Mechanical Instability of Aorta due to Intraluminal Pressure

Dynamic mechanical instability in aorta due to intraluminal pressure may result in a buckling-type deformation and an increase in the pressure-induced tissue stresses and strains. The stability behavior of thoracic aorta was investigated with two boundary conditions that represented two extreme cases of in vivo constraints. The pinned-pinned boundary condition (PPBC) resulted in a decoupled system of equations while the equations for the clamped-clamped boundary condition (CCBC) were coupled. The stability regions around a physiological reference point were generated and the effects of variations in loading and geometric parameters were studied. In CCBC, the critical intraluminal pressures were higher by a factor of two to four compared to PPBC. The highest critical pressures remained below the peak aortic pressures that occur in motor vehicle accidents, which confirmed that mechanical instability can be a mechanism contributing to traumatic injury and rupture of aorta.