Figure 3 - Contour plot topographic analysis of esophageal motility in achalasia.

Topographic analysis is a method of axial data interpolation derived from computerized plotting of data from multiple, closely spaced, solid-state recording transducers. The interpolated pressure information is plotted as a two-dimensional contour plot in which pressure amplitude is coded by color. a: A normal esophageal study with propagation of the peristaltic wave and relaxation of the lower esophageal sphincter (LES). The upper esophageal sphincter is also depicted at the top of the panel, demonstrating a higher basal pressure and shorter relaxation phase. b: Study for a patient with achalasia demonstrating integrity of proximal esophageal peristalsis with mid and distal esophageal body aperistalsis (simultaneous contractions). Incomplete relaxation of the LES and elevated esophagastric pressure gradient are also demonstrated. c: A study from a patient with achalasia with complete esophageal aperistalsis and incomplete relaxation of the hypertensive LES. Although there is partial inhibition of the LES, the relaxation pressures exceed 40 mmHg. An esophagogastric pressure gradient is evident in the distal esophagus.