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

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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.