Volume 128, Issue 2, Pages 487-497 (February 2005) Sensory and motor function of the esophagus: Lessons from ultrasound imaging  Ravinder K. Mittal, Jianmin Liu, James L. Puckett, Vikas Bhalla, Valmik Bhargava, Neelish Tipnis, Ghassan Kassab  Gastroenterology  Volume 128, Issue 2, Pages 487-497 (February 2005) DOI: 10.1053/j.gastro.2004.08.004 Copyright © 2005 American Gastroenterological Association Terms and Conditions

Figure 1 B-mode ultrasonographic images of the lower esophageal sphincter (LES) with the transducer positioned in the center of the LES. (A) Baseline LES (note asymmetrical geometry); (B) postrelaxation contraction of the LES (note the relatively more symmetrical circular geometry and thickened muscle layers). The circle in the center represents the ultrasound transducer (T). MUC, mucosa; CM, circular muscle (the intermuscular septum is between the circular and longitudinal muscle layers); LM, longitudinal muscle (outside the LM layer is the adventia); SP, spine; A, anterior; P, posterior; L, left; R, right. Gastroenterology 2005 128, 487-497DOI: (10.1053/j.gastro.2004.08.004) Copyright © 2005 American Gastroenterological Association Terms and Conditions

Figure 2 B-mode ultrasonographic images of the esophagus; the transducer is positioned 5 cm above the lower esophageal sphincter. (A) Baseline esophagus (before swallow; note the asymmetrical slitlike geometry). (B) Esophagus at the peak of contraction (note the symmetrical circular geometry and thickened muscle layers). The circle in the center represents the ultrasound transducer (T). MUC, mucosa; CM, circular muscle (the intermuscular septum is between the circular and longitudinal muscle layers); LM, longitudinal muscle (outside the LM layer is the adventia); AO, aorta; A, anterior; P, posterior; L, left; R, right. Gastroenterology 2005 128, 487-497DOI: (10.1053/j.gastro.2004.08.004) Copyright © 2005 American Gastroenterological Association Terms and Conditions

Figure 3 Temporal correlation between intraluminal pressure and muscle thickness during a swallow-induced contraction: esophageal pressure and muscle thickness during a 5-mL water swallow are shown in this figure. The increase in intraluminal pressure is associated with an increase in thickness of both the circular and longitudinal muscles. LM, longitudinal muscle; CM, circular muscle. Gastroenterology 2005 128, 487-497DOI: (10.1053/j.gastro.2004.08.004) Copyright © 2005 American Gastroenterological Association Terms and Conditions

Figure 4 Schematics of the effects of circular and longitudinal muscle contraction on the muscle thickness and muscle cross-sectional area (CSA), based on the law of mass conservation. (A) During circular muscle contraction, the initial CSA (CSAO) is equivalent to the final CSA (CSAF), and there is an increase in the muscle thickness. (B) Conversely, during longitudinal muscle contraction, shortening of the esophagus (LF > LO) results in an increase in muscle thickness and an increase in the muscle CSA (CSAF > CSAO). Volume being constant, there is an inverse relationship between the degree of longitudinal shortening and the change in muscle CSA. WTo, well-thickness initial; WTF, well-thickness final. Gastroenterology 2005 128, 487-497DOI: (10.1053/j.gastro.2004.08.004) Copyright © 2005 American Gastroenterological Association Terms and Conditions

Figure 5 Temporal variation in muscle cross-sectional area (Amus/A*mus) and intraluminal pressure (A) and average radius to circular muscle and total muscle thickness (B) averaged over 8 swallows. The bars indicate SD. The horizontal dotted lines indicate the resting state values: A*mus and P* (A) and R*in and *mus (B). The vertical dotted lines were chosen to match features in the 2 panels. Amus, muscle area; A*mus, baseline muscle area; P*, baseline intraluminal pressure; R*in, baseline radius to circular muscle; *mus, muscle thickness. Gastroenterology 2005 128, 487-497DOI: (10.1053/j.gastro.2004.08.004) Copyright © 2005 American Gastroenterological Association Terms and Conditions

Figure 6 M-mode echoesophagograph with a superimposed intraesophageal pressure and muscle cross-sectional area (MCSA) during a 5-mL water swallow; the transducer is positioned 2 cm above the lower esophageal sphincter. A, baseline esophagus, before/after swallow; B, bolus-induced distention, bolus pressure, and thinning of mucosa and muscle layers; C, esophageal contraction. Note the dissociation between the increase in MCSA and the increase in intraluminal pressure. The increase in MCSA (—○—) begins before and outlasts the intraluminal pressure wave (——). The difference between the onset of CSA and pressure (x) is likely to be due to the delay in recording pressure (circular muscle contraction) by manometry. LM, longitudinal muscle; CM, circular muscle; y = time lag between return of pressure and MCSA to baseline. Gastroenterology 2005 128, 487-497DOI: (10.1053/j.gastro.2004.08.004) Copyright © 2005 American Gastroenterological Association Terms and Conditions

Figure 7 Ultrasound images of the lower esophageal sphincter (LES) and esophageal body in healthy subjects and patients with high-amplitude esophageal contractions (HAEC), diffuse esophageal spasm (DES), and achalasia of the esophagus. The LES image is from the center of the LES. The esophageal images are from a time when there was no esophageal contractile activity, which was observed through manometry. Note the differences in the muscle thickness in 4 subjects, with the thickest muscle in patients with achalasia of the esophagus. Gastroenterology 2005 128, 487-497DOI: (10.1053/j.gastro.2004.08.004) Copyright © 2005 American Gastroenterological Association Terms and Conditions

Figure 8 Sustained esophageal contraction associated with chest pain. Esophageal pH (A), distal esophageal pressure (B), and esophageal smooth muscle thickness (C) are shown during a 2.5-minute recording interval. The onset of chest pain is depicted by the vertical line (time 0). The onset of sustained esophageal contraction occurs approximately 120 seconds before the onset of pain. The pressure record shows 2 small contractions (arrows) that are accompanied by brief increases in esophageal muscle thickness during the sustained esophageal contraction. Gastroenterology 2005 128, 487-497DOI: (10.1053/j.gastro.2004.08.004) Copyright © 2005 American Gastroenterological Association Terms and Conditions

Figure 9 Heartburn episode without acid reflux associated with sustained esophageal contraction (SEC). The onset of SEC occurred approximately 54 seconds before the onset of heartburn. Note that phasic contractions of the esophagus were associated with an additional increase in the thickness of esophageal wall during sustained esophageal contraction. Gastroenterology 2005 128, 487-497DOI: (10.1053/j.gastro.2004.08.004) Copyright © 2005 American Gastroenterological Association Terms and Conditions

Figure 10 (A) Schematics of the catheter assembly for studying biomechanics of the esophageal wall. (B) Esophageal ultrasound (US) image during distention. (C) Schematic of the measurement of luminal cross-sectional area (CSA), the circumferential length of the esophagus (l), and mean wall thickness (average over the length of the 4 double-headed arrows). Gastroenterology 2005 128, 487-497DOI: (10.1053/j.gastro.2004.08.004) Copyright © 2005 American Gastroenterological Association Terms and Conditions

Figure 11 The patterns of esophageal luminal contents during transient lower esophageal sphincter relaxations: (A) no luminal opening, (B) opening with only predominant liquid, (C) opening with predominant liquid followed by air, (D) opening with predominant air followed by liquid, and (E) opening with predominant air only. The shaded area shows the period of luminal opening. Gastroenterology 2005 128, 487-497DOI: (10.1053/j.gastro.2004.08.004) Copyright © 2005 American Gastroenterological Association Terms and Conditions