Mechanical properties of the esophageal wall

A B S T R A C T Pressure-diameter curves of the esopha- gus were obtained to define its mechanical properties.The mucosal contribution to the strength of the esopha- gus was negligible until the outer diameter almost doubled, suggesting that small intraluminal pressures are held by the muscle layer alone.For larger deforma- tions mucosal contribution increased and at failure the mucosa held over one-half of the failure pressure of the esophagus.The paths followed during loading and unloading are different and exhibit hysteresis.They are influenced by the rate of pressure change, being more compliant for low rates of pressure change.They are influenced by the history of loading, being different for successive loading- unloading cycles.If enough loading-unloading cycles are repeated a stable loop is reached, which does not change thereafter.Both the mucosa and the whole esophagus show in- creasing stiffness with increasing pressure.This be- havior can be represented by a simple exponential re- lationship.However, at rapid rates of pressure increases, the esophageal muscles produce sigmoid loading curves, which gradually become exponential when repeating loading. INTRODUCTIONAn understanding of the mechanical characteristics of the materials constituting the walls of the gastrointestinal tract is necessary to evaluate its normal behavior as well as conditions of failure, to understand the mechanics of bolus transport, and to develop suitable biomaterials for replacement, when needed.Despite a renewed in- terest in biomechanics, as evidenced by recent studies on the mechanical properties of blood vessels (1-3), lungs (4), muscles (5, 6), tendons (7, 8), skin (9), and many other organs and tissues (10), little information is available on the mechanical properties of the gastro- Dr.