Localizing the contractile deceleration point (CDP) in patients with abnormal esophageal pressure topography

Background The contractile deceleration point (CDP) is an important landmark for interpreting esophageal pressure topography (EPT) plots. Previous analysis in normal subjects confirmed that the CDP could be localized using an algorithm that found the time during peristalsis at which a maximal length of the distal esophagus was contracting concurrently (tML method). This study aimed to test the tML method for localizing CDP in patients with abnormal motility. Methods High‐resolution manometry studies of 75 patients with normal and disordered peristalsis were analyzed. Two experts, JEP and YX, used the original tangent‐intersection method to score CDP coordinates for the first two swallows of each study. Alternative computerized algorithms tested against the expert were: (i) the tML method, (ii & iii) the intercept between the leading edge of the 30‐mmHg isobaric contour and a line 2.0 cm (or 10% of esophageal length) proximal to the esophagogastric junction (EGJ) at rest, or (iv) the ‘tML‐3 cm’ method, which added the stipulation that the CDP be within 3 cm of the EGJ. Key Results All tested algorithms were highly correlated with the expert. However, the tMl‐3 cm method was better in the sense that it eliminated outliers (>1 s discrepancy with the expert) that occurred with the other methods usually attributable to weak distal peristalsis. Conclusions & Inferences Optimal automated CDP localization was achieved in both normal and a spectrum of abnormal motility using the tML method with the added stipulation that the CDP be restricted to within the distal 3 cm of the EGJ at rest.     

Automated calculation of the distal contractile integral in esophageal pressure topography with a region-growing algorithm

Background The distal contractile integral (DCI) is an index of contractile vigor in high‐resolution esophageal pressure topography (EPT) calculated as the product of amplitude, duration, and span of the distal esophageal contraction. The aim of this study was to develop an automated algorithm calculating DCI. Methods The DCI was calculated conventionally using ManoView? (Given Imaging, Los Angeles, CA, USA) software in EPT studies from 72 controls and 20 patients and compared to the calculation using a MATLAB? (Version 7.9.0, R2009b; The MathWorks Inc., Natick, MA, USA) ‘region‐growing’ algorithm. This algorithm first established the spatial limits of the distal contraction (the proximal pressure trough to either the distal pressure trough or to the superior margin of the lower esophageal sphincter at rest). Pixel‐by‐pixel horizontal line segments were then analyzed within this span starting at the pressure maximum and extending outward from that point. The limits of ‘region‐growing’ were defined either by the spatial DCI limits or by encountering a pressure <20 mmHg. The DCI was then calculated as the total units of mmHg s cm greater than 20 mmHg within this domain. Key Results Excellent correlation existed between the two methods (r = 0.98, P < 0.001). The DCI values obtained with the conventional calculation were slightly but significantly greater than with the region‐growing algorithm. Differences were attributed to the inclusion of vascular pressures in the conventional calculation or to differences in localization of the distal limit of the DCI. Conclusions & Inferences The proposed region‐growing algorithm provides an automated method to calculate DCI that limits inclusion of vascular pressure artifacts and minimizes the need for user input in data analysis.     

High‐resolution esophageal pressure topography is superior to conventional sleeve manometry for the detection of transient lower esophageal sphincter relaxations associated with a reflux event

Background Transient lower esophageal sphincter relaxations (TLESRs) are the main mechanism underlying gastro‐esophageal reflux and are detected during manometric studies using well defined criteria. Recently, high‐resolution esophageal pressure topography (HREPT) has been introduced and is now considered as the new standard to study esophageal and lower esophageal sphincter (LES) function. In this study we performed a head‐to‐head comparison between HREPT and conventional sleeve manometry for the detection of TLESRs. Methods A setup with two synchronized MMS‐solar systems was used. A solid state HREPT catheter, a water‐perfused sleeve catheter, and a multi intraluminal impedance pH (MII‐pH) catheter were introduced in 10 healthy volunteers (M6F4, age 19–56). Subjects were studied 0.5 h before and 3 h after ingestion of a standardized meal. Tracings were blinded and analyzed by the three authors according to the TLESR criteria. Key Results In the HREPT mode 156 TLESRs were scored, vs 143 during sleeve manometry (P = 0.10). Hundred and twenty‐three TLESRs were scored by both techniques. Of all TLESRs (177), 138 were associated with reflux (78%). High‐resolution esophageal pressure topography detected significantly more TLESRs associated with a reflux event (132 vs 119, P = 0.015) resulting in a sensitivity for detection of TLESRs with reflux of 96% compared to 86% respectively. Analysis of the discordant TLESRs associated with reflux showed that TLESRs were missed by sleeve manometry due to low basal LES pressure (N = 5), unstable pharyngeal signal (N = 4), and residual sleeve pressure >2 mmHg (N = 10). Conclusions & Inferences The HREPT is superior to sleeve manometry for the detection of TLESRs associated with reflux. However, rigid HREPT criteria are awaited.