Esophageal Transport Research Articles

Insights into metachronal propulsion's influence on Ellis fluid flow across tri‐layers amid dynamic thermal transport: Theoretical study

AbstractCilia‐based therapies are emerging for treating ciliopathies, such as inhalable drugs to propel mucus out of the lungs of patients with cystic fibrosis. This has motivated scientists and researchers to investigate cilia motion mechanics and viscoelastic fluid properties for biomedical engineering applications and disease treatments. In line with the diverse biological implications, this study focuses on the mass and heat transfer flow of tri‐layered non‐Newtonian fluids propelled by ciliary beating in a cylindrical tube. The fluid remains incompressible, with distinct layers that do not mix. The study considers the impact of mass and heat transfer in three distinct regimes, ensuring continuity at the interfaces. Mathematical modeling incorporating the lubrication approximation, small Reynolds number, and long wavelength approximation is employed for simplification. The resulting differential equations, along with boundary conditions, yield accurate solutions for temperature, velocity, and concentration fields in the three fluid layers and are discussed graphically. Key findings demonstrate that velocity and temperature fields are most pronounced in the inner fluid layer (PCL), while the concentration profile is most prominent in the outer layers (ACL), with moderate behavior in the central region. The implications of this research extend to diverse fields, including mucus clearance from the respiratory tract, microfluidics, esophageal transport, biofluid mechanics, and other areas of physiology. The insights gained from this study have promising applications in developing new treatments and biomedical engineering solutions.

Role of mechanoregulation in mast cell-mediated immune inflammation of the smooth muscle in the pathophysiology of esophageal motility disorders.

Major esophageal disorders involve obstructive transport of bolus to the stomach, causing symptoms of dysphagia and impaired clearing of the refluxed gastric contents. These may occur due to mechanical constriction of the esophageal lumen or loss of relaxation associated with deglutitive inhibition, as in achalasia-like disorders. Recently, immune inflammation has been identified as an important cause of esophageal strictures and the loss of inhibitory neurotransmission. These disorders are also associated with smooth muscle hypertrophy and hypercontractility, whose cause is unknown. This review investigated immune inflammation in the causation of smooth muscle changes in obstructive esophageal bolus transport. Findings suggest that smooth muscle hypertrophy occurs above the obstruction and is due to mechanical stress on the smooth muscles. The mechanostressed smooth muscles release cytokines and other molecules that may recruit and microlocalize mast cells to smooth muscle bundles, so that their products may have a close bidirectional effect on each other. Acting in a paracrine fashion, the inflammatory cytokines induce genetic and epigenetic changes in the smooth muscles, leading to smooth muscle hypercontractility, hypertrophy, and impaired relaxation. These changes may worsen difficulty in the esophageal transport. Immune processes differ in the first phase of obstructive bolus transport, and the second phase of muscle hypertrophy and hypercontractility. Moreover, changes in the type of mechanical stress may change immune response and effect on smooth muscles. Understanding immune signaling in causes of obstructive bolus transport, type of mechanical stress, and associated smooth muscle changes may help pathophysiology-based prevention and targeted treatment of esophageal motility disorders.NEW & NOTEWORTHY Esophageal disorders such as esophageal stricture or achalasia, and diffuse esophageal spasm are associated with smooth muscle hypertrophy and hypercontractility, above the obstruction, yet the cause of such changes is unknown. This review suggests that smooth muscle obstructive disorders may cause mechanical stress on smooth muscle, which then secretes chemicals that recruit, microlocalize, and activate mast cells to initiate immune inflammation, producing functional and structural changes in smooth muscles. Understanding the immune signaling in these changes may help pathophysiology-based prevention and targeted treatment of esophageal motility disorders.

Concentration and Thermal Analysis of immiscible Tangent hyperbolic fluid with distinct viscosity through horizontal asymmetric channel: Theoretical and Observational study

This study examines cilia induced Tangent hyperbolic fluid flow with distinct viscosity, density in addition to thermal conductivity through horizontal asymmetric channel in two adjacent layers. The impact of mass and heat transfer in two adjacent layers with continuity at the interface is considered. The governing equations for double-layer fluid flow was modelled and simplified via well-known approximation long wavelength and small Reynolds number. The subsequent equations with boundary conditions provide exact solution for the velocity profile, temperature field and concentration distribution in both layers. The outcomes of occurring parameters on temperature, velocity and concentration field are explained graphically. The major findings show that velocity field and temperature field are extreme in internal fluid layer and concentration distribution is highest at external fluid layers. In both the layers by rising viscosities, thermal conductivities, fluid parameters and temperature profile increases. Potential applications for the current work include mucus clearance from respiratory tract, microfluidics, oesophageal transport, bio fluid mechanism and other fields of physiology.

Radionuclide Diagnosis of Esophageal Dysmotility and Gastroesophageal Reflux in Patients with Systemic Sclerosis

Objective: to evaluate the possibilities of dynamic scintigraphy for the diagnosis of esophageal dysmotility (ED) and gastroesophageal reflux (GER) in patients with systemic sclerosis (SS).Material and methods. The study group included 77 patients with established SS of different disease duration (from several months to 30 years) who underwent Technephyt 99mTc dynamic esophageal scintigraphy using two-stage protocol. During the first stage, the esophageal transport function was evaluated; during the second stage, the presence and severity of GER were assessed. Scans were analyzed using visual assessment, quantitative estimation of time/activity curves, and a proposed three-point scale for evaluating ED and GER severity. The control group consisted of 19 practically healthy individuals who underwent a routine examination to exclude digestive system and gastrointestinal tract diseases, the algorithm of which included dynamic scintigraphy.Results. ED was found in 74 of 77 patients (96%). According to three-point scale, severe ED (3 points) was registrated in 41 (55%) patients, moderate ED (2 points) in 15 (21%), and mild ED in 18 (24%). GER was diagnosed in 35 of 77 cases (45%): mild GER in 13 (37%), moderate GER (2 points) in 22 (63%), and none of the patients was found to have severe GER (3 points). A significant relationship between the presence of GER and the severity of ED was not obtained, but a direct correlation was established between ED and GER severity.Conclusion. Most SS patients demonstrated ED of varying severity associated with mild and moderate GER in nearly 45% of the cases. The study results confirm the practical significance of dynamic scintigraphy for assessing the esophageal transport function and GER in SS patients.

Peristaltic regimes in esophageal transport.

A FLIP device gives cross-sectional area along the length of the esophagus and one pressure measurement, both as a function of time. Deducing mechanical properties of the esophagus including wall material properties, contraction strength, and wall relaxation from these data are a challenging inverse problem. Knowing mechanical properties can change how clinical decisions are made because of its potential for in-vivo mechanistic insights. To obtain such information, we conducted a parametric study to identify peristaltic regimes by using a 1D model of peristaltic flow through an elastic tube closed on both ends and also applied it to interpret clinical data. The results gave insightful information about the effect of tube stiffness, fluid/bolus density and contraction strength on the resulting esophagus shape through quantitive representations of the peristaltic regimes. Our analysis also revealed the mechanics of the opening of the contraction area as a function of bolus flow resistance. Lastly, we concluded that peristaltic driven flow displays three modes of peristaltic geometries, but all physiologically relevant flows fall into two peristaltic regimes characterized by a tight contraction.

Mechanics informed fluoroscopy of esophageal transport.

Fluoroscopy is a radiographic procedure for evaluating esophageal disorders such as achalasia, dysphasia and gastroesophageal reflux disease. It performs dynamic imaging of the swallowing process and provides anatomical detail and a qualitative idea of how well swallowed fluid is transported through the esophagus. In this work, we present a method called mechanics informed fluoroscopy (FluoroMech) that derives patient-specific quantitative information about esophageal function. FluoroMech uses a convolutional neural network to perform segmentation of image sequences generated from the fluoroscopy, and the segmented images become input to a one-dimensional model that predicts the flow rate and pressure distribution in fluid transported through the esophagus. We have extended this model to identify and estimate potential physiomarkers such as esophageal wall stiffness and active relaxation ahead of the peristaltic wave in the esophageal musculature. FluoroMech requires minimal computational time and hence can potentially be applied clinically in the diagnosis of esophageal disorders.

Stabilization approaches for the hyperelastic immersed boundary method for problems of large-deformation incompressible elasticity

The immersed boundary method is a mathematical framework for modeling fluid–structure interaction. This formulation describes the momentum, viscosity, and incompressibility of the fluid–structure system in Eulerian form, and it uses Lagrangian coordinates to describe the structural deformations, stresses, and resultant forces. Integral transforms with Dirac delta function kernels connect the Eulerian and Lagrangian frames. The fluid and the structure are both typically treated as incompressible materials. The discretization scheme can readily enforce incompressibility exactly for the Eulerian velocity field. Because of the regularization of the Dirac delta function kernel, however, the Lagrangian velocity field of the solid generally does not retain this property. To obtain an immersed method for incompressible hyperelastic structures that is robust under large structural deformations, we introduce a volumetric energy in the solid region that stabilizes the formulation and improves the accuracy of the numerical scheme. This formulation augments the discrete Eulerian Lagrange multiplier for the incompressibility constraint, thereby improving the original method’s accuracy. This volumetric energy is incorporated by decomposing the strain energy into isochoric and dilatational components, as in standard solid mechanics formulations of nearly incompressible elasticity. We study the performance of the stabilized method using several quasi-static solid mechanics benchmarks, a dynamic fluid–structure interaction benchmark, and a detailed three-dimensional model of esophageal transport. The accuracy achieved by the stabilized immersed formulation is empirically demonstrated to be comparable to that of a stabilized finite element method for incompressible elasticity using similar numbers of structural degrees of freedom.

Study Biophysics of Esophageal Transport by Combining Simulation, Modeling and Bio-Mechanical Analysis Based on In-Vivo Data

The human esophagus is a tubular organ that transfers food bolus to stomach, through complicated interactions among neural-controlled muscle activation (including upper striated muscle and lower smooth muscle), passive elasticity of esophageal wall and liquid-like bolus. The muscle physiology, including sequential contraction of esophageal body and tonic contraction of lower esophageal sphincter (LES), underpins various aspects of esophageal physiology and pathophysiology. With a team effort across physicians and engineers, several fully-coupled simulation models were developed to study muscle synchrony/asynchrony, myo-architecture, tissue stiffening at organ level, and will be briefly reviewed. More recently, with in-vivo clinical data such as High-resolution impedance manometry (HRIM), a hybrid diagnostic framework was developed. This framework first constructed quantitative geometry from measured impedance based on biophysical analysis, and then fed this geometric information into a simulation model of bolus transit. The predicted velocity elucidates the flow rate in normal and abnormal cases to differentiate motility functionality, whereas the predicted pressure informs stress and stiffness of the tissue. With another in-vivo test, Functional lumen imaging probe (FLIP), the muscle stiffness of esophageal body is analyzed and compared with in-vitro data. The LES property during volumetric dilation, including its phasic contraction-relaxation period and pattern is illustrated and compared among different groups.

An XROMM Study of Food Transport and Swallowing in Channel Catfish.

SynopsisMost predatory ray-finned fishes swallow their food whole, which can pose a significant challenge, given that prey items can be half as large as the predators themselves. How do fish transport captured food from the mouth to the stomach? Prior work indicates that, in general, fish use the pharyngeal jaws to manipulate food into the esophagus, where peristalsis is thought to take over. We used X-Ray Reconstruction of Moving Morphology to track prey transport in channel catfish (Ictalurus punctatus). By reconstructing the 3D motions of both the food and the catfish, we were able to track how the catfish move food through the head and into the stomach. Food enters the oral cavity at high velocities as a continuation of suction and stops in the approximate location of the branchial basket before moving in a much slower, more complex path toward the esophagus. This slow phase coincides with little motion in the head and no substantial mouth opening or hyoid depression. Once the prey is in the esophagus, however, its transport is surprisingly tightly correlated with gulping motions (hyoid depression, girdle retraction, hypaxial shortening, and mouth opening) of the head. Although the transport mechanism itself remains unknown, to our knowledge, this is the first description of synchrony between cranial expansion and esophageal transport in a fish. Our results provide direct evidence of prey transport within the esophagus and suggest that peristalsis may not be the sole mechanism of esophageal transport in catfish.

Hiatal hernias in patients with GERD-like symptoms: evaluation of dynamic real-time MRI vs endoscopy.

To assess the diagnostic potential of real-time MRI for assessment of hiatal hernias in patients with GERD-like symptoms compared to endoscopy. One hundred eight patients with GERD-like symptoms were included in this observational cohort study between 2015 and 2017. Real-time MRI was performed at 3.0 Tesla with temporal resolution of 40ms, dynamically visualizing the esophageal transport of a pineapple juice bolus, its passage through the gastroesophageal junction, and functional responses during Valsalva maneuver. Hernia detection on MRI and endoscopy was calculated using contingency tables with diagnosis of hernia on either modality as reference. Of 108 patients, 107 underwent successful MRI without adverse events; 1 examination was aborted to inability to swallow pineapple juice in supine position. No perforation or acute bleeding occurred during endoscopy. Median examination time was 15min. Eighty-five patients (79.4%) were diagnosed with hiatal hernia on either real-time MRI or endoscopy. Forty-six hernias were visible on both modalities. Seventeen hernias were evident exclusively on MRI, and 22 exclusively on endoscopy. Sixteen of the 63 MRI-detected hernias (25.4%) were detectable only during Valsalva maneuver, which were smaller compared to hernias at rest (median - 13.5 vs - 33.0mm, p < 0.001). Diagnostic accuracy for hernia detection was comparable for MRI and endoscopy (sensitivity 74% vs 80%, p = 0.4223; specificity 100% vs 100%, p > 0.99). Real-time MRI is a fast and safe modality for assessment of the gastroesophageal junction, without radiation exposure or administration of gadolinium-based contrast media. Although MRI and endoscopy yield comparable diagnostic accuracy, dynamic MRI sequences are able to visualize hiatal hernias that were occult on static MRI sequences or endoscopy in a relevant number of cases. • Real-time MRI is a safe and fast imaging modality for examination of the gastroesophageal junction, combining anatomical and functional information for enhanced detection of hiatal hernias. • Real-time MRI and endoscopy yield comparably high diagnostic accuracy: real-time MRI visualizes hiatal hernias that were occult on endoscopy in a relevant number of patients; however, several hiatal hernias detected on endoscopy were occult on real-time MRI. • There is clinical potential of real-time MR imaging in patients with GERD-like symptoms and equivocal findings on endoscopy or pH-metry, for anatomical visualization in patients planned for surgical intervention, or those with suspected fundoplication failures.

Intra- and interobserver variability in the diagnosis of GERD by real-time MRI

The purpose of this study was to assess the reproducibility of functional and anatomical parameters of swallowing events as determined by real-time MRI at 40 ms temporal resolution (25 frames per second). Twenty-three consecutive patients with gastroesophageal reflux disease (GERD) underwent real-time MRI of the gastroesophageal junction at 3.0 T. Real-time MRI was based on highly undersampled radial fast low angle shot (FLASH) acquisitions with iterative image reconstruction by regularized nonlinear inversion (NLINV). MRI movies visualized the esophageal transport of a pineapple juice bolus, its passage through the gastroesophageal junction and functional responses during a Valsalva maneuver. His-angle, sphincter position, sphincter length and sphincter transit time were assessed by two radiologists. Interobserver and intraobserver intraclass correlation coefficients (ICC) were evaluated and Bland-Altman plots were constructed to assess the observer agreement. Interobserver agreement was excellent for sphincter transit time (ICC = 0.92), His-angle (ICC = 0.93), His-angle during Valsalva maneuver (ICC = 0.91) and sphincter-to-diaphragm distance (ICC = 0.98). Sphincter length and oesophageal diameter showed good interobserver agreement (ICC = 0.62 and ICC = 0.70). Intraobserver agreement was good for sphincter length (ICC = 0.80) and excellent for sphincter transit time, His-angle and His-angle during Valsalva maneuver, sphincter-to-diaphragm distance, and esophageal diameter (ICC = 0.91; ICC = 0.97; ICC = 0.97; ICC = 0.998; ICC = 0.93). All functional parameters of the gastroesophageal junction had good to excellent reproducibility. Visual assessment of Bland Altman plots did not reveal any systematic interobserver bias. In conclusion, the visualization of swallowing events by real-time MRI has a high potential for clinical application in gastroesophageal reflux disease.

A continuum mechanics-based musculo-mechanical model for esophageal transport

In this work, we extend our previous esophageal transport model using an immersed boundary (IB) method with discrete fiber-based structural model, to one using a continuum mechanics-based model that is approximated based on finite elements (IB-FE). To deal with the leakage of flow when the Lagrangian mesh becomes coarser than the fluid mesh, we employ adaptive interaction quadrature points to deal with Lagrangian–Eulerian interaction equations based on a previous work (Griffith and Luo [1]). In particular, we introduce a new anisotropic adaptive interaction quadrature rule. The new rule permits us to vary the interaction quadrature points not only at each time-step and element but also at different orientations per element. This helps to avoid the leakage issue without sacrificing the computational efficiency and accuracy in dealing with the interaction equations. For the material model, we extend our previous fiber-based model to a continuum-based model. We present formulations for general fiber-reinforced material models in the IB-FE framework. The new material model can handle non-linear elasticity and fiber-matrix interactions, and thus permits us to consider more realistic material behavior of biological tissues. To validate our method, we first study a case in which a three-dimensional short tube is dilated. Results on the pressure-displacement relationship and the stress distribution matches very well with those obtained from the implicit FE method. We remark that in our IB-FE case, the three-dimensional tube undergoes a very large deformation and the Lagrangian mesh-size becomes about 6 times of Eulerian mesh-size in the circumferential orientation. To validate the performance of the method in handling fiber-matrix material models, we perform a second study on dilating a long fiber-reinforced tube. Errors are small when we compare numerical solutions with analytical solutions. The technique is then applied to the problem of esophageal transport. We use two fiber-reinforced models for the esophageal tissue: a bi-linear model and an exponential model. We present three cases on esophageal transport that differ in the material model and the muscle fiber architecture. The overall transport features are consistent with those observed from the previous model. We remark that the continuum-based model can handle more realistic and complicated material behavior. This is demonstrated in our third case where a spatially varying fiber architecture is included based on experimental study. We find that this unique muscle fiber architecture could generate a so-called pressure transition zone, which is a luminal pressure pattern that is of clinical interest. This suggests an important role of muscle fiber architecture in esophageal transport.

FORMULATION AND EVALUATION OF ASPIRIN RELEASE FROM MATRIX PELLETS COMPRESSED INTO MUPS TABLET

MUPS (Multiple Unit Pellets System):&#x0D; The oral route of drug administration is the most important and most user-friendly route of administration. In recent years, Multiple Unit Pellet Systems (MUPS) tablets are widely used in solid dosage form design. MUPS is considered to provide pharmacokinetic advantages compared to monolithic dosage forms. Typically, modified release pellets are contained in MUPS tablets. Modified release drug delivery systems have acquired very important role in pharmaceutical research and development.1&#x0D; 1.1Advantages of Compaction of MUPS over Conventional Modified-Release Tablets and/or Pellet-Filled Capsules and Tablets. &#x0D; &#x0D; The compression of multiparticulates into tablets, unlike the hard gelatin capsule, is a tamper-proof dosage form and has greater physicochemical and microbiological stability of pellets as they are embedment in the inert matrix.&#x0D; Tablets have less difficulty in esophageal transport than capsules.&#x0D; Tablets containing coated subunits can be prepared at a lower cost than these subunits filled into hard gelatin capsules because of higher production rate of the tablet press.&#x0D; The expensive control of capsule integrity after filling is also eliminated.&#x0D; In addition, tablets containing multiparticulates without losing the controlled-release properties could be scored, which allow a more flexible dosage regimen.&#x0D;

Could the peristaltic transition zone be caused by non-uniform esophageal muscle fiber architecture? A simulation study.

Based on a fully coupled computational model of esophageal transport, we analyzed how varied esophageal muscle fiber architecture and/or dual contraction waves (CWs) affect bolus transport. Specifically, we studied the luminal pressure profile in those cases to better understand possible origins of the peristaltic transition zone. Two groups of studies were conducted using a computational model. The first studied esophageal transport with circumferential-longitudinal fiber architecture, helical fiber architecture and various combinations of the two. In the second group, cases with dual CWs and varied muscle fiber architecture were simulated. Overall transport characteristics were examined and the space-time profiles of luminal pressure were plotted and compared. Helical muscle fiber architecture featured reduced circumferential wall stress, greater esophageal distensibility, and greater axial shortening. Non-uniform fiber architecture featured a peristaltic pressure trough between two high-pressure segments. The distal pressure segment showed greater amplitude than the proximal segment, consistent with experimental data. Dual CWs also featured a pressure trough between two high-pressure segments. However, the minimum pressure in the region of overlap was much lower, and the amplitudes of the two high-pressure segments were similar. The efficacy of esophageal transport is greatly affected by muscle fiber architecture. The peristaltic transition zone may be attributable to non-uniform architecture of muscle fibers along the length of the esophagus and/or dual CWs. The difference in amplitude between the proximal and distal pressure segments may be attributable to non-uniform muscle fiber architecture.

Simulation studies of the role of esophageal mucosa in bolus transport.

Based on a fully coupled computational model for esophageal transport, we analyzed the role of the mucosa (including the submucosa) in esophageal bolus transport and how bolus transport is affected by mucosal stiffness. Two groups of studies were conducted using a computational model. In the first group, a base case that represents normal esophageal transport and two hypothetical cases were simulated: (1) esophageal mucosa replaced by muscle and (2) esophagus without mucosa. For the base case, the geometric configuration of the esophageal wall was examined and the mechanical role of mucosa was analyzed. For the hypothetical cases, the pressure field and transport features were examined. In the second group of studies, cases with mucosa of varying stiffness were simulated. Overall transport characteristics were examined, and both pressure and geometry were analyzed. Results show that a compliant mucosa helped accommodate the incoming bolus and lubricate the moving bolus. Bolus transport was marginally achieved without mucosa or with mucosa replaced by muscle. A stiff mucosa greatly impaired bolus transport due to the lowered esophageal distensibility and increased luminal pressure. We conclude that mucosa is essential for normal esophageal transport function. Mechanically stiffened mucosa reduces the distensibility of the esophagus by obstructing luminal opening and bolus transport. Mucosal stiffening may be relevant in diseases characterized by reduced esophageal distensibility, elevated intrabolus pressure, and/or hypertensive muscle contraction such as eosinophilic esophagitis and jackhammer esophagus.

A continuum mechanics-based musculo-mechanical model for esophageal transport

A continuum mechanics-based musculo-mechanical model for esophageal transport

Simulation studies of circular muscle contraction, longitudinal muscle shortening, and their coordination in esophageal transport.

On the basis of a fully coupled active musculomechanical model for esophageal transport, we aimed to find the roles of circular muscle (CM) contraction and longitudinal muscle (LM) shortening in esophageal transport, and the influence of their coordination. Two groups of studies were conducted using a computational model. In the first group, bolus transport with only CM contraction, only LM shortening, or both was simulated. Overall features and detailed information on pressure and the cross-sectional area (CSA) of mucosal and the two muscle layers were analyzed. In the second group, bolus transport with varying delay in CM contraction or LM shortening was simulated. The effect of delay on esophageal transport was studied. For cases showing abnormal transport, pressure and CSA were further analyzed. CM contraction by itself was sufficient to transport bolus, but LM shortening by itself was not. CM contraction decreased the CSA and the radius of the muscle layer locally, but LM shortening increased the CSA. Synchronized CM contraction and LM shortening led to overlapping of muscle CSA and pressure peaks. Advancing LM shortening adversely influenced bolus transport, whereas lagging LM shortening was irrelevant to bolus transport. In conclusion, CM contraction generates high squeezing pressure, which plays a primary role in esophageal transport. LM shortening increases muscle CSA, which helps to strengthen CM contraction. Advancing LM shortening decreases esophageal distensibility in the bolus region. Lagging LM shortening no longer helps esophageal transport. Synchronized CM contraction and LM shortening seems to be most effective for esophageal transport.

A fully resolved active musculo-mechanical model for esophageal transport

Esophageal transport is a physiological process that mechanically transports an ingested food bolus from the pharynx to the stomach via the esophagus, a multi-layered muscular tube. This process involves interactions between the bolus, the esophagus, and the neurally coordinated activation of the esophageal muscles. In this work, we use an immersed boundary (IB) approach to simulate peristaltic transport in the esophagus. The bolus is treated as a viscous fluid that is actively transported by the muscular esophagus, and the esophagus is modeled as an actively contracting, fiber-reinforced tube. Before considering the full model of the esophagus, however, we first consider a standard benchmark problem of flow past a cylinder. Next a simplified version of our model is verified by comparison to an analytic solution to the tube dilation problem. Finally, three different complex models of the multi-layered esophagus, which differ in their activation patterns and the layouts of the mucosal layers, are extensively tested. To our knowledge, these simulations are the first of their kind to incorporate the bolus, the multi-layered esophagus tube, and muscle activation into an integrated model. Consistent with experimental observations, our simulations capture the pressure peak generated by the muscle activation pulse that travels along the bolus tail. These fully resolved simulations provide new insights into roles of the mucosal layers during bolus transport. In addition, the information on pressure and the kinematics of the esophageal wall resulting from the coordination of muscle activation is provided, which may help relate clinical data from manometry and ultrasound images to the underlying esophageal motor function.

A fully resolved active musculo-mechanical model for esophageal transport

A fully resolved active musculo-mechanical model for esophageal transport

Diagnostische Vorgehensweise bei Pferden mit Dysphagie

The term dysphagia, defined as the inability to swallow, is commonly used to describe problems with eating. Eating and especially swallowing is a complex process and morphological as well as functional problems can lead to disturbances. Prehension, mastication, swallowing itself and oesophageal transport can be affected. This article intends not to summarise differential diagnoses but to describe how to work up a case presented with dysphagia.