Selection of Parameters for Optimized WAAM Structures for Civil Engineering Applications.

Using the CMT (Cold Metal Transfer, F. Fronius, Upper Austria) welding process, wire arc additive manufacturing (WAAM) enables companies to fabricate steel components in a resource-saving manner (additive vs. subtractive) by properly reinforcing existing steel components. Two fundamental questions are discussed in the current work. The first focus is on the general geometric possibilities offered by this process. The influence of various parameters, such as wire feed speed, travel speed, and torch inclination on the seam shape and build-up rate are presented. The microstructure of the manufactured components is evaluated through metallography and hardness testing. Based on the first results, print strategies are developed for different requirements. Moreover, suitable process parameter sets are recommended in terms of energy input per unit length, weld integrity and hardness distribution. The second focus is on testing and determining joint properties by analyzing the microhardness of the welded structures. The chosen parameter sets will be investigated, and steel quality equivalents according to ÖNORM EN ISO 18265 will be defined.

David V procedure and hemiarch replacement in a patient with Loeys-Dietz-Syndrome and beta thalassemia minor: a case report.

We report the case of a 36-year-old European female patient presenting with a sinus valsalva aneurysm of 47 mm with moderate aortic regurgitation. Additionally, an aneurysm of the brachiocephalic trunk and multiple aneurysms of the right internal mammary artery were identified. Previous medical history included Loeys-Dietz syndrome (LDS) Type RII due to a TGF-beta receptor mutation, and beta thalassemia minor with a baseline hemoglobin of 9,3 g/dL on admission.Reconstruction of the aortic root and hemiarch replacement was performed in circulatory arrest under moderate hypothermia. During surgery, hypothermia was required as part of the cerebral protection strategy. We aim to highlight special considerations and discuss the effects of cooling, rewarming and the use of cardiopulmonary bypass (CPB) during extensive surgery in a patient with LDS and beta thalassemia minor.

Reduction ascending aortoplasty: A retrospective analysis of outcomes and risk factors.

Objectives: Indication for Reduction of Ascending Aortoplasty (RAA) and long-term outcomes remain unclear. This study analyzed the outcomes after nonreinforced RAA in two Austrian centers. Methods: Patients with RAA at two Austrian centers between 6/2,009 and 6/2,017 were retrospectively analyzed. Aortic diameters were measured by CT pre- and post-operatively. Patients were assigned according to valve morphology and imaging modality. Results: Overall, 253 patients underwent RAA [women: 30.8%; median age 74 (63-79) years] with a mean preoperative ascending diameter of 44.7 (±3.5) mm. RAA-related postoperative adverse events occurred in 1.2% (n = 3) over a follow-up of a median of 3.8 (2.4-5.5) years: One type A aortic dissection, one lethal aortic rupture at the suture line, and one suture line bleeding with cardiac tamponade and need of surgical revision. The overall survival rate was 89.7%. Aortic valve morphology itself was no risk factor for mortality (Log-Rank: 0.942). One hundred and forty patients had a tricuspid [TAV: (55.3%)] aortic valve and 113 patients had a bicuspid aortic valve [BAV: (44.7%)]. Redilatation to a diameter >50 mm according to CT follow-up occurred in 5.7% (n = 5 of 87). One patient needed reoperation with RAA and aortic valve replacement due to a prosthesis-patient mismatch after aortic valve replacement and aortic redilatation. Conclusion: Non-reinforced RAA is a safe, feasible, and reproducible procedure with low rates of perioperative complications in selected patients primarily undergoing aortic valve repair with a dilated ascending aorta. Aortic valve morphology has no impact on mortality after RAA.

Idiopathic pulmonary artery aneurysm.

A 60-year-old male being treated for chronic venous stasis ulcers presented with an asymptomatic pulmonary artery aneurysm involving the main pulmonary trunk and extending into both pulmonary arteries. He underwent successful resection of the aneurysm, and his chronic ulcerations recovered spontaneously. Surgical treatment of pulmonary artery aneurysm could be found in reports from Wilms and Sauerbruch dating from the early twenties of the last century. In 1950, Blades et al. reported a ligation of an aneurysmatic pulmonary artery with lung resection. However, the role of surgery in main pulmonary artery aneurysms is still not well defined. In this report, we describe the management of an extensive pulmonary artery aneurysm in a patient with chronic venous stasis ulcers.

Short-term clinical outcomes for intermittent cold versus intermittent warm blood cardioplegia in 2200 adult cardiac surgery patients.

BACKGROUND: Aim of the present study was to compare clinical outcome of intermittent cold (ICC) versus intermittent warm (IWC) blood cardioplegia in different cardiosurgical procedures. METHODS: Two thousand one hundred and eighty-eight patients were retrospectively divided into 5 groups: isolated coronary artery bypass surgery (CABG; N.=1203), isolated aortic valve surgery (AVR; N.=374), isolated mitral valve surgery (MVR; N.=151), combined AVR+CABG (N.=390), and combined MVR+CABG (N.=70). Myocardial protection was performed by ICC (N.=1578) or IWC (N.=610) blood cardioplegia. In logistic regression models the effect of cardioplegia on 30-day mortality, IABP/ECLS (intraaortic balloon-pump/extracorporal life support) implantation, transient neurological deficit, stroke, renal failure, new-onset atrial fibrillation, and troponin T release was estimated. Potential modifications of the effect of cardioplegia by logistic EuroSCORE, cross-clamping time, ejection fraction, and op-status elective versus urgent/emergent were investigated. RESULTS: There were no statistically significant differences between ICC and IWC regarding 30-day mortality (odds ratio [OR]=0.70; 95% CI: 0.39-1.23; P=0.219), IABP/ECLS support (OR=0.60; 95% CI: 0.23-1.55; P=0.294), transient neurological deficit (OR=0.90; 95% CI: 0.65-1.24; P=0.541), stroke (OR=0.79; 95% CI: 0.40-1.54; P=0.495), renal failure (OR=1.07; 95% CI: 0.57-1.99; P=0.825), and atrial fibrillation (OR=0.96; 95% CI: 0.77-1.18; P=0.713) across all 5 groups. Troponin t release was significantly higher in ICC compared to IWC (by 0.029±0.015 ng/mL; P=0.046) in univariate analysis; this effect was lowered by risk-factor adjustment and lost statistical significance. The effect of cardioplegia was not significantly different between groups. In urgent/emergent surgery ICC resulted in a significantly higher 30-day mortality (OR=3.03; P=0.024) compared to IWC. CONCLUSIONS: The comparison of IWC and ICC blood cardioplegia in different cardiosurgical procedures showed no statistical significant difference in myocardial protection. The use of ICC, however, appeared overall associated with a slightly better clinical outcome except in patients undergoing urgent/emergent CABG where IWC led to a reduction in 30-day-mortality.

Type A dissection and chronic dilatation: tenascin-C as a key factor in destabilization of the aortic wall.

OBJECTIVES: Tenascin-C plays an important role in myocardial and vascular remodelling. We hypothesized that tenascin-C is a key factor in the development of degenerative disease of the ascending aorta, leading to chronic dilatation and acute aortic dissection. METHODS: Ascending aortic wall specimens were obtained during surgery for chronic dilatation (n=52) and acute Type A dissection (n=30). Patients (n=12) undergoing aortic valve replacement served as controls. Tenascin-C expression was evaluated by immunostaining and semi-quantitatively assessed using the ImageJ software. TN-C levels in peripheral blood were determined by enzyme-linked immunosorbent assay. RESULTS: Histological examination showed a clear difference between chronic dilatation and acute dissection. In chronic dilatation, tenascin-C staining was homogenously distributed throughout the media parallel to vascular smooth muscle cells. In acute dissection, a strong staining with a heterogenous and spotty distribution was detected. Control aortas showed no tenascin-C staining. Tenascin-C expression was significantly higher in Type-A dissection compared with chronic dilatation. This was accompanied by a significant elevation of tenascin-C levels in peripheral blood in acute dissection. There was no statistical correlation between the tenascin-C level in peripheral blood and the aortic diameter either in dissection or in dilatation. CONCLUSIONS: Tenascin-C is a marker of progressive destabilization of the aortic wall independent of size in chronic dilatation and acute dissection. Therefore, it might be a valuable tool in guiding intervention strategies in patients with disease of the ascending aorta.