Stress-Echokardiografie

2020 ◽  
Vol 9 (01) ◽  
pp. 50-59
Author(s):  
Andreas Hagendorff ◽  
Michael Metze ◽  
Martin Neef ◽  
Daniel Jurisch ◽  
Stephan Stöbe
Keyword(s):  
Die Stress ◽  
Kardiologische Diagnostik

ZusammenfassungDie Stress-Echokardiografie ist wegen der verschiedenen Modalitäten (dynamische und pharmakologische Stress-Echokardiografie) eine komplexe Thematik. Bei der Auswahl der besten diagnostischen Möglichkeit spielen vor allem Schallbarkeit und Komorbiditäten des Patienten/der Patientin eine wesentliche Rolle. Für die Durchführung einer Stress-Echokardiografie müssen, neben einer adäquaten Ultraschall-Geräteausstattung, die technischen und personellen Anforderungen zur Behandlung von Akutkomplikationen bis hin zur Reanimation berücksichtigt werden. Der Untersucher muss in allen Bereichen der transthorakalen Echokardiografie ausgebildet sein und ein ausreichendes Training im Bereich der Stress-Echokardiografie absolviert haben. Dies umfasst Kenntnisse über Indikationen, Kontraindikationen und Abbruchkriterien einer Stress-Echokardiografie, die Bildakquisition unter erschwerten Bedingungen sowie die Optimierung und Auswertung des akquirierten Bildmaterials. Hauptindikationen stellen die Ischämie- und Vitalitätsdiagnostik dar, gefolgt von Indikationen zur spezifischen Abklärung von Kardiomyopathien und Herzklappenerkrankungen. Grundvoraussetzung für eine zielführende kardiologische Diagnostik stellt dabei die Planung der zu verwendenden Stressprotokolle in Abhängigkeit der jeweiligen klinischen Fragestellung dar. Die diagnostische und prognostische Aussagekraft der Stress-Echokardiografie ist hoch, wobei gerade in der Stress-Echokardiografie hohe Anforderungen an die praktischen Fähigkeiten und klinische Erfahrung des Untersuchers gestellt werden.

Aktueller Stellenwert der Kardio-MRT in Diagnostik und Therapie

2021 ◽  
Vol 146 (07) ◽  
pp. 461-465
Author(s):  
Julia M. Vietheer ◽  
Christian W. Hamm ◽  
Andreas Rolf
Keyword(s):  
Late Gadolinium Enhancement ◽  
T2 Mapping ◽  
Strain Imaging ◽  
Gadolinium Enhancement ◽  
Quantitative Parameter ◽  
Diagnostik Und Therapie ◽  
Die Stress

Quantifizierung der links- und rechtsventrikulären Funktion Strain Imaging erweitert die klassische Volumetrie der MRT um einen sehr subtilen globalen und regionalen Funktionsparameter. Strain detektiert sehr frühe Funktionseinbußen beider Ventrikel, die visuell noch nicht erkennbar sind. Insbesondere der longitudinale Strain ist bei ischämischen und nichtischämischen Erkrankungen frühzeitig reduziert. Strain hat über die EF hinaus zusätzliche prognostische Bedeutung. Gewebecharakterisierung T1- und T2-Mapping erweitern die klassische Gewebecharakterisierung mit Late Gadolinium Enhancement (LGE) um sehr subtile quantitative Parameter, die diffuse Fibrose (T1) und Ödem (T1 und T2) widerspiegeln. Ischämiediagnostik Die Perfusions-MRT unter Vasodilatatorstress ist das genaueste Verfahren zur Ischämiediagnostik. Die MR-INFORM-Studie zeigt, dass mithilfe der Stress-MRT fast die Hälfte der Katheteruntersuchungen in einem Kollektiv mit hoher Prätestwahrscheinlichkeit vermieden werden kann. Dabei ist die Stress-MRT der FFR-basierten Strategie nicht unterlegen und genauso sicher.

scholarly journals Generalized optimizations of two-stage forging of micro/meso copper fastener

2018 ◽  
Vol 185 ◽  
pp. 00002
Author(s):  
Shih-Hsien Lin ◽  
Un-Chin Chai ◽  
Gow-Yi Tzou ◽  
Dyi-Cheng Chen
Keyword(s):  
Simulation Analysis ◽  
Effective Strain ◽  
Cold Forging ◽  
Two Stage ◽  
Forming Simulation ◽  
Multi Stage ◽  
Element Simulation ◽  
Die Stress ◽  
Stress Optimization ◽  
Forging Force

Three are generalized simulation optimizations considering the forging force, the die stress, and the dual-goals in two-stage forging of micro/meso copper fastener. Constant shear friction between the dies and workpiece is assumed to perform multi-stage cold forging forming simulation analysis, and the Taguchi method with the finite element simulation has been used for mold-and-dies parameters design simulation optimizations considering the forging force, die stress, and dual-goals. The die stress optimization is used to explore the effects on effective stress, effective strain, velocity field, die stress, forging force, and shape of product. The influence rank to forging process of micro/meso copper fastener for three optimizations can be determined, and the optimal parameters assembly consider die stress can be obtained in this study. It is noted that the punch design innovation can reduce the forging force and die stress.

scholarly journals Investigation on Die Crack in a Stacked Die Package Using Finite Element Analysis

2021 ◽  
pp. 83-91
Author(s):  
Jefferson Talledo
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Coefficient Of Thermal Expansion ◽  
Crack Problem ◽  
Element Analysis ◽  
Robust Solution ◽  
Die Attach ◽  
Die Stress ◽  
Cte Mismatch ◽  
Semiconductor Packages

Die crack is one of the problems in stacked die semiconductor packages. As silicon dies become thinner in such packages due to miniaturization requirement, the tendency to have die crack increases. This study presents the investigation done on a die crack issue in a stacked die package using finite element analysis (FEA). The die stress induced during the package assembly processes from die attach to package strip reflow was analyzed and compared with the actual die crack failure in terms of the location of maximum die stress at unit level as well as strip level. Stresses in the die due to coefficient of thermal expansion (CTE) mismatch of the package component materials and mechanical bending of the package in strip format were taken into consideration. Comparison of the die stress with actual die crack pointed to strip bending as the cause of the problem and not CTE mismatch. It was found that the die crack was not due to the thermal processes involved during package assembly. This study showed that analyzing die stress using FEA could help identify the root cause of a die crack problem during the stacked die package assembly and manufacturing as crack occurs at locations of maximum stress. The die crack mechanism can also be understood through FEA simulation and such understanding is very important in coming up with robust solution.

scholarly journals Forming parameters optimizations with drawing force and die stress in wire rod drawing using rotating die under Coulomb friction

2018 ◽  
Vol 185 ◽  
pp. 00025
Author(s):  
Ing-Kiat Tiong ◽  
Un-Chin Chai ◽  
Gow-Yi Tzou
Keyword(s):  
Taguchi Method ◽  
Coulomb Friction ◽  
Effective Strain ◽  
Fem Simulation ◽  
Frictional Coefficient ◽  
Simulation Software ◽  
Drawing Force ◽  
Wire Rod ◽  
Forming Parameters ◽  
Die Stress

An optimization research is performed on the related forming parameters of wire rod drawing through a rotating die under Coulomb friction. The optimization research is conducted through finite element method (FEM) simulation combined with Taguchi method. There are two drawing characteristic optimizations have been carried out. They are the optimizations with drawing force and die stress. The forming parameters considered in this study are half die angle, frictional coefficient, die fillet, and rotating angular velocity of the rotating die. The same procedure is carried out in both optimizations. The geometrical models of the wire rod, top die and rotating die are constructed firstly in SolidWorks and imported into the FEM simulation software named DEFORM 3D. With the aid of Taguchi method, the simulation experiments are carried out. The results such as drawing force, die stress, and the corresponding signal-to-noise (S/N) ratio are obtained and compared. The influence rank of the forming parameters and the optimal combination of parameters are obtained through the response table for both optimizations. The results such as effective stress, effective strain, velocity field, drawing force, and die stress are studied. The results show that the minimizations of drawing force and die stress are successfully achieved.

Piezoresistive Stress Sensors for Structural Analysis of Electronic Packages

1991 ◽  
Vol 113 (3) ◽  
pp. 203-215 ◽  
Author(s):  
D. A. Bittle ◽  
J. C. Suhling ◽  
R. E. Beaty ◽  
R. C. Jaeger ◽  
R. W. Johnson
Keyword(s):  
Integrated Circuit ◽  
Structural Reliability ◽  
Lattice Structure ◽  
Three Dimensional ◽  
Electronic Packages ◽  
Cubic Symmetry ◽  
Piezoresistive Sensors ◽  
Stress Sensors ◽  
Die Stress ◽  
Test Chips

Structural reliability of electronic packages has become an increasing concern for a variety of reasons including the advent of higher integrated circuit densities, power density levels, and operating temperatures. A powerful method for experimental evaluation of die stress distributions is the use of test chips incorporating integral piezoresistive sensors. In this paper, the theory of conduction in piezoresistive materials is reviewed and the basic equations applicable to the design of stress sensors on test chips are presented. General expressions are obtained for the stress-induced resistance changes which occur in arbitrarily oriented one-dimensional filamentary conductors fabricated out of crystals with cubic symmetry and diamond lattice structure. These relations are then applied to obtain basic results for stressed in-plane resistors fabricated into the surface of (100) and (111) oriented silicon wafers. Sensor rosettes developed by previous researchers for each of these wafer orientations are reviewed and more powerful rosettes are presented along with the equations needed for their successful application. In particular, a new sensor rosette fabricated on (111) silicon is presented which can measure the complete three-dimensional stress state at points on the surface of a die

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