Cyclic pressure induced decellularization of porcine descending aortas.

The demand for decellularized xenogeneic tissues used in reconstructive heart surgery has increased over the last decades. Complete decellularization of longer and tubular aortic sections suitable for clinical application has not been achieved so far. The present study aims at analyzing the effect of pressure application on decellularization efficacy of porcine aortas using a device specifically designed for this purpose. Fresh porcine descending aortas of 8 cm length were decellularized using detergents. To increase decellularization efficacy, detergent treatment was combined with pressure application and different treatment schemes. Quantification of penetration depth as well as histological staining, scanning electron microscopy, and tensile strength tests were used to evaluate tissue structure. In general, application of pressure to aortic tissue does neither increase the decellularization success nor the penetration depth of detergents. However, it is of importance from which side of the aorta the pressure is applied. Application of intermittent pressure from the adventitial side does significantly increase the decellularization degree at the intimal side (compared to the reference group), but had no influence on the penetration depth of SDC/SDS at both sides. Although the present setup does not significantly improve the decellularization success of aortas, it is interesting that the application of pressure from the adventitial side leads to improved decellularization of the intimal side. As no adverse effects on tissue structure nor on mechanical properties were observed, optimization of the present protocol may potentially lead to complete decellularization of larger aortic segments.

Customized 3D printed bioreactors for decellularization-High efficiency and quality on a budget.

Decellularization (DC) of biomaterials with bioreactors is widely used to produce scaffolds for tissue engineering. This study uses 3D printing to develop efficient but low-cost DC bioreactors. Two bioreactors were developed to decellularize pericardial patches and vascular grafts. Flow profiles and pressure distribution inside the bioreactors were optimized by steady-state computational fluid dynamics (CFD) analysis. Printing materials were evaluated by cytotoxicity assessment. Following evaluation, all parts of the bioreactors were 3D printed in a commercial fused deposition modeling printer. Samples of bovine pericardia and porcine aortae were decellularized using established protocols. An immersion and agitation setup was used as a control. With histological assessment, DNA quantification and biomechanical testing treatment effects were evaluated. CFD analysis of the pericardial bioreactor revealed even flow and pressure distribution in between all pericardia. The CFD analysis of the vessel bioreactor showed increased intraluminal flow rate and pressure compared to the vessel's outside. Cytotoxicity assessment of the used printing material revealed no adverse effect on the tissue. Complete DC was achieved for all samples using the 3D printed bioreactors while DAPI staining revealed residual cells in aortic vessels of the control group. Histological analysis showed no structural changes in the decellularized samples. Additionally, biomechanical properties exhibited no significant change compared to native samples. This study presents a novel approach to manufacturing highly efficient and low budget 3D printed bioreactors for the DC of biomaterials. When compared to standard protocols, the bioreactors offer a cost effective, fast, and reproducible approach, which vastly improves the DC results.

Gigantic biatrial myxoma in a young female with an atrial septal defect: a case report.

Background: Myxomas are uncommon and benign cardiac neoplasms that can present with various cardiac, systemic, embolic, or without symptoms depending on their location and size. Very few cases of large, truly biatrial, or tumours connected via the cardiac atria have been reported throughout the years. Case summary: We present an unusual case of an apparently healthy 25-year-old French woman, who presented with dyspnoea at Munich's Octoberfest. Echocardiography and computed tomography identified gigantic masses in left and right atrium, which were connected through an atrial septal defect. They were successfully removed by emergent cardiac surgery. Discussion: This case describes an uncommon tumour and highlights the importance of a quick diagnosis and prompt surgery. We describe the management and surgery for atrial myxomas as well as demonstrating pre- and intraoperative pictures.

New perspectives in patient education for cardiac surgery using 3D-printing and virtual reality.

Background: Preoperative anxiety in cardiac surgery can lead to prolonged hospital stays and negative postoperative outcomes. An improved patient education using 3D models may reduce preoperative anxiety and risks associated with it. Methods: Patient education was performed with standardized paper-based methods (n = 34), 3D-printed models (n = 34) or virtual reality models (n = 31). Anxiety and procedural understanding were evaluated using questionnaires prior to and after the patient education. Additionally, time spent for the education and overall quality were evaluated among further basic characteristics (age, gender, medical expertise, previous non-cardiac surgery and previously informed patients). Included surgeries were coronary artery bypass graft, surgical aortic valve replacement and thoracic aortic aneurysm surgery. Results: A significant reduction in anxiety measured by Visual Analog Scale was achieved after patient education with virtual reality models (5.00 to 4.32, Δ-0.68, p < 0.001). Procedural knowledge significantly increased for every group after the patient education while the visualization and satisfaction were best rated for patient education with virtual reality. Patients rated the quality of the patient education using both visualization methods individually [3D and virtual reality (VR) models] higher compared to the control group of conventional paper-sheets (control paper-sheets: 86.32 ± 11.89%, 3D: 94.12 ± 9.25%, p < 0.0095, VR: 92.90 ± 11.01%, p < 0.0412). Conclusion: Routine patient education with additional 3D models can significantly improve the patients' satisfaction and reduce subjective preoperative anxiety effectively.

In vitro evaluation of the optimal degree of oversizing of thoracic endografts in prosthetic landing areas: a pilot study.

Objective: The optimal degree of proximal thoracic endograft oversizing when aiming for durable sealing in prosthetic grafts is unknown. The aim of the present study was to create an in vitro model for testing different oversized thoracic endografts in a reproducible and standardized manner and, subsequently, determine the optimal oversizing range when planning procedures with a proximal landing in prosthetic zones in the descending thoracic aorta or aortic arch. Methods: An in vitro model consisting of a fixed 24-mm polyethylene terephthalate (Dacron; DuPont) graft sutured proximally and distally to two specifically designed 40-mm rings, with four force sensing resistors attached at four equally distant positions and a USB camera attached proximally for photographic and video documentation was used for deployment of Zenith TX2 (Cook Medical Inc) dissection platform endografts with diameters between 24 and 36 mm. After deployment, ballooning with a 32-mm compliant balloon was performed to simulate real-life conditions. The assessment of oversizing included visual inspection, calculation of the valley areas created between the prosthetic wall and the stent graft fabric, distance between the stent graft peaks, the radial force exerted by the proximal sealing stent, and the pull-out force necessary for endograft extraction. Results: A total of 70 endografts were deployed with the oversizing ranging from 0% to 50%: 10 × 24 mm, 10 × 26 mm, 10 × 28 mm, 10 × 30 mm, 10 × 32 mm, 10 × 34 mm, and 10 × 36 mm. Two cases of infolding occurred with 50% oversizing. The valley areas increased from 8.79 ± 0.23 mm2 with 16.7% oversizing to 14.26 ± 0.45 mm2 with 50% oversizing (P < .001). A significant difference was found in the pull-out force required for endografts with <10% oversizing vs ≥10% oversizing (P < .001). The difference reached a plateau at ∼4 N with oversizing of >15%. The mean radial force of the proximal sealing stent was greater after remodeling with a compliant balloon (0.55 ± 0.02 N vs 0.60 ± 0.02 N after ballooning; P < .001). However, greater oversizing did not lead to an increase in the radial force exerted by the proximal sealing stent. Conclusions: The findings from the present study offer additional insight into the mechanics of oversized stent grafts in surgical grafts. In endografts with the Zenith stent design (TX2), oversizing of <16.7% resulted in reduced resistance to displacement forces, and oversizing of >50% was associated with major infolding in 20% of cases. Long-term in vitro and in vivo testing is required to understand how these mechanical properties affect the clinical outcomes of oversizing.

Combining 3D-Printing and Electrospinning to Manufacture Biomimetic Heart Valve Leaflets.

Electrospinning has become a widely used technique in cardiovascular tissue engineering as it offers the possibility to create (micro-)fibrous scaffolds with adjustable properties. The aim of this study was to create multilayered scaffolds mimicking the architectural fiber characteristics of human heart valve leaflets using conductive 3D-printed collectors. Models of aortic valve cusps were created using commercial computer-aided design (CAD) software. Conductive polylactic acid was used to fabricate 3D-printed leaflet templates. These cusp negatives were integrated into a specifically designed, rotating electrospinning mandrel. Three layers of polyurethane were spun onto the collector, mimicking the fiber orientation of human heart valves. Surface and fiber structure was assessed with a scanning electron microscope (SEM). The application of fluorescent dye additionally permitted the microscopic visualization of the multilayered fiber structure. Tensile testing was performed to assess the biomechanical properties of the scaffolds. 3D-printing of essential parts for the electrospinning rig was possible in a short time for a low budget. The aortic valve cusps created following this protocol were three-layered, with a fiber diameter of 4.1 ± 1.6 µm. SEM imaging revealed an even distribution of fibers. Fluorescence microscopy revealed individual layers with differently aligned fibers, with each layer precisely reaching the desired fiber configuration. The produced scaffolds showed high tensile strength, especially along the direction of alignment. The printing files for the different collectors are available as Supplemental File 1, Supplemental File 2, Supplemental File 3, Supplemental File 4, and Supplemental File 5. With a highly specialized setup and workflow protocol, it is possible to mimic tissues with complex fiber structures over multiple layers. Spinning directly on 3D-printed collectors creates considerable flexibility in manufacturing 3D shapes at low production costs.