Volume 134, Issue 5, Pages 1322-1331 (May 2008) A Unique Longitudinal Muscle Contraction Pattern Associated With Transient Lower Esophageal Sphincter Relaxation  Arash Babaei, Valmik Bhargava, Hariprasad Korsapati, Wei Hao Zheng, Ravinder K. Mittal  Gastroenterology  Volume 134, Issue 5, Pages 1322-1331 (May 2008) DOI: 10.1053/j.gastro.2008.02.031 Copyright © 2008 AGA Institute Terms and Conditions

Figure 1 Schematic of the parameters measured to determine the temporal correlation between the circular and longitudinal muscle contraction of the esophagus during swallow-induced esophageal peristalsis (A) and transient LES relaxation (B). LMC, longitudinal muscle contraction; CMC, circular muscle contraction; SLESR, swallow-induced lower esophageal sphincter relaxation; TLESR, transient lower esophageal sphincter relaxation; CDI, crural diaphragm inhibition; CC, common cavity pressure. Gastroenterology 2008 134, 1322-1331DOI: (10.1053/j.gastro.2008.02.031) Copyright © 2008 AGA Institute Terms and Conditions

Figure 2 Temporal relationship between pressure wave and longitudinal muscle contraction in the esophagus and LES relaxation. Pressures and ultrasound images in the esophagus were recorded at the 7-cm site above the LES. Gastroenterology 2008 134, 1322-1331DOI: (10.1053/j.gastro.2008.02.031) Copyright © 2008 AGA Institute Terms and Conditions

Figure 3 Longitudinal muscle contraction at 7, 12, and 17 cm above the LES during SLESR. (A) Swallow induced changes in the muscle thickness and pressure wave. *P < .001. (B) Note that the duration of longitudinal muscle contraction is longer than the circular muscle contraction. *P ≤ .01. Gastroenterology 2008 134, 1322-1331DOI: (10.1053/j.gastro.2008.02.031) Copyright © 2008 AGA Institute Terms and Conditions

Figure 4 Temporal correlation between longitudinal muscle contraction at the 7-, 12-, and 17-cm sites and TLESR. Respiration-related changes in muscle thickness were digitally filtered in these records. (A) Note that, at 7 cm, the LMC starts slowly before the onset of LES relaxation and then accelerates during the TLESR. The LMC lasts during the entire period of TLESR. Also note a close temporal correlation between the increase in esophageal pressure (common cavity pressure) and accelerated LMC during TLESR. (B) Note that, at the 12-cm level, LMC starts after the onset of LES relaxation and lasts until end of TLESR. Also note a close temporal correlation between the increase in esophageal pressure (common cavity pressure) and the LMC during TLESR. (C) Note a decrease in the muscle thickness during the TLESR at 17-cm site. Gastroenterology 2008 134, 1322-1331DOI: (10.1053/j.gastro.2008.02.031) Copyright © 2008 AGA Institute Terms and Conditions

Figure 5 Longitudinal muscle contraction at 7, 12, and 17 cm above the LES during TLESR. (A) Note that the average and peak muscle thickness are significantly greater at the 7- and 12-cm and smaller at 17-cm site, as compared with the baseline. *P < .001; †P < .01. (B) Note that the duration of LMC at the 7-cm site is longer than duration of TLESR, but, at the 12-cm site, it is significantly shorter. *P < .0001; †P < .01. (C) Note that the time lag between the esophageal contraction and LES relaxation increases significantly distally during SLESR. The LM event (LMC) at the 7-cm site occurs prior to the onset of TLESR. *P < .05; †P < .001. Gastroenterology 2008 134, 1322-1331DOI: (10.1053/j.gastro.2008.02.031) Copyright © 2008 AGA Institute Terms and Conditions

Figure 6 Relationship among common cavity pressure, TLESR, and gastroesophageal reflux as detected by impedance recordings of the esophagus. (A) Note that the onset of common cavity pressure begins at the onset of LES relaxation. Also note that the change in impedance occurred much later than the onset of common cavity pressure. (B) Note that the onset of common cavity pressure begins at the onset of LES relaxation and that the peak esophageal pressure during common cavity is higher than the gastric pressure. All pressures are referenced to atmospheric pressure (0 pressure line). Also note that there is no significant change (>50%) in impedance during the TLESR. However, a 10% drop in impedance has been marked as reflux and still lags significantly behind the common cavity. Gastroenterology 2008 134, 1322-1331DOI: (10.1053/j.gastro.2008.02.031) Copyright © 2008 AGA Institute Terms and Conditions

Figure 7 Gastroesophageal pressure gradients before the onset of TLESR, at the onset of gastroesophageal reflux, and at the peak of common cavity pressure in the esophagus: Note a decrease in the pressure gradient at the onset of reflux. At the peak of common cavity pressure in the esophagus, there is a reversal of pressure gradient in the direction of stomach. †P < .001. Gastroenterology 2008 134, 1322-1331DOI: (10.1053/j.gastro.2008.02.031) Copyright © 2008 AGA Institute Terms and Conditions

Figure 8 Schematic of the patterns of longitudinal muscle contraction during peristalsis and transient lower esophageal relaxation. Peristaltic contraction is associated with an aborally traversing simultaneous contraction of the circular and longitudinal muscle of the esophagus. On the other hand, transient lower esophageal sphincter relaxation is associated with a retrograde contraction of the longitudinal muscle of the distal esophagus, in the absence of circular muscle contraction. Gastroenterology 2008 134, 1322-1331DOI: (10.1053/j.gastro.2008.02.031) Copyright © 2008 AGA Institute Terms and Conditions