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Berlin, Germany

Romero D.,Aragon Institute of Engineering Research | Ringborn M.,Lund University | Ringborn M.,Thorax Center | Laguna P.,Aragon Institute of Engineering Research | And 2 more authors.
IEEE Transactions on Biomedical Engineering | Year: 2011

Diagnosis and risk stratification of patients with acute coronary syndromes can be improved by adding information from the depolarization phase (QRS complex) to the conventionally used ST-T segment changes. In this study, ischemia-induced changes in the main three slopes of the QRS complex, upward (XUS) and downward (XDS) slopes of the R wave as well as the upward (ITS) slope of the terminal S wave, were evaluated as to represent a robust measure of pathological changes within the depolarization phase. From ECG recordings both in a resting state (control recordings) and during percutaneous coronary intervention (PCI)-induced transmural ischemia, we developed a method for quantification of IUS, IDS, and ITS that incorporates dynamic ECG normalization so as to improve the sensitivity in the detection of ischemia-induced changes. The same method was also applied on leads obtained by projection of QRS loops onto their dominant directions. We show that IUS, IDS, and ITS present high stability in the resting state, thus providing a stable reference for ischemia characterization. Maximum relative factors of change (RI) during PCI were found in leads derived from the QRS loop, reaching 10.5 and 13.7 times their normal variations in the control for IUS and IDS, respectively. For standard leads, the relative factors of change were 6.01 and 9.31. The ITS index presented a similar behavior to that of IDS. The timing for the occurrence of significant changes in IUS and IDS varied with lead, ranging from 30 s to 2 min after initiation of coronary occlusion. In the present ischemia model, relative IDS changes were smaller than ST changes in most leads, however with only modest correlation between the two indices, suggesting they present different information about the ischemic process. We conclude that QRS slopes offer a robust tool for evaluating depolarization changes during myocardial ischemia. © 2011 IEEE. Source


Iqbal J.,University of Sheffield | Serruys P.W.,Thorax Center | Taggart D.P.,University of Oxford
Nature Reviews Cardiology | Year: 2013

Patients with major or symptomatic coronary artery disease (CAD) commonly undergo revascularization-either with CABG surgery, which has been the mainstay of revascularization for more than half a century, or with percutaneous coronary intervention (PCI), which has become the more-commonly used strategy in the past decade. PCI has been tested in more randomized clinical trials than any other procedure in contemporary practice. In general, PCI is the preferred option for treating patients with simple coronary artery lesions and CABG surgery remains the standard of care for patients with complex CAD. Technical advancements in PCI and CABG surgery make comparisons of historical data for these strategies difficult. In this Review, we evaluate the evidence-based use of PCI and CABG surgery in treating patients with multivessel and unprotected left main stem disease and for specific patient groups, including those with diabetes mellitus, chronic heart failure, or chronic kidney disease. Finally, we highlight the available tools to aid decision-making, including clinical guidelines, risk scoring systems, and the role of the 'heart team'. © 2013 Macmillan Publishers Limited. All rights reserved. Source


Salameh A.,University of Leipzig | Dhein S.,University of Leipzig | Fleischmann B.,University of Bonn | Grohe C.,University of Bonn | And 4 more authors.
Journal of Physiology and Pharmacology | Year: 2010

The aim of this study was to investigate whether the L-type calcium current (ICa.L) may be altered in aged hearts and whether the classical calcium antagonist verapamil may exhibit altered pharmacological profile in aged hearts. We examined male New Zealand rabbits aged either 6 months or 26 months. To examine ICa.L whole-cell patch-clamp technique was performed on isolated cells. Moreover, activation-recovery intervals (ARI) of isolated hearts (Langendorff method) were assessed using an epicardial 256 channel mapping system. We found that the ICa.L density, normalised to the cell volume was significantly reduced (p<0.001). Maximum conductance was also significantly decreased (p=0.01) and steady state inactivation was shifted to more positive potentials in aged hearts (p<0.001). A slightly reduced effect of β-adrenergic modulation of the ICa.L in aged hearts, and a significantly reduced effect of carbachol on isoprenaline-stimulated ICa.L in aged hearts was observed. L-type α1c subunit, SERCA2-ATPase and the Na+/Ca2+-exchanger expression were neither significantly different in atrial and ventricular tissues nor between young and old animals. Using the mapping system, isolated hearts were exposed to verapamil (0.005, 0.01, 0.02, 0.05 μM/L). While verapamil did not affect ARI in young hearts, in aged hearts ARI was concentration-dependently reduced and the negative inotropic effect of verapamil was significantly attenuated in aged hearts (p<0.05). From these results we conclude that there are distinct alterations in the electrophysiology of ICa.L (reduced maximum conductance, a shift of the steady state inactivation) in the aged heart which may influence the response to verapamil. Source


Jansen K.,Thorax Center | Jansen K.,Interuniversity Cardiology Institute of the Netherlands Netherlands Heart Institute | Van Der Steen A.F.W.,Thorax Center | Van Der Steen A.F.W.,Interuniversity Cardiology Institute of the Netherlands Netherlands Heart Institute | And 11 more authors.
Journal of Biomedical Optics | Year: 2014

The natural history of atherosclerosis is marked by changes in the lipid biochemistry in the diseased arterial wall. As lesions become more vulnerable, different cholesterol species accumulate in the plaque. Understanding unstable atherosclerosis as a pharmacological and interventional therapeutic target requires chemically specific imaging of disease foci. In this study, we aim to image atherosclerotic plaque lipids and other vessel wall constituents with spectroscopic intravascular photoacoustics (sIVPA). sIVPA imaging can identify lipids in human coronary atherosclerotic plaque by relying on contrast in the near-infrared absorption spectra of the arterial wall components. Using reference spectra acquired on pure compounds, we analyzed sIVPA data from human coronary plaques ex vivo, to image plaque composition in terms of cholesterol and cholesterol ester content. In addition, we visualized the deeper lying connective tissue layers of the adventitia, as well as the fatty acid containing adipose cells in the peri-adventitial tissue. We performed simultaneous coregistered IVUS imaging to obtain complementary morphological information. Results were corroborated by histopathology. sIVPA imaging can distinguish the most prevalent lipid components of human atherosclerotic plaques and also visualize the connective tissue layers of the adventitia and the fatty acid containing adipose cells in the peri-adventitial tissue. © 2014 Society of Photo-Optical Instrumentation Engineers. Source


Vos H.J.,Thorax Center | Goertz D.E.,Thorax Center | Goertz D.E.,University of Toronto | De Jong N.,Thorax Center
Journal of the Acoustical Society of America | Year: 2010

High-frequency (>10 MHz) ultrasound is used in, e.g., small animal imaging or intravascular applications. Currently available ultrasound contrast agents (UCAs) have a suboptimal response for high frequencies. This study therefore investigates the nonlinear propagation effects in a high-frequency ultrasound field (25 MHz) and its use for standard UCA and diagnostic frequencies (1-3 MHz). Nonlinear mixing of two high-frequency carrier waves produces a low-frequency wave, known as the self-demodulation or parametric array effect. Hydrophone experiments showed that the self-demodulated field of a focused 25 MHz transducer (850 kPa source pressure) has an amplitude of 45 kPa at 1.5 MHz in water. Such pressure level is sufficient for UCA excitation. Experimental values are confirmed by numerical simulations using the Khokhlov-Zabolotskaya-Kuznetsov equation on a spatially convergent grid. © 2010 Acoustical Society of America. Source

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