Wood Fibre Materials on Hot Sounding Rocket Structures

Throughout the history of aviation as well as space flight, wooden materials played a major role in the construction of primary as well as secondary structures. Being one of the first construction materials used in that field, it does not only offer low density and good relative strength properties, but also easy handling, simple production processes, low costs and last but not least a green, renewable resource. With its unique characteristics the worlds lightest and biggest aviation vehicles heavier than air were created. Because of its relatively low thermal conductivity and good ablative behaviour wooden materials are taken into consideration for the use of hot structures such as the leading edges of sounding rocket stabilising fins. As a mandatory and thus flight critical structure of ballistic flying vehicles, fins need to be aerodynamically effective, lightweight, stiff and heat resistant on its foremost front end, where high temperatures may arise from fluid stagnation and friction. In order to gain a deeper understanding and assess the usability of modern wood fibre materials being appropriate in that field jointly, a cooperation with the Technische Universität Dresden (TUD) and the German Aerospace Center (DLR) has been established. This paper describes the motivation of the research as well as the structural application with its functionality and boundary conditions. The choice of materials and its rationale for selection in combination with various screening test results are the core of this research. First impacts on the components´ design and an outlook for future research conclude this paper

Bio-based ablative thermal protection materials for space application

In the context of a growing bioeconomy, green renewable resources are of interest for the space industry. Because of its relatively low density, low thermal conductivity, easy handling and good ablative behaviour bio- and wood-based materials are taken into consideration for the use as a thermal protection system (TPS) material on hot structures such as the leading edges of stabilising fins, fairings, nose cones and other TPS applications. As a mandatory and thus flight critical structure of launch vehicles, these parts need to be aerodynamically effective, lightweight, stiff and heat resistant on its foremost front end, where high temperatures may arise from gas kinetic effects. In order to gain a deeper understanding and assess the applicability of modern bio- and wood-based materials, a systematic literature and patent analysis of bio- and wood-based materials in spaceflight has been conducted as a starting point for the research. To set a framework for the application of a bio-based material in space, functionality and boundary conditions have been analysed and form requirements for the development of the bio-based TPS material. Further, prototype materials with varying ingredients of natural fibres, binders and additives have been developed and characterised by a thermogravimetric analysis (TGA) to determine their general suitability as a TPS material. The materials have been additionally screened in more detail via the analyses of bulk density, thermal conductivity and specific heat capacity. Measurements under real environmental conditions in a plasma channel were carried out for further investigation and form the core of this work. With the defined requirements and results from screening tests and plasma channel tests a selection of the best-performing prototype material could be made. First impacts on launch vehicle’s design and an outlook for future research on bio-based TPS conclude this contribution

Procedural and one-year outcomes of the BASILICA technique in Europe: the multicentre EURO-BASILICA registry.

BACKGROUND The real-world outcomes of the use of the BASILICA (Bioprosthetic or Native Aortic Scallop Intentional Laceration to Prevent Iatrogenic Coronary Artery Obstruction) transcatheter technique in Europe have not been described. AIMS We sought to evaluate the procedural and one-year outcomes of BASILICA in patients at high risk for coronary artery obstruction (CAO) undergoing transcatheter aortic valve implantation (TAVI) in a multicentre European registry (EURO-BASILICA). METHODS Seventy-six patients undergoing BASILICA and TAVI at ten European centres were included. Eighty-five leaflets were identified as targets for BASILICA due to high risk for CAO. The updated Valve Academic Research Consortium 3 (VARC-3) definitions were used to determine prespecified endpoints of technical and procedural success and adverse events up to one year. RESULTS Treated aortic valves included native (5.3%), surgical bioprosthetic (92.1%) and transcatheter valves (2.6%). Double BASILICA (for both left and right coronary cusps) was performed in 11.8% of patients. Technical success with BASILICA was achieved in 97.7% and resulted in freedom from any target leaflet-related CAO in 90.6% with a low rate of complete CAO (2.4%). Target leaflet-related CAO occurred significantly more often in older and stentless bioprosthetic valves and with higher implantation levels of transcatheter heart valves. Procedural success was 88.2%, and freedom from VARC-3-defined early safety endpoints was 79.0%. One-year survival was 84.2%; 90.5% of patients were in New York Heart Association Functional Class I/II. CONCLUSIONS EURO-BASILICA is the first multicentre study evaluating the BASILICA technique in Europe. The technique appeared feasible and effective in preventing TAVI-induced CAO, and one-year clinical outcomes were favourable. The residual risk for CAO requires further study

Early Clinical Experience With the TRICENTO Bicaval Valved Stent for Treatment of Symptomatic Severe Tricuspid Regurgitation: A Multicenter Registry.

BACKGROUND Patients with severe tricuspid regurgitation present late and are often ineligible for surgery or transcatheter repair systems. Transfemoral venous implantation of a bicaval valved stent has been proposed as therapeutic option in selected patients. The aim of this study was to summarize the early procedural and clinical outcomes of the novel TRICENTO system for the treatment of patients with symptomatic severe tricuspid regurgitation. METHODS All consecutive patients treated with the custom-made TRICENTO implant at the participating centers were included in this retrospective multicentre registry. RESULTS A total of 21 high-risk patients (mean age 76±7 years; 67% female) with severe or higher grade tricuspid regurgitation were analyzed. The majority of the patients were in New York Heart Association class III/IV (95%), had peripheral edema (95%), and previous hospitalization for right heart failure (67%). Technical success was 100%, and there was no case of in-hospital mortality. During follow-up (median 61 days), symptomatic improvement was observed (65% in New York Heart Association class I/II; P<0.001). Computed tomography revealed asymptomatic fractures of the TRICENTO prosthesis in 3 patients. Cardiac magnetic resonance imaging obtained in 7 patients showed a significant decrease (252±65 mm3 at baseline versus 216±58 mm3 at follow-up, P=0.006) of right ventricular end-diastolic volume. The overall-survival rate was 76% at 1 year. CONCLUSIONS The present data indicate the feasibility of transfemoral bicaval valved stent implantation for the treatment of severe tricuspid regurgitation. Functional improvement and signs of right ventricular reverse remodeling were observed. Stent fractures did not impair valve function, but require refinement of prosthesis design and careful assessment of eligibility criteria

Chimney Stenting vs BASILICA for Prevention of Acute Coronary Obstruction During Transcatheter Aortic Valve Replacement

Background: Coronary obstruction (CO) is a potentially life-threatening complication of transcatheter aortic valve replacement (TAVR). Chimney stenting or leaflet laceration with transcatheter electrosurgery (Bioprosthetic or Native Aortic Scallop Intentional Laceration to Prevent Iatrogenic Coronary Artery Obstruction [BASILICA]) are 2 techniques developed to prevent CO. Objectives: The aim of the present study was to compare periprocedural and 1-year outcomes of chimney and BASILICA in TAVR patients at high risk of CO. Methods: This multicenter observational registry enrolled consecutive TAVR patients at high risk of CO, undergoing either preventive chimney stenting or BASILICA. Clinical success was defined as successful performance of the chimney or BASILICA technique without clinically relevant ostial CO. The primary endpoint was major adverse cardiovascular events, a composite of death, myocardial infarction, stroke, or unplanned target lesion coronary revascularization at 1 year. Results: A total of 168 patients were included: 71 (42.3%) received chimney stenting, and 97 (57.7%) underwent BASILICA. Patients undergoing BASILICA had higher preprocedural risk of CO, as indicated by lower sinotubular junction height (18.2 ± 4.8 mm vs 14.8 ± 3.4 mm; P &lt; 0.001) and diameter (28.2 ± 4.5 vs 26.8 ± 3.4; P = 0.029). Rates of periprocedural complications were similar between the 2 groups. Clinical success was 97.2% and 96.9% in chimney and BASILICA, respectively (P = 0.92). At 1-year follow-up, the cumulative incidence of major adverse cardiovascular events was 18.7% (95% CI: 11%-30.6%) in the chimney group and 19.9% (95% CI: 12.1%-31.5%) in the BASILICA group (log-rank P = 0.848), whereas chimney was associated with a numerically higher cardiovascular mortality than BASILICA (6.7% vs 1.3%; log-rank P = 0.168). Conclusions: Chimney stenting and BASILICA effectively prevent TAVR-induced acute CO. Both techniques seem to have comparable acceptable periprocedural and 1-year outcomes.</p

Chimney Stenting vs BASILICA for Prevention of Acute Coronary Obstruction During Transcatheter Aortic Valve Replacement

Background: Coronary obstruction (CO) is a potentially life-threatening complication of transcatheter aortic valve replacement (TAVR). Chimney stenting or leaflet laceration with transcatheter electrosurgery (Bioprosthetic or Native Aortic Scallop Intentional Laceration to Prevent Iatrogenic Coronary Artery Obstruction [BASILICA]) are 2 techniques developed to prevent CO. Objectives: The aim of the present study was to compare periprocedural and 1-year outcomes of chimney and BASILICA in TAVR patients at high risk of CO. Methods: This multicenter observational registry enrolled consecutive TAVR patients at high risk of CO, undergoing either preventive chimney stenting or BASILICA. Clinical success was defined as successful performance of the chimney or BASILICA technique without clinically relevant ostial CO. The primary endpoint was major adverse cardiovascular events, a composite of death, myocardial infarction, stroke, or unplanned target lesion coronary revascularization at 1 year. Results: A total of 168 patients were included: 71 (42.3%) received chimney stenting, and 97 (57.7%) underwent BASILICA. Patients undergoing BASILICA had higher preprocedural risk of CO, as indicated by lower sinotubular junction height (18.2 ± 4.8 mm vs 14.8 ± 3.4 mm; P &lt; 0.001) and diameter (28.2 ± 4.5 vs 26.8 ± 3.4; P = 0.029). Rates of periprocedural complications were similar between the 2 groups. Clinical success was 97.2% and 96.9% in chimney and BASILICA, respectively (P = 0.92). At 1-year follow-up, the cumulative incidence of major adverse cardiovascular events was 18.7% (95% CI: 11%-30.6%) in the chimney group and 19.9% (95% CI: 12.1%-31.5%) in the BASILICA group (log-rank P = 0.848), whereas chimney was associated with a numerically higher cardiovascular mortality than BASILICA (6.7% vs 1.3%; log-rank P = 0.168). Conclusions: Chimney stenting and BASILICA effectively prevent TAVR-induced acute CO. Both techniques seem to have comparable acceptable periprocedural and 1-year outcomes.</p