Esophageal peristalsis consists of initial inhibition (relaxation) followed by excitation (contraction), both of which move sequentially in the aboral direction. Initial inhibition results in receptive relaxation and bolus-induced luminal distension, which allows propulsion by the contraction with minimal resistance to flow. Similar to the contraction wave, luminal distension has unique waveform characteristics in normal subjects; both are modulated by bolus volume, bolus viscosity, and posture, suggesting a possible cause-and-effect relationship between the two. Distension contraction plots in patients with dysphagia with normal bolus clearance [high-amplitude esophageal contractions (HAECs), esophagogastric junction outflow obstruction (EGJOO), and functional dysphagia (FD)] reveal two major findings: 1) unlike normal subjects, there is luminal occlusion distal to bolus during peristalsis in certain patients, i.e., with type 3 achalasia and nonobstructive dysphagia; and 2) bolus travels through a narrow lumen esophagus during peristalsis in patients with HAECs, EGJOO, and FD. Aforementioned findings indicate a relative dynamic obstruction to the bolus flow during peristalsis and reduced distensibility of esophageal wall in the bolus segment of the esophagus. We speculate that a normal or supernormal contraction wave pushing bolus against resistance is the mechanism of dysphagia sensation in significant number of patients. Representations of distension and contraction, combined with objective measures of flow timing and distensibility are complementary to the current scheme of classifying esophageal motility disorders based solely on the characteristics of contraction phase of peristalsis. Better understanding of the distensibility of the bolus-containing segment of the esophagus during peristalsis will lead to the development of novel medical and surgical therapies in the treatment of dysphagia in significant number of patients.

Background: Reason for dysphagia in a significant number of patients remains unclear even after a thorough workup. Each swallow induces esophageal distension followed by contraction of the esophagus, both of which move sequentially along the esophagus. Manometry technique and current system of classifying esophageal motility disorders (Chicago Classification) is based on the analysis of the contraction phase of peristalsis. Goal: Whether patients with unexplained dysphagia have abnormalities in the distension phase of esophageal peristalsis is not known. Methods: Using Multiple Intraluminal esophageal impedance recordings, which allow determination of the luminal cross-sectional area during peristalsis, we studied patients with nutcracker esophagus (NC), esophagogastric junction outflow obstruction (EGJOO), and functional dysphagia (FD). Results: Distension contraction plots revealed that swallowed bolus travels significantly faster through the esophagus in all patient groups as compared to normals. The luminal cross-sectional area (amplitude of distension), and the area under the curve of distension were significantly smaller in patients with NC, EGJOO, and FD as compared to normals. Bolus traverses the esophagus in the shape of an “American Football” in normal subjects. On the other hand, in patients the bolus flow was fragmented. ROC curves revealed that bolus flow abnormalities during peristalsis are a sensitive and specific marker of dysphagia. Conclusion: Our findings reveal abnormality in the distension phase of peristalsis (a narrow lumen esophagus) in patients with dysphagia. We propose that the esophageal contraction forcing the swallowed bolus through a narrow lumen esophagus is the cause of dysphagia sensation in patients with normal contraction phase of peristalsis.

Background: Recent studies that utilized distension/contraction plots to study peristalsis reveal poor distension of the esophagus in patients with functional dysphagia and high amplitude contractions (HAEC) even though the contraction phase of peristalsis is normal in these patients. Aim: Determine biomechanical properties of the esophageal wall and bolus flow characteristics in patients with functional dysphagia and HAEC during primary peristalsis. Methods: Studies were performed in 30 healthy subjects, 30 patients with functional dysphagia and 25 patients with HAEC. Subjects swallowed 10ml, 0.5 N saline bolus, in the Trendelenburg position to study primary peristalsis. A custom-built software (Dplots) determined peak distension from the impedance measurements, pressure at peak distension, wall tension (Pressure x Radius), wall distensibility (CSA /pressure) and bolus flow (centimeter³/sec) in 4 segments of esophagus (between upper and lower esophageal sphincter). Results: Luminal CSA of distal esophagus was smaller and average bolus flow rate faster in patients with functional dysphagia and HAEC. Esophageal wall distensibility, a measure of esophageal wall compliance was lower and wall tension higher in the distal esophagus of both patient groups compared to normal subjects. Ultrasound imaging confirmed poor distension of the esophagus. A trend towards greater wall thickness at the peak of distension was found in functional dysphagia patients compared to normal subjects. Conclusions: A stiffer or non-compliant esophageal wall is the reason for poor distension of the esophagus during primary peristalsis in patients with functional dysphagia and HAEC.

(1) Background: Dysphagia affects around 16% of the US population. Diagnostic tests like X-ray barium swallow and endoscopy are used initially to diagnose the cause of dysphagia, followed by high-resolution esophageal manometry (HRM). If the above tests are normal, the patient is classified as functional dysphagia (FD), suggesting esophageal sensory dysfunction. HRM records only the contraction phase of peristalsis, not the distension phase. We investigated the utilization of esophageal distension–contraction patterns for the automatic classification of FD, using artificial intelligent shallow learners. (2) Methods: Studies were performed in 30 healthy subjects and 30 patients with FD. Custom-built software (Dplots 1.0) was used to extract relevant esophageal distension–contraction features. Next, we used multiple shallow learners, namely support vector machines, random forest, K-nearest neighbors, and logistic regression, to determine which had the best performance in terms of accuracy, precision, and recall. (3) Results: In the proximal segment, LR produced the best results, with accuracy of 91.7% and precision of 92.86%, using only distension features. In the distal segment, random forest produced accuracy of 90.5% and precision of 91.1% using both pressure and distension features. (4) Conclusions: Findings emphasize the crucial role of abnormality in the distension phase of peristalsis in FD patients.

Our findings underscore the superiority of distension features over contraction metrics in diagnosing esophageal dysfunctions. By leveraging state-of-the-art machine learning techniques, our study highlights the diagnostic potential of distension-contraction plots of peristalsis. Implementation of these plots could significantly enhance the accuracy of identifying patients with esophageal motor disorders, advocating for their adoption as the standard in clinical practice.

Swallow-related axial shortening of the esophagus is reduced, and there is no separation between the lower esophageal sphincter and crural diaphragm (CD) with swallowing in patients with achalasia esophagus. Fat in the hiatal opening of the esophagus appears to be replaced with fibrous tissue in patients with achalasia, resulting in tight anchoring between the LES and CD. The above findings explain low prevalence of hiatus hernia and the low compliance of the LES in achalasia esophagus.