Impedance planimetry is an imaging technique that displays the distensibility of hollow viscera. Inside a bag filled with a conductive solution multiple impedance tracings between pairs of electrodes are converted to estimate cross sectional areas. With simultaneous measurement of intrabag pressure distensibility (smallest cross sectional area vs. intrabag pressure) is calculated. Impedance planimetry measurements characterize biomechanical properties of the esophago-gastric junction, the esophageal body and the pharyngo-esophageal sphincter. In healthy volunteers distensbiliity of the esophagogastric junction was lowest at the diaphragmatic hiatus and cross sectional areas of 38, 94, and 264 mm2 at distension volumes of 20, 30 and 40 ml were reported. Distension of the esophageal body resulted in a cylindrical bag configuration up to a plateau of 400 mm2 in most subjects. In patients with achalasia distensibility of the esophagogastric junction was reduced even when sphincter pressure was in the normal range. In patients with eosinophilic esophagitis distensibility was decreased at the esophagogastric junction and in the tubular esophagus. By contrast, in subjects with gastro-esophageal reflux disease the diameter of the esophagogastric junction was larger at any given intrabag pressure than in controls. In clinical practice impedance planimetry of the esophagus serves as a diagnostic test for the work-up of dysphagia, especially if structural or mucosal lesions are absent and peristalsis of the esophageal body is preserved. Impedance planimetry can be performed during or immediately after surgical or endoscopic procedures and is therefore a valuable tool for the ad hoc assessment of the effects of therapeutic interventions.
KeywordsLower Esophageal Sphincter Antireflux Surgery Lower Esophageal Sphincter Pressure Eosinophilic Esophagitis Mixed Connective Tissue Disease
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