Rouven Berndt

Background: TAVI indications expand not only to low-risk patients but also to patients with a more complex anatomy and comorbidities. Transfemoral retrograde access is recognized as the first preferred approach according to the current guidelines. However, this approach is not suitable in up to 10–15% of patients, for whom an alternative non-femoral access route is required. Case Presentation: An 83-year-old male patient with known aortic isthmus stenosis presented with severe symptomatic aortic stenosis. Computed tomography revealed a subtotal isthmus stenosis, directly after left subclavian artery origin, with many collaterals extending toward the axillary and subclavian arteries. Duplex ultrasound verified the proximal diameter of the left brachial artery to be 5.5 mm. A successful surgical cutdown trans-brachial TAVI with an Evolut prosthetic valve with a size of 29 mm was performed. On the fourth postoperative day, the patient was discharged, and the three-month follow-up was uneventful. Conclusion: In patients with aortic isthmus stenosis, the brachial artery could be a feasible alternative, as a less invasive access site, which can be determined after careful assessment of the vessel diameter. More data are required to evaluate the safety and efficacy of this access route and to achieve more technical improvements to increase operator familiarity with it.

One of the most important medical interventions for individuals with heart valvular disease is heart valve replacement, which is not without substantial challenges, particularly for pediatric patients. Due to their biological properties and biocompatibility, natural tissue-originated scaffolds derived from human or animal sources are one type of scaffold that is widely used in tissue engineering. However, they are known for their high potential for immunogenicity. Being free of cells and genetic material, decellularized xenografts, consequently, have low immunogenicity and, thus, are expected to be tolerated by the recipient’s immune system. The scaffold ultrastructure and ECM composition can be affected by cell removal agents. Therefore, applying an appropriate method that preserves intact the structure of the ECM plays a critical role in the final result. So far, there has not been an effective decellularization technique that preserves the integrity of the heart valve’s ultrastructure while securing the least amount of genetic material left. This study demonstrates a new protocol with untraceable cells and residual DNA, thereby maximally reducing any chance of immunogenicity. The mechanical and biochemical properties of the ECM resemble those of native heart valves. Results from this study strongly indicate that different critical factors, such as ionic detergent omission, the substitution of Triton X-100 with Tergitol, and using a lower concentration of trypsin and a higher concentration of DNase and RNase, play a significant role in maintaining intact the ultrastructure and function of the ECM.

A novel developed 4D bioprinting technique is used for the manufacturing of human‐scale, small‐diameter vascular grafts. Accordingly, a bio‐ink is synthesized from a hybrid molecule containing sodium alginate (SA) and collagen peptide (COP). Endothelial progenitor cells (EPC) isolated from human whole blood are integrated into the bioartificial vascular graft as an autologous cell source. Likewise, human umbilical vein endothelial cells (HUVEC) are used as experimental standard. The evolving vascular grafts are printed by a customized 4D bioprinter into CaCl 2 support medium for rapid cross‐linking inducing the temporospatial shaping of the grafts. After culturing for 21 days, histological and ultrastructural analyses of the bioartificial vascular grafts reveal a well‐organized matrix with imbedded EPC or HUVEC. Live‐3D‐cell–imaging and cell viability assays demonstrate a multitude of vital and metabolically active cells. Biomechanics of the grafts are proven to be comparable to human saphenous veins. Coagulation analysis reveals low thrombogenicity and high functional integrity of the vascular grafts. Surgical implantation of the grafts in a perfused cadaver model can be performed effectively and without technical issues. Finally, the current study describes for the first time the 4D bioprinting and characterization of a small‐diameter, human‐scale vascular graft for putative clinical translation.