Intersubject and interswallow variability in topography of esophageal motility

Topographic plots linking averaged manometric data in time and space suggest that sequential contraction segments form esophageal peristalsis. A system capable of plotting individual swallows was developed to verify this observation and to determine intersubject and interswallow variability in their topographic appearance. Fourteen volunteers were studied with a novel computerized assimilation method capable of generating topographic contour plots as well as conventional wave forms for analysis. Contraction segments in the proximal body and lower sphincter were identified in all subjects as being separate from the remainder of the esophagus with little interswallow variation. The appearance of peristalsis through the distal body was more variable because of its intermittent separation into two dominant contraction segments (59.8% of swallows) that had poorly correlated contraction strength (median r = 0.15). Intersubject variability exceeded interswallow variability in topographic landmarks, resulting in distinctive topographic "fingerprints" of peristalsis for each subject. We conclude that topographic plotting of single swallows is feasible and confirms the presence of sequential contraction segments in the esophagus. Interswallow variability helps demonstrate two segments within the smooth-muscle body, an anatomical region of seeming homogeneity, that have sufficient contraction independence to indicate separate neuromuscular units responding to different contractile influences.