, Bolus Shape and Characteristics of Peristalsis

IEP, (c) Baseline wander correction using SBL, (d) Sample 24h in-vivo tracing(every 3rd channel shown), (e) Zoomed baseline regression of channel number 7, (f) Zoomed baseline regression of channel 13, (g) Sample TLESR in the 23rd hour, (h) Baseline wander correction using IEP, (i) Baseline wander correction using SBL, (j) Sample TLESR near the 1st hour, (k) Baseline wander correction using IEP, (l) Baseline wander correction using statistical learning.

Tu1971 Circular & Longitudinal Muscles Slide Against Each Other in Opposite Directions During Peristalsis & Transient Lower Esophageal Sphincter Relaxation

planimetry data from each subject were exported to MATLABTM (The Math Works, Natick, MA). A customized MATLAB program generated a plot (Figure) that included distension volume (bottom panel), 16 channels of diameter changes (middle panel) and intrabag pressure (top panel) over whole study period. The start of reactivity defined by nonpropagating or intermittent contractions and the onset of continuous secondary peristalsis were identified by noting periods of reduced diameter as a surrogate for contraction. The pressure and volume at the onset of these events were measured and compared using nonparametric tests. Results: All healthy subjects had evidence of reactivity and 8 of 10 had secondary peristaltic contractions either lasting to the maximal distension volume (60 ml in 6 subjects) or stopping earlier (35-45 ml in 2 subjects). Thirteen EoE patients had reactivity, but only 7 had secondary peristaltic contractions, few than healthy controls but not reaching statistical significance (see Table). The threshold intrabag pressure values associated with onset of reactivity and onset of secondary peristaltic contractions were significantly higher in the EoE group compared with healthy controls (see Table). The intrabag volumes at onset of reactivity and onset of continuous contractions were also significantly higher in the EoE group (see Table). Conclusions: Patients with EoE require higher intra-esophageal pressures to generate esophageal reactivity and secondary peristalsis when compared with healthy controls. Of the EoE patients who develop reactivity with balloon distention, significantly fewer went on to develop evidence of secondary peristalsis than healthy controls.Whether this difference is associated with known clinical complications of EoE such as food impaction or GERD requires further study.

Mo1233 Functional Evidence for the “Purse String Morphology” of the External Anal Sphincter

tion, in C57Bl6 mice. In vivo water T2 was not different between the NASH mouse model (MCD) and controls (MCS), however, the T2 of liver lipids as well as lipid fractions were significantly elevated in the MCD mice. Ex vivo metabolite profiles could be separated using principle component analysis (PCA) from HR-MAS MRS tissue data. Peaks identified to contribute to the separation of the MCD and the MCS mice, were found to have significant correlations to peaks associated with fatty acids. Our results indicate that non-invasive MRS is a usefull tool in diagnosis NAS as liver-derived lipid transverse relaxation rate values could discriminate the MCD mice from the MCS mice in vivo. The ex vivo HR-MAS results suggested that this could be due to subtle differences in the lipid profiles between the MCD and MCS groups. In conclusion, we report non-invasive in vivo diagnostic approach to NASH in mice. Our results promise translational value for MRS imaging in investigating disparities in lipid profiles in NASH.

Mo2106 Peristaltic Distension of the Esophagus: Detected by Multiple Intraluminal Impedance Measurements

Introduction: Simultaneous manometry and intraluminal ultrasound imaging studies show that similar to contraction wave, distension wave traversing ahead of contraction wave is also peristaltic. Cross sectional area (CSA) of the esophagus is one of the several variables that determine intraluminal esophageal impedance value. Aim: We recorded simultaneous intraluminal US images, impedance and high resolutionmanometry to determine the relationship between esophageal CSA and intraluminal esophageal impedance values. Studies were conducted in 15 normal healthy subjects. Impedance and manometry were measured along the whole length of the esophagus (Sierra Scientific) and US images were recorded at 2 and 12 cm above the LES. Swallow induced primary peristalsis was recorded using 5 ml bolus of 0.5 N saline. Impedance data were exported to Excel and analyzed for the baseline and lowest impedance value at each level. Cross sectional area of the esophagus at 4 and 14 cm of the esophagus were measured from the US images. Results: Impedance recordings show that following a swallow, the onset of drop in impedance as well as nadir impedance traverses the esophagus in a sequential fashion in front of the contraction wave (figure, left panel). There is strong linear relationship between the location and nadir impedance value such that the lowest impedance values are located just above the LES, with a difference of approximately 100 ohms every 1 cm along the length of the esophagus (right panel). Atropine injected intravenously (10 μgm/kg) abolished esophageal contractions, reduced baseline esophageal impedance and abolished sequential progression of nadir impedance along the esophagus). US image analysis shows that peak distension corresponds with nadir impedance value. Similar to nadir impedance, peak distension recorded by US imaging traverses the esophagus in a peristaltic fashion. US images show greater esophageal distension at 4 cm compared to 14 cm above the LES, cross sectional area of 1400 versus 600 mm2 respectively. Conclusion: These data prove: 1) intraluminal distension and contraction wave during peristalsis are tightly linked and 2) intraluminal impedance recording is a relatively simple technique to record luminal distension of the esophagus.