Mechanical properties of the esophageal wall.

Pressure-diameter curves of the esophagus were obtained to define its mechanical properties. The mucosal contribution to the strength of the esophagus was negligible until the outer diameter almost doubled, suggesting that small intraluminal pressures are held by the muscle layer alone. For larger deformations 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 increasing stiffness with increasing pressure. This behavior can be represented by a simple exponential relationship. However, at rapid rates of pressure increases, the esophageal muscles produce sigmoid loading curves, which gradually become exponential when repeating loading.