Mechanical Characterization of Porcine Cardiac Tissue for the Development of a Polymeric Model of Right Heart

Background: In recent years, the growth in the development of new cardiovascular devices, coupled with the ethical concerns and the limited availability of animal cardiac tissue, has highlighted the need to replace animal tissue with polymeric models for testing devices under realistic conditions. Currently, in laboratory settings, devices are tested using animal cardiac models harvested from slaughterhouses and frozen until the time of testing. This procedure may affect the mechanical properties of the tissue, resulting in a testing environment different from the physiological conditions. Therefore, the purpose of this work is to mechanically characterize porcine cardiac tissue to identify suitable polymeric materials for developing realistic replica of the right heart. Methods: Five freshly harvested and five thawed porcine right hearts were mechanically characterized. For each right heart, three samples from interventricular septum (S1, S2, S3) and free wall (FW1, FW2, FW3) were excised, as shown in Figure 1, obtaining 30x30 mm samples, and tested under compression. The thickness of each sample was measured, and the elastic modulus (E) was calculated. Nine different combinations of silicones and non-reactive silicone fluid, as described in Table 1, were mechanically characterized. For each combination, three samples (30x30 mm) with the same thickness of interventricular septum and free wall were tested under compression and the elastic modulus (E) was compared with that derived from tested cardiac tissue. Results: A statistically significant difference was observed between elastic modulus of thawed (E=0.42MPa) and fresh (E=0.51MPa, p<0.0001) free wall samples and between thawed (E=0.44MPa) and fresh (E=0.47MPa, p<0.01) interventricular septum samples. No statistically significant differences emerged among different regions tested. The silicone that replicated the fresh free wall’s mechanical properties was Ecoflex 00-50 (0.46 ± 0.04 MPa), while Dragon Skin 10 (Thinner 10% wt) (0.49 ± 0.02 MPa) was identified for fresh interventricular septum. Conclusions: In conclusion, the ability to replicate the mechanical properties of cardiac tissue with polymeric materials would enable the development of a realistic right heart model, which could serve as a valuable tool for testing medical devices in the early-stage phase. This polymeric model not only can offer a sustainable alternative but also can provide the flexibility to replicate various cardiac conditions, improving simulations’ fidelity.