title: Characterization of Esophageal Physiology Using Mechanical State Analysis.
abstract: The esophagus functions to transport swallowed fluids and food from the pharynx to the stomach. The esophageal muscles governing bolus transport comprise circular striated muscle of the proximal esophagus and circular smooth muscle of the distal esophagus. Longitudinal smooth muscle contraction provides a mechanical advantage to bolus transit during circular smooth muscle contraction. Esophageal striated muscle is directly controlled by neural circuits originating in the central nervous system, resulting in coordinated contractions. In contrast, the esophageal smooth muscle is controlled by enteric circuits modulated by extrinsic central neural connections resulting in neural relaxation and contraction. The esophageal muscles are modulated by sensory information arising from within the lumen. Contraction or relaxation, which changes the diameter of the lumen, alters the intraluminal pressure and ultimately inhibits or promotes flow of content. This relationship that exists between the changes in diameter and concurrent changes in intraluminal pressure has been used previously to identify the "mechanical states" of the circular muscle; that is when the muscles are passively or actively, relaxing or contracting. Detecting these changes in the mechanical state of the muscle has been difficult and as the current interpretation of esophageal motility is based largely upon pressure measurement (manometry), subtle changes in the muscle function during peristalsis can be missed. We hypothesized that quantification of mechanical states of the esophageal circular muscles and the pressure-diameter properties that define them, would allow objective characterization of the mechanisms that govern esophageal peristalsis. To achieve this we analyzed barium swallows captured by simultaneous videofluoroscopy and pressure with impedance recording. From these data we demonstrated that intraluminal impedance measurements could be used to determine changes in the internal diameter of the lumen comparable with measurements from videofluoroscopy. Our data indicated that identification of mechanical state of esophageal muscle was simple to apply and revealed patterns consistent with the known neural inputs activating the different muscles during swallowing.
authors.affiliation: Department of Human Physiology, School of Medicine, Flinders University Bedford Park, SA, Australia.
authors.forename: Richard E
authors.initials: RE
authors.lastname: Leibbrandt
authors.affiliation: Department of Human Physiology, School of Medicine, Flinders UniversityBedford Park, SA, Australia; Department of Gastroenterology and Hepatology, School of Medicine, Flinders UniversityBedford Park, SA, Australia; Department of Surgery, School of Medicine, Flinders UniversityBedford Park, SA, Australia.
authors.forename: Phil G
authors.initials: PG
authors.lastname: Dinning
authors.affiliation: Department of Human Physiology, School of Medicine, Flinders University Bedford Park, SA, Australia.
authors.forename: Marcello
authors.initials: M
authors.lastname: Costa
authors.affiliation: Department of Gastroenterology and Hepatology, School of Medicine, Flinders University Bedford Park, SA, Australia.
authors.forename: Charles
authors.initials: C
authors.lastname: Cock
authors.affiliation: Department of Human Physiology, School of Medicine, Flinders University Bedford Park, SA, Australia.
authors.forename: Lukasz
authors.initials: L
authors.lastname: Wiklendt
authors.affiliation: Department of Human Physiology, School of Medicine, Flinders University Bedford Park, SA, Australia.
authors.forename: Guangsong
authors.initials: G
authors.lastname: Wang
authors.affiliation: Gastroenterology, Neurogastroenterology and Motility, University Hospitals LeuvenLeuven, Belgium; Translational Research Center for Gastrointestinal Diseases (TARGID), University of LeuvenLeuven, Belgium.
authors.forename: Jan
authors.initials: J
authors.lastname: Tack
authors.affiliation: Department of Radiology, University Hospitals Leuven Leuven, Belgium.
authors.forename: Dirk
authors.initials: D
authors.lastname: van Beckevoort
authors.affiliation: Gastroenterology, Neurogastroenterology and Motility, University Hospitals LeuvenLeuven, Belgium; Translational Research Center for Gastrointestinal Diseases (TARGID), University of LeuvenLeuven, Belgium; Neurosciences, ExpORL, University of LeuvenLeuven, Belgium.
authors.forename: Nathalie
authors.initials: N
authors.lastname: Rommel
authors.affiliation: Department of Human Physiology, School of Medicine, Flinders UniversityBedford Park, SA, Australia; Department of Gastroenterology and Hepatology, School of Medicine, Flinders UniversityBedford Park, SA, Australia.
authors.forename: Taher I
authors.initials: TI
authors.lastname: Omari
keywords: dysphagia; esophageal peristalsis; impedance; neural pathways; pressure; swallow