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BackgroundStandardized methods for mapping the complex blood flow in vessels are essential for processing the large data volume acquired from 4D Flow MRI. We present a method for systematic and efficient analysis of anatomy and flow in large human blood vessels. To attain the best outcomes in cardiac surgery, vascular modifications that lead to secondary flow patterns such as vortices should be avoided. In this work, attention was paid to the undesired cancelation of vortices with opposite directions of rotation, known as Dean flow patterns, using hemodynamic parameters such as circulation and helicity density.MethodsOur approach is based on the multiplanar reconstruction (MPR) of a multi-dimensional feature-space along the blood vessel's centerline. Hemodynamic parameters and anatomic information were determined in-plane from the reconstructed feature-space and from the blood vessel's centerline. A modified calculation of circulation and helicity density and novel parameters for quantifying Dean flow were developed. To test the model performance, we applied our methods to three test cases.ResultsComprehensive information on position, magnitude and interrelation of vascular anatomy and hemodynamics were extracted from 4D Flow MRI datasets. The results show that the Dean flow patterns can be efficiently assessed using the novel parameters.ConclusionsOur approach to comprehensively and simultaneously quantify multiple parameters of vascular anatomy and hemodynamics from 4D Flow MRI provides new insights to map complex hemodynamic conditions.

The aim of this work is the adjustment of an advantageous compressive residual stress profile in hot-formed components by intelligent process control with tailored cooling from the forging heat. The feasibility and potential are demonstrated in a hot forming process in which cylindrical specimen with an eccentric hole are formed at 1000 °C and subsequently cooled in water from the forging heat. Previous work shows that tensile residual stresses occur in the specimen formed in this way from the material 1.3505. Using the presented multi-scale FE models, an alternative process variant is analysed in this work, where advantageous compressive residual stresses can be generated instead of tensile residual stresses through tailored cooling from the forming heat in the specimen. The tailored cooling is achieved by partially exposing the specimen to a water-air spray. In this way, the local plastification can be influenced by inhomogeneous strains due to thermal and transformation-induced effects in order to customise the resulting residual stress distribution. The scientific challenge of this work is to generate different residual stresses in the surface of the specimen without changing the geometrical and microstructural properties. It is demonstrated that influencing the residual stresses and even reversing the stress sign is possible using smart process control during cooling., Ziel dieser Arbeit ist die Einstellung eines vorteilhaften Druckeigenspannungsprofils in warmumgeformten Bauteilen durch intelligente Prozessführung mit angepasster Abkühlung aus der Schmiedewärme. Die Machbarkeit und das Potenzial werden an einem Warmumformprozess, bei dem zylindrische Proben mit exzentrischer Bohrung bei 1000 °C umgeformt und anschließend aus der Schmiedewärme im Wasser abgekühlt werden, aufgezeigt. Vorige Arbeiten zeigen, dass sich Zugeigenspannungen in den derartig umgeformten Proben aus dem Material 1.3505 einstellen. Mittels der vorgestellten mehrskaligen FE-Modelle, wird in dieser Arbeit eine alternative Prozessvariante analysiert, mit der vorteilhafte Druckeigenspannungen anstelle von Zugeigenspannungen durch eine angepasste Abkühlung aus der Umformwärme in den Proben erzeugt werden können. Die angepasste Kühlung wird durch eine partielle Beaufschlagung der Proben mit einem Wasser-Luft-Spray erreicht. Auf diese Weise kann die lokale Plastifizierung durch inhomogene Verzerrungen aufgrund thermischer und umwandlungsinduzierter Effekte beeinflusst werden, um letztlich das Eigenspannungsprofil individuell zu gestalten. Die wissenschaftliche Herausforderung dieser Arbeit besteht darin, unterschiedliche Eigenspannungen in der Oberfläche der Proben zu erzeugen, während die geometrischen und mikrostrukturellen Eigenschaften gleichbleiben. Es wird nachgewiesen, dass eine Beeinflussung der Eigenspannungen und sogar die Umkehr des Spannungsvorzeichens allein durch eine geschickte Prozessführung beim Abkühlen möglich ist.

Background: As adults with congenital heart disease (ACHD) are getting older, acquired comorbidities play an important role in morbidity and mortality. Data regarding their prevalence in ACHD that are representative on a population level are not available. Methods: The German National Register for Congenital Heart Defects was screened for ACHD. Underlying congenital heart disease (CHD), patient demographics, previous interventional/surgical interventions, and comorbidities were retrieved. Patients <40 years of age were compared to those ≥40 years. Results: A total of 4673 patients (mean age 33.6 ± 10.7 years, female 47.7%) was included. At least one comorbidity was present in 2882 patients (61.7%) altogether, and in 56.8% of patients below vs. 77.7% of patients over 40 years of age (p < 0.001). Number of comorbidities was higher in patients ≥40 years (2.1 ± 2.1) than in patients <40 years (1.2 ± 1.5, p < 0.001). On multivariable regression analysis, age and CHD complexity were significantly associated with the presence and number of comorbidities. Conclusions: At least one acquired comorbidity is present in approximately two-thirds of ACHD. Age and complexity of the CHD are significantly associated with the presence of comorbidities. These findings highlight the importance of addressing comorbidities in ACHD care to achieve optimal long-term outcomes.

Aims The post-approval MELODY Registry aimed to obtain multicentre registry data after transcatheter pulmonary valve implantation (TPVI) with the Melody (TM) valve (Medtronic plc.) in a large-scale cohort of patients with congenital heart disease (CHD). Methods and results Retrospective analysis of multicentre registry data after TPVI with the Melody (TM) valve. Eight hundred and forty-five patients (mean age: 21.0 +/- 11.1 years) underwent TPVI in 42 centres between December 2006 and September 2013 and were followed-up for a median of 5.9 years (range: 0-11.0 years). The composite endpoint of TPVI-related events during follow-up (i.e. death, reoperation, or reintervention >48 h after TPVI) showed an incidence rate of 4.2% per person per year [95% confidence interval (CI) 3.7-4.9]. Transcatheter pulmonary valve implantation infective endocarditis (I.E.) showed an incidence rate of 2.3% per person per year (95% CI 1.9-2.8) and resulted in significant morbidity and in nine deaths. In multivariable Cox proportional hazard models, the invasively measured residual right ventricle (RV)-to-pulmonary artery (PA) pressure gradient (per 5 mmHg) was associated with the risk of the composite endpoint (adjusted hazard ratio: 1.21, 95% CI 1.12-1.30; P<0.0001) and the risk of TPVI I.E. (adjusted hazard ratio: 1.19, 95% CI 1.07-1.32; P=0.002). Major procedural complications (death, surgical, or interventional treatment requirement) occurred in 0.5%, 1.2%, and 2.0%, respectively. Acutely, the RV-to-PA pressure gradient and the percentage of patients with pulmonary regurgitation grade >2 improved significantly from 36 [interquartile range (IQR) 24-47] to 12 (IQR 7-17) mmHg and 47 to 1%, respectively (P < 0.001 for each). Conclusion The post-approval MELODY Registry confirms the efficacy of TPVI with the Melody (TM) valve in a large-scale cohort of CHD patients. The residual invasively measured RV-to-PA pressure gradient may serve as a target for further improvement in the composite e

Myocarditis represents an important cause for acute heart failure. MYKKE, a prospective multicenter registry of pediatric patients with myocarditis, aims to gain knowledge on courses, diagnostics, and therapy of pediatric myocarditis. The role of mechanical circulatory support (MCS) in children with severe heart failure and myocarditis is unclear. The aim of this study was to determine characteristics and outcome of patients with severe heart failure requiring MCS and/or heart transplantation. The MYKKE cohort between September 2013 and 2016 was analyzed. A total of 195 patients were prospectively enrolled by 17 German hospitals. Twenty-eight patients (14%) received MCS (median 1.5 years), more frequently in the youngest age group (0-2 years) than in the older groups (P < 0.001; 2-12 and 13-18 years). In the MCS group, 50% received a VAD, 36% ECMO, and 14% both, with a survival rate of 79%. The weaning rate was 43% (12/28). Nine (32%) patients were transplanted, one had ongoing support, and six (21%) died. Histology was positive for myocarditis in 63% of the MCS group. Patients within the whole cohort with age <2 years and/or ejection fraction <30% had a significantly worse survival with high risk for MCS, transplantation, and death (P < 0.001). Myocarditis represents a life-threatening disease with an overall mortality of 4.6% in this cohort. The fulminant form more often affected the youngest, leading to significantly higher rate of MCS, transplantation, and mortality. MCS represents an important and life-saving therapeutic option in children with myocarditis with a weaning rate of 43%.

Residual stresses in components are a central issue in almost every manufacturing process, as they influence the performance of the final part. Regarding hot forming processes, there is a great potential for defining a targeted residual stress state, as many adjustment parameters, such as deformation state or temperature profile, are available that influence residual stresses. To ensure appropriate numerical modeling of residual stresses in hot forming processes, comprehensive material characterization and suitable multiscale Finite Element (FE) simulations are required. In this paper, experimental and numerical investigations of thermo-mechanically processed steel alloy 1.3505 (DIN 100Cr6) are presented that serve as a basis for further optimization of numerically modeled residual stresses. For this purpose, cylindrical upsetting tests at high temperature with subsequently cooling of the parts in the media air or water are carried out. Additionally, the process is simulated on the macroscale and compared to the results based on the experimental investigations. Therefore, the experimentally processed specimens are examined regarding the resulting microstructure, distortions, and residual stresses. For the investigation on a smaller scale, a numerical model is set up based on the state-data of the macroscopic simulation and experiments, simulating the transformation of the microstructure using phase-field theory and FE analysis on micro- and meso-scopic level.

In current research, more and more attention is paid to the understanding of residual stress states as well as the application of targeted residual stresses to extend e.g. life time or stiffness of a part. In course of that, the numerical simulation and analysis of the forming process of components, which goes along with the evolution of residual stresses, play an important role. In this contribution, we focus on the residual stresses arising from the austenite-to-martensite transformation at microscopic and mesoscopic level of a Cr-alloyed steel. A combination of a Multi-Phase-Field model and a two-scale Finite Element simulation is utilized for numerical analysis. A first microscopic simulation considers the lattice change, such that the results can be homogenized and applied on the mesoscale. Based on this result, a polycrystal consisting of a certain number of austenitic grains is built and the phase transformation from austenite to martensite is described with respect to the mesoscale. Afterwards, in a two-scale Finite Element simulation the plastic effects are considered and resulting residual stress states are computed.

Item does not contain fulltext, OBJECTIVES: This study examines the outcome and procedural outcomes of percutaneous stent angioplasty for aortic coarctation in patients with Turner syndrome (TS). BACKGROUND: TS occurs in 1 in 2,500 live-born females and is associated with aortic coarctation. METHODS: In this multicenter, retrospective cohort study, all patients with TS and a coarctation of the aorta, treated with percutaneous stent implantation were included. The procedural strategies were dictated by local protocols. Adverse events at short- and long-term follow-up and qualitative parameters concerning the stent implantation were assessed. RESULTS: In the largest study to date of TS patients receiving aortic stents, a total of 19 patients from 10 centers were included. Twelve patients were treated for native and 7 for recurrent coarctation. Age at intervention was 16.9 (7-60) years (median; min-max). The coarctation diameter increased significantly from 8.0 mm (2-12) pre-intervention to 15.0 mm (10-19) post-intervention (P < 0.001). Three (15.8%) adverse events occurred within 30 days of the procedure, including two dissections despite the use of covered stents, one resulting in death. At long-term follow-up (6.5 years, min-max: 1-16), two additional deaths occurred not known to be stent-related. CONCLUSIONS: Though percutaneous treatment of aortic coarctation in TS patients is effective, it is associated with serious morbidity and mortality. These risks suggest that alternative treatment options should be carefully weighed against percutaneous stenting strategies. (c) 2016 Wiley Periodicals, Inc.

BACKGROUND: Systemic right ventricular (RV) dysfunction and sudden cardiac death remain problematic late after Mustard operation for transposition of the great arteries. The exact mechanism for that relationship is likely to be multifactorial including myocardial fibrosis. Doppler echocardiography gives further insights into the role of fibrosis shown by late gadolinium enhancement (LGE) cardiovascular magnetic resonance (CMR) in late morbidity. METHODS AND RESULTS: Twenty-two consecutive patients, mean age 28±8years, were studied with 2D echocardiography, and also assessed by LGE CMR. The presence of LGE in 13/22 patients (59%) was related to delayed septal shortening and lengthening (P=0.002 &P=0.049), prolonged systemic RV isovolumic contraction time (P=0.024) and reduced systemic RV free wall and septal excursion (P=0.027 &P=0.005). The systemic RV total isovolumic time was prolonged but not related to extent of LGE. LGE extent was related to markers of electromechanical delay and dyssynchrony (delayed onset of RV free wall shortening and lengthening; r=0.73 &P=0.004 and r=0.62 &P=0.041, respectively, and QRS duration r=0.68, P<0.01) and was inversely related to systolic RV free wall shortening velocity (r=-0.59 &P=0.042). The presence of LGE was also related to lower exercise capacity, ≥mild tricuspid regurgitation and more arrhythmia (P=0.008, P=0.014 and P=0.040). RV free wall excursion and systolic tissue Doppler velocity were related to CMR derived RV ejection fraction (r=0.51, P=0.015, and r=0.77, P=<0.001, respectively). CONCLUSION: Post Mustard repair, myocardial fibrosis is related to dyssynchrony, RV long axis dysfunction and tricuspid regurgitation. Echocardiographic measurements of systemic RV function can be confidently used in serial follow-up following Mustard operation.