Stress testing and non-invasive coronary angiography in patients with suspected coronary artery disease: time for a new paradigm

Diagnosis and management of coronary artery disease represents major challenges to our health care system, affecting millions of patients each year. Until recently, the diagnosis of coronary artery disease was possible only through cardiac catheterization and invasive coronary angiography. To avoid the risks of an invasive procedure, stress testing is often employed for an initial assessment of patients with suspected coronary artery disease, serving as a gatekeeper for cardiac catheterization. With the emergence of non-invasive coronary angiography, the question arises if such a strategy is still sensible, particularly, in view of only a modest agreement between stress testing results and the presence of coronary artery disease established by cardiac catheterization. Much data in support of the diagnostic accuracy and prognostic value of non-invasive coronary angiography by computed tomography have emerged within the last few years. These data challenge the role of stress testing as the initial imaging modality in patients with suspected coronary artery disease. This article reviews the clinical utility, limitations, as well as the hazards of stress testing compared with non-invasive coronary artery imaging by computed tomography. Finally, the implications of this review are discussed in relation to clinical practice

Blue diode lasers: Evaluation of capillary and melt pool dynamics

In the recent years, laser beam welding has become an established joining process, especially for components in the electrical powertrain (copper applications). However, laser beam welding of copper is generally considered to be difficult, particularly due to its high heat conductivity and due to its low absorptivity using laser sources with a wavelength of 1 μm. The resulting welds show numerous weld defects, such as pores and spatters. Using “blue” lasers with a wavelength of 450 nm promises a smoother welding process with less spatters. Therefore, a blue diode laser with increased absorptivity in copper materials was developed by Laserline and used for welding copper. In this contribution, the results of welding copper using blue lasers with respect to the penetration depth and the resulting weld quality are discussed. In addition, investigations by Bosch at the electron-synchrotron DESY with a blue diode laser enabled us to have a look into the material during welding. Consequently, melt pool dynamics and capillary dynamics were analyzed with respect to the formation of weld defects and will be discussed as well. Furthermore, it is demonstrated that it can be beneficial to use a so-called spot-in-spot beam shaping tool to further improve the melt pool dynamics and, therefore, the resulting weld quality