Ex-vivo biomechanical characterization of porcine cava vein

In recent years, percutaneous procedures are gradually replacing open heart surgery for the treatment of tricuspid valve pathological conditions deploying prosthetic devices (i.e., stent-graft) within the proximal portion of the cava veins. Nevertheless, since there is no comprehensive mechanical characterization of the venous district, the devices exploited in these procedures are very similar to the ones exploited in aortic treatment, involving possible critical periprocedural complications. According to the international standards adopted for the design of novel vascular devices, this study presents an experimental set-up to investigate the biomechanics of fifteen porcine cava veins with the development of a semi-automatic protocol for compliance testing. During the tests, 2D echo images of the vessel lumen are acquired for different steps within a pressure range of 5-20 mmHg. The acquired pressure-diameter curves of the samples are then derived by a polynomial function, furthermore, the compliance values are obtained using the corresponding equations as well. The results demonstrate that the cava vein exhibits a hyperelastic behavior, with a nonlinear relationship between pressure and diameter. At low pressures, the veins demonstrate high compliance and reduced stiffness (11.54 ± 4.76 kPa). On the contrary, when pressures exceed the normal physiological range (i.e., greater than 10 mmHg), the veins become stiffer (294.70 ± 233.00 kPa). The developed set-up, based on an ex-vivo porcine model, proved to be a robust tool for the assessment of vein biomechanics and for preclinical benchmarking of novel venous endovascular devices.