Mechanical tissue changes caused by liquid jet blasting of the aortic cannula

The aim of this study is to investigate the mechanical influence on the aortic tissue when exposed to the liquid jet blasting effect produced by the aortic cannula during cardiothoracic surgery. Aortic tissue from seven porcine hearts was exposed to a continuous liquid jet from an aortic cannula positioned in a simple flow loop. After 4 h of exposure, samples were obtained from the aortic root using a twin punch device. Additionally, tissue was harvested from seven untouched aortic roots serving as our control group. Uniaxial tensile testing was conducted to measure the ultimate strength and Young's modulus. Furthermore, we analysed the samples using dynamic mechanical analysis in the frequency range from 0.5 to 5 Hz. There were no significant differences in ultimate tensile strength or Young's modulus between the test group and control group. Dynamic mechanical analysis revealed significant increases in both mean storage modulus (44%) and mean loss modulus (73%) in the exposed samples. There was a tendency towards higher tanδ in the test group, suggesting altered viscoelastic behaviour. These findings indicates that the liquid jet exposure influences the viscoelastic properties of the aortic wall and makes it stiffer. Further studies should incorporate histological and microstructural analyses to confirm mechanical alterations at the tissue level. Clinically, such changes may contribute to local wall injury, altered flow dynamics, or plaque destabilisation during cardiopulmonary bypass. This highlighting the need for optimisation of cannula flow direction and velocity to minimise the mechanical impact on the aortic wall.