Localization of the contractile deceleration point (CDP) and measurement of distal latency (DL) on an esophageal pressure topography plot

Physiologically, the CDP is the landmark in the distal esophagus where bolus transport transitions from peristalsis to the globular phrenic ampulla (note the conformation of the ampulla distal to the CDP in the fluoroscopy inset). On the pressure topography plot, the CDP is localized by the intersection of tangents drawn to the 30 mmHg isobaric contour (black line) for the early and late phases of the contraction. Note that for the early phase of the contraction (peristalsis), the slope of the tangent is the CFV, indicative of the propagation velocity of peristalsis. The DL, a measure of whether or not the distal esophageal contraction is timely or premature, is measured as the interval between UES relaxation and the CDP, with 4.5 seconds being the lower limit of normal.