Elasticity Change along the Aorta is a Mechanism for Supporting the Physiological Self-organization of Tornado-like Blood Flow

We performed an experimental study of the elastic properties of the aorta by several independent methods, including the elastometry of the porcine aorta in different stretching modes, aortography in an acute porcine experiment with various levels of blood pressure, and contrast multislice computed tomography (MSCT) of the aorta in a healthy volunteer. In previous studies, it was shown that the swirling nature of the blood flow in the heart chambers and the aorta may be described in terms of the hydrodynamic model of tornado-like self-organizing axisymmetric viscous fluid flows. The purpose of the study was to test the correspondence between the pattern of changes in the viscoelastic characteristics of the aorta walls and the conditions of the self-organization of the tornado-like flow in its lumen. Three independent methods, namely, postmortal elastometry, intravital panaortography, and MSCT of a healthy volunteer, have been used to show that the aorta elasticity monotonically decreases in the distal direction, this relationship being distorted with increasing radial load beyond the physiologically normal range. This distribution of elasticity along the aorta ensures that the geometric configuration of the aorta flow pass corresponds to the directions of the current lines of the tornado-like flow obtained from the precise solutions throughout the cardiac cycle. Thus, it has been established that the changes in the elastic properties along the aorta create the necessary hydrodynamic conditions for maintaining the tornado-like flow throughout the cardiac cycle in the physiological range of pressure.