Biological bioprostheses such as grafts, patches, and heart valves are often derived from biological tissue like the pericardium. These bioprostheses can be of xenogenic, allogeneic, or autologous origin. Irrespective of their origin, all types are pre-treated via crosslinking to render the tissue non-antigenic and mechanically strong or to minimize degradation. The most widely used crosslinking agent is glutaraldehyde. However, glutaraldehyde-treated tissue is prone to calcification, inflammatory degradation, and mechanical injury, and it is incapable of matrix regeneration, leading to structural degeneration over time. In this work, we are investigating an alternative crosslinking method for an intraoperative application. The treated tissue‘s crosslinking degree was evaluated by differential scanning calorimetry. To confirm the findings, a collagenase assay was conducted. Uniaxial tensile testing was used to assess the tissue’s mechanical properties. To support the findings, the treated tissue was visualized using two-photon microscopy. Additionally, fourier transform infrared spectroscopy was performed to study the overall protein secondary structure. Finally, a crosslinking procedure was identified for intraoperative processing. The samples showed a significant increase in thermal and enzymatic stability after treatment compared to the control, with a difference of up to 22.2 °C and 100%, respectively. Also, the tissue showed similar biomechanics to glutaraldehyde-treated tissue, showing greater extensibility, a higher failure strain, and a lower ultimate tensile strength than the control. The significant difference in the structure band ratio after treatment is proof of the introduction of additional crosslinks compared to the untreated control with regard to differences in the amide-I region. The microscopic images support these findings, showing an alteration of the fiber orientation after treatment. For collagen-based biomaterials, such as pericardial tissue, the novel phenolic crosslinking agent proved to be an equivalent alternative to glutaraldehyde regarding tissue characteristics. Although long-term studies must be performed to investigate superiority in terms of longevity and calcification, our novel crosslinking agent can be applied in concentrations of 1.5% or 2.0% for the treatment of biomaterials.

Transcatheter heart valve replacements (TVR) are mostly designed in a closed position (c) with leaflets coaptating. However, recent literature suggests fabricating valves in semi-closed (sc) position to minimize pinwheeling. With about 100,000 children in need of a new pulmonary valve each year worldwide, this study evaluates both geometrical approaches in adult as well as pediatric size and condition. Three valves of each geometry were fabricated in adult (30 mm) and pediatric (15 mm) size, using porcine pericardium. To evaluate performance, the mean transvalvular pressure gradient (TPG), effective orifice area (EOA), and regurgitation fraction (RF) were determined in three different annulus geometries (circular, elliptic, and tilted). For both adult-sized valve geometries, the TPG (TPG_C = 2.326 ± 0.115 mmHg; TPG_SC = 1.848 ± 0.175 mmHg)* and EOA (EOA_C = 3.69 ± 0.255 cm²; EOA_SC = 3.565 ± 0.025 cm²)* showed no significant difference. Yet the RF as well as its fluctuation was significantly higher for valves with the closed geometry (RF_C = 12.657 ± 7.669 %; RF_SC = 8.72 ± 0.977 %)*. Recordings showed that the increased backflow was caused by pinwheeling due to a surplus of tissue material. Hydrodynamic testing of pediatric TVRs verified the semi-closed geometry being favourable. Despite the RF (RF_C = 7.721 ± 0.348 cm²; RF_SC = 5.172 ± 0.679 cm²), these valves also showed an improved opening behaviour ((TPG_C = 20.929 ± 0.497 cm²; TPG_SC = 15.972 ± 1.158 cm²); (EOA_C = 0.629 ± 0.017 cm²; EOA_SC = 0.731 ± 0.026 cm²)). Both adult and pediatric TVR with semi-closed geometry show better fluiddynamic functionality compared to valves with a closed design due to less pinwheeling. Besides improved short-term functionality, less pinwheeling potentially prevents early valve degeneration and improves durability. *Results are representatively shown for a circular annulus geometry.

Introduction: Valvular heart disease remains a leading cause of morbidity and mortality. Current biological and mechanical heart valve prostheses have significant limitations and fail to address the patient's needs. Most of the limitations arise from the use of foreign materials, which can largely be addressed by utilizing autologous pericardial tissue. However, not all patients have usable pericardium due to previous interventions. This study investigates peritoneum as a potential alternative to pericardium and evaluates an optimized treatment method for intraoperative tissue treatment. Methods: A previously established cross‐linking method was optimized and applied to pericardial and peritoneal tissues. The tissues were characterized with respect to biochemical composition, cross‐linking degree, biomechanical properties, and structural organization. Furthermore, the feasibility of valve shaping was assessed, and constructs were subjected to acute hydrodynamic testing. Results: Tissue treated with the optimized cross‐linking method showed high cytocompatibility and was successfully applied to peritoneal tissue. Compared to pericardium, peritoneum exhibited a higher elastin content and a looser structural organization, resulting in distinct mechanical behavior. Both tissues could be shaped into valve constructs showing adequate acute hydrodynamic behavior under the applied test conditions. Conclusion: The findings suggest that the peritoneum is a promising candidate material for further investigation as a heart valve scaffold. However, differences in microstructure and mechanical behavior highlight the need for further testing, particularly regarding long‐term durability, cyclic loading behavior, and tissue remodeling capacity.

Purpose: Transcatheter heart valve replacements (TVR) are typically designed in a closed shape with initial leaflet coaptation. However, recent studies suggest a semi-closed geometry without a predefined coaptation zone, relying on diastolic pressure and clinical oversizing of 10–20 % for closure. This approach may minimize pinwheeling, a phenomenon linked to early valve degeneration. Method: Seven valve geometries were assessed: one closed design (G0) and six semi-closed variations (G1–G6). The semi-closed designs differed in free edge shape (linear, concave, convex) and opening degree, defined as the relative distance from the leaflet to the valve center in the unloaded state. The opening degree was systematically increased across G1–G6, with G6 exhibiting the highest value. 30 mm valves were fabricated using porcine pericardium and self-expanding nitinol stents. Performance was assessed in a pulse duplicator system, evaluating transvalvular pressure gradient (TPG), effective orifice area (EOA), regurgitation fraction (RF) and a novel pinwheeling index (PI) which was validated by finite element simulations. Results: Finite element simulations demonstrated that semi-closed geometries achieve valve closure at a diameter reduction of >5%. In vitro tests confirmed these findings with more homogeneous coaptation and reduced pinwheeling. With increased opening degree the RF reduced significantly (RF_G0 = 18.54 ± 8.05%; RF_G6 = 8.22 ± 1.27%; p < 0.0001), while valve opening remained comparable (p = 0.4519). Conclusions: A semi-closed leaflet geometry enhances valve closure, reducing regurgitation and pinwheeling while preserving effective opening. With clinical oversizing, a higher opening degree improves coaptation and may enhance durability by mitigating structural deterioration, ultimately improving the long-term performance and lifespan of transcatheter valve replacements.