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  • KIT - Willkommen am Institut für Biomedizinische Technik
    uns auf dem Campus IBT Intern Stellenangebote Institutsleitung Prof Dr rer nat Olaf Dössel Postanschrift Kaiserstr 12 76128 Karlsruhe Besucheradresse Lieferanschrift Gebäude 30 33 Fritz Haber Weg 1 76131 Karlsruhe Tel 49 721 608 42650 Fax 49 721 608 42789 E Mail info Ump0 ibt kit edu Aktuelles Seminar über wissenschaftliche Arbeiten in der Biomedizinischen Technik Soweit nicht anderweitig angegeben finden die Vorträge im Seminarraum des Instituts für Biomedizinische Technik

    Original URL path: http://www.ibt.kit.edu/ (2015-05-18)
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  • KIT - Willkommen am Institut für Biomedizinische Technik
    uns auf dem Campus IBT Intern Stellenangebote Institutsleitung Prof Dr rer nat Olaf Dössel Postanschrift Kaiserstr 12 76128 Karlsruhe Besucheradresse Lieferanschrift Gebäude 30 33 Fritz Haber Weg 1 76131 Karlsruhe Tel 49 721 608 42650 Fax 49 721 608 42789 E Mail info Apa3 ibt kit edu Aktuelles Seminar über wissenschaftliche Arbeiten in der Biomedizinischen Technik Soweit nicht anderweitig angegeben finden die Vorträge im Seminarraum des Instituts für Biomedizinische Technik

    Original URL path: http://www.ibt.kit.edu/index.php (2015-05-18)
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  • KIT - Welcome to Institute of Biomedical Engineering
    Lectures Bachelor and master theses Examinations Hard Software WWW Service How to find us on campus IBT Intern Jobs Institute Administration Prof Dr rer nat Olaf Dössel Postal address Kaiserstr 12 76128 Karlsruhe Visitor Delivery address Building 30 33 Fritz Haber Weg 1 76131 Karlsruhe Fon 49 721 608 42650 Fax 49 721 608 42789 E Mail info Fzy9 ibt kit edu NEWS RSS Feed last change 2014 07 31

    Original URL path: http://www.ibt.kit.edu/english/index.php (2015-05-18)
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  • KIT - Institut für Biomedizinische Technik
    pädagogische wissenschaftliche oder private Zwecke ist unter Angabe der Quelle gestattet sofern nicht anders an der entsprechenden Stelle ausdrücklich angegeben Eine Verwendung im gewerblichen Bereich bedarf der Genehmigung durch das Karlsruher Institut für Technologie Ansprechpartner ist die Dienstleistungseinheit Presse Kommunikation und Marketing Haftung Diese Internetseiten dienen lediglich der Information Ihr Inhalt wurde mit gebührender Sorgfalt zusammengestellt Das Karlsruher Institut für Technologie übernimmt aber keine Garantie weder ausdrücklich noch implizit für die Art oder Richtigkeit des dargebotenen Materials und übernimmt keine Haftung einschließlich Haftung für indirekten Verlust oder Gewinn oder Umsatzverluste bezüglich des Materials bzw der Nutzung dieses Materials Sollten Inhalte von Web Seiten des Karlsruher Instituts für Technologie gegen geltende Rechtsvorschriften verstoßen dann bitten wir um umgehende Benachrichtigung Wir werden die Seite oder den betreffenden Inhalt dann schnellstmöglich entfernen Verweise auf externe Web Seiten Die Web Seiten des Karlsruher Instituts für Technologie enthalten Verweise Links zu Informationsangeboten auf Servern die nicht der Kontrolle und Verantwortlichkeit des Karlsruher Instituts für Technologies unterliegen Das Karlsruher Institut für Technologie übernimmt keine Verantwortung und keine Garantie für diese Informationen und billigt oder unterstützt diese auch nicht inhaltlich Datenschutz und IT Sicherheit Das Karlsruher Institut für Technologie verpflichtet sich die Privatsphäre aller Personen zu schützen die unsere Site nutzen und die uns überlassenen personenbezogenen Daten vertraulich zu behandeln Die Daten werden ausschließlich für die jeweils angegebenen Zwecke verwendet und nicht an Dritte weitergegeben Ihre Daten werden gelöscht sobald sie dem angegebenen Zweck gedient haben Verschlüsselungstechniken werden auf unseren Internetseiten derzeit nur zur Authentifizierung eingesetzt Sie müssen also damit rechnen dass Ihre Angaben auf dem Wege zu uns Unbefugten zur Kenntnis kommen Wenn Sie dies vermeiden wollen so wenden Sie sich bitte auf anderem Wege an die jeweils angegebene Kontaktstelle oder Kontaktperson Zur Aufrechterhaltung Ihrer Sitzung kann es u U notwendig sein ein Cookie zu setzen

    Original URL path: http://www.ibt.kit.edu/2635.php (2015-05-18)
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  • KIT - Institut für Biomedizinische Technik
    Home english Impressum Sitemap KIT Institut für Biomedizinische Technik letzte Änderung 20 03 2015 KIT Universität des Landes Baden Württemberg und nationales Forschungszentrum in der Helmholtz Gemeinschaft

    Original URL path: http://www.ibt.kit.edu/2636.php (2015-05-18)
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  • KIT - Unser Profil
    medizinischen Partner sind an folgenden Kliniken Universitätsklinik Heidelberg Prof Dr med Hugo A Katus Prof Dr rer nat David Hassel PD Dr med Eberhard Scholz Universitätsklinik Mannheim PD Dr med Rainer Schimpf Univ Prof Dr med Martin Borggrefe Prof Dr med Theano Papavassiliu Städtisches Klinikum Karlsruhe Prof Dr med Claus Schmitt Dr med Armin Luik King s College London Wir haben weiterhin gute wissenschaftliche Kontakte zu Dana Brooks Boston Oscar

    Original URL path: http://www.ibt.kit.edu/profil.php (2015-05-18)
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  • KIT - Forschung
    neue Therapiekonzepte erprobt werden können Unsere Forschungsthemen liegen in den Bereichen Computermodelle vom Herzen Abbildung bioelektrischer Quellen auf dem Herzen Biosignalverarbeitung von EKG Daten Berechnung von elektrischen und magnetischen Feldern im Körper Projekte Medizinische Messtechnik Digitale Signalverarbeitung Titel Ansprechpartner Simultaneous fluorescence optical and electrical characterization of atrial tissue Stefan Pollnow Olaf Dössel Analyzing the intracardiac measurements for understanding of cardiac arrhythmia based on pacing sequences Bhawna Verma Olaf Dössel Ultra Wideband Based Imaging Technology for Stroke Detection Jochen Schmid Olaf Dössel Analysis of rhythmical and morphological properties of the ECG to detect cardiac abnormalities Gustavo Lenis Olaf Dössel Intracardial ECG Signal Processing Mapping of endocardial activation patterns Tobias Oesterlein Olaf Dössel Multivariate Zeitreihenanalyse im Oberflächen EKG Gustavo Lenis Olaf Dössel Modelle vom Körper Titel Ansprechpartner MEET Man Projekt Gunnar Seemann Olaf Dössel Herzmodellierung Titel Ansprechpartner In silico Assessment of Arrhythmogenic Potential of Atrial Ablation Patterns Axel Loewe Gunnar Seemann Olaf Dössel In silico Investigation of Electrophysiological Atrial Fibrillation Mechanisms Axel Loewe Gunnar Seemann Olaf Dössel Software development for cardiac excitation conduction and tension development Gunnar Seemann Olaf Dössel Electrophysiological assessment of the myocyte fibroblast interactions in the heart Gunnar Seemann Olaf Dössel Personalizing Atrial Simulations Electrograms Cell Models Torso Conductivities Gunnar Seemann Olaf Dössel Simulation and Analysis of Intracardiac Electrograms Gunnar Seemann Olaf Dössel euHeart Angelegenheiten des Herzens Martin Krüger Walther Schulze Gunnar Seemann Olaf Dössel Electrophysiological Investigation of Familial Atrial Fibrillation Mathias Wilhelms Gunnar Seemann Olaf Dössel Modeling Acute Cardiac Ischemia Mathias Wilhelms Gunnar Seemann Olaf Dössel Patient Specific Biomechanical Modeling of the Heart Application in Dilated Cardiomyopathy Thomas Fritz Olaf Dössel Personalizing Atrial Simulations Fiber Structure Ablation Therapy ECG Martin Krüger Gunnar Seemann Olaf Dössel Modified Mass Spring System for Physically Based Deformation Modeling Thomas Fritz Olaf Dössel New Insights into the Forward Problem of Electrocardiography Gunnar Seemann

    Original URL path: http://www.ibt.kit.edu/forschung.php (2015-05-18)
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  • KIT - Veröffentlichungen & Preise
    for higher dimensional problems With the DC method we also successfully reconstructed the activation pattern and origin of a simulated extrasystole In addition the DC algorithm enables iterative adjustment of binary values ensuring robust performance J T Koivumaki G Seemann M M Maleckar and P Tavi In silico screening of the key cellular remodeling targets in chronic atrial fibrillation In PLoS Computational Biology vol 10 5 pp e1003620 2014 request PDF doi url Abstract Chronic atrial fibrillation AF is a complex disease with underlying changes in electrophysiology calcium signaling and the structure of atrial myocytes How these individual remodeling targets and their emergent interactions contribute to cell physiology in chronic AF is not well understood To approach this problem we performed in silico experiments in a computational model of the human atrial myocyte The remodeled function of cellular components was based on a broad literature review of in vitro findings in chronic AF and these were integrated into the model to define a cohort of virtual cells Simulation results indicate that while the altered function of calcium and potassium ion channels alone causes a pronounced decrease in action potential duration remodeling of intracellular calcium handling also has a substantial impact on the chronic AF phenotype We additionally found that the reduction in amplitude of the calcium transient in chronic AF as compared to normal sinus rhythm is primarily due to the remodeling of calcium channel function calcium handling and cellular geometry Finally we found that decreased electrical resistance of the membrane together with remodeled calcium handling synergistically decreased cellular excitability and the subsequent inducibility of repolarization abnormalities in the human atrial myocyte in chronic AF We conclude that the presented results highlight the complexity of both intrinsic cellular interactions and emergent properties of human atrial myocytes in chronic AF Therefore reversing remodeling for a single remodeled component does little to restore the normal sinus rhythm phenotype These findings may have important implications for developing novel therapeutic approaches for chronic AF W H W Schulze P Mackens D Potyagaylo K Rhode E Tulumen R Schimpf T Papavassiliu M Borggrefe and O Dössel Automatic camera based identification and 3 D reconstruction of electrode positions in electrocardiographic imaging In Biomedizinische Technik Biomedical Engineering vol 59 6 pp 515 528 2014 request PDF doi Abstract Electrocardiographic imaging ECG imaging is a method to depict electrophysiological processes in the heart It is an emerging technology with the potential of making the therapy of cardiac arrhythmia less invasive less expensive and more precise A major challenge for integrating the method into clinical workflow is the seamless and correct identification and localization of electrodes on the thorax and their assignment to recorded channels This work proposes a camera based system which can localize all electrode positions at once and to an accuracy of approximately 1 1 mm A system for automatic identification of individual electrodes is implemented that overcomes the need of manual annotation For this purpose a system of markers is suggested which facilitates a precise localization to subpixel accuracy and robust identification using an error correcting code The accuracy of the presented system in identifying and localizing electrodes is validated in a phantom study Its overall capability is demonstrated in a clinical scenario A Panas A Comouth H Saathoff T Leisner M Al Rawi M Simon G Seemann O Dossel S Mulhopt H R Paur S Fritsch Decker C Weiss and S Diabate Silica nanoparticles are less toxic to human lung cells when deposited at the air liquid interface compared to conventional submerged exposure In Beilstein Journal of Nanotechnology vol 5 pp 1590 1602 2014 request PDF doi Abstract BACKGROUND Investigations on adverse biological effects of nanoparticles NPs in the lung by in vitro studies are usually performed under submerged conditions where NPs are suspended in cell culture media However the behaviour of nanoparticles such as agglomeration and sedimentation in such complex suspensions is difficult to control and hence the deposited cellular dose often remains unknown Moreover the cellular responses to NPs under submerged culture conditions might differ from those observed at physiological settings at the air liquid interface RESULTS In order to avoid problems because of an altered behaviour of the nanoparticles in cell culture medium and to mimic a more realistic situation relevant for inhalation human A549 lung epithelial cells were exposed to aerosols at the air liquid interphase ALI by using the ALI deposition apparatus ALIDA The application of an electrostatic field allowed for particle deposition efficiencies that were higher by a factor of more than 20 compared to the unmodified VITROCELL deposition system We studied two different amorphous silica nanoparticles particles produced by flame synthesis and particles produced in suspension by the Stober method Aerosols with well defined particle sizes and concentrations were generated by using a commercial electrospray generator or an atomizer Only the electrospray method allowed for the generation of an aerosol containing monodisperse NPs However the deposited mass and surface dose of the particles was too low to induce cellular responses Therefore we generated the aerosol with an atomizer which supplied agglomerates and thus allowed a particle deposition with a three orders of magnitude higher mass and of surface doses on lung cells that induced significant biological effects The deposited dose was estimated and independently validated by measurements using either transmission electron microscopy or in case of labelled NPs by fluorescence analyses Surprisingly cells exposed at the ALI were less sensitive to silica NPs as evidenced by reduced cytotoxicity and inflammatory responses CONCLUSION Amorphous silica NPs induced qualitatively similar cellular responses under submerged conditions and at the ALI However submerged exposure to NPs triggers stronger effects at much lower cellular doses Hence more studies are warranted to decipher whether cells at the ALI are in general less vulnerable to NPs or specific NPs show different activities dependent on the exposure method A Loewe Y Lutz M Wilhelms D Sinnecker P Barthel E P Scholz O Dossel G Schmidt and G Seemann In silico assessment of the dynamic effects of amiodarone and dronedarone on human atrial patho electrophysiology In Europace European Pacing Arrhythmias and Cardiac Electrophysiology Journal of the Working Groups on Cardiac Pacing Arrhythmias and Cardiac Cellular Electrophysiology of the European Society of Cardiology vol 16 suppl 4 pp iv30 iv38 2014 request PDF doi Abstract AIMS The clinical efficacy in preventing the recurrence of atrial fibrillation AF is higher for amiodarone than for dronedarone Moreover pharmacotherapy with these drugs is less successful in patients with remodelled substrate induced by chronic AF cAF and patients suffering from familial AF To date the reasons for these phenomena are only incompletely understood We analyse the effects of the drugs in a computational model of atrial electrophysiology METHODS AND RESULTS The Courtemanche Ramirez Nattel model was adapted to represent cAF remodelled tissue and hERG mutations N588K and L532P The pharmacodynamics of amiodarone and dronedarone were investigated with respect to their dose and heart rate dependence by evaluating 10 descriptors of action potential morphology and conduction properties An arrhythmia score was computed based on a subset of these biomarkers and analysed regarding circadian variation of drug concentration and heart rate Action potential alternans at high frequencies was observed over the whole dronedarone concentration range at high frequencies while amiodarone caused alternans only in a narrow range The total score of dronedarone reached critical values in most of the investigated dynamic scenarios while amiodarone caused only minor score oscillations Compared with the other substrates cAF showed significantly different characteristics resulting in a lower amiodarone but higher dronedarone concentration yielding the lowest score CONCLUSION Significant differences exist in the frequency and concentration dependent effects between amiodarone and dronedarone and between different atrial substrates Our results provide possible explanations for the superior efficacy of amiodarone and may aid in the design of substrate specific pharmacotherapy for AF A Loewe W H W Schulze Y Jiang M Wilhelms A Luik O Dössel and G Seemann ECG Based Detection of Early Myocardial Ischemia in a Computational Model Impact of Additional Electrodes Optimal Placement and a New Feature for ST Deviation In BioMed Research International Article vol ID 530352 pp 1 11 2014 request PDF Abstract In case of chest pain immediate diagnosis of myocardial ischemia is required to respond with an appropriate treatment The diagnostic capability of the electrocardiogram ECG however is strongly limited for ischemic events that do not lead to ST elevation This computational study investigates the potential of different electrode setups in detecting early ischemia at 10 minutes after onset standard 3 channel and 12 lead ECG as well as body surface potential maps BSPMs Further it was assessed if an additional ECG electrode with optimized position or the right sided Wilson leads can improve sensitivity of the standard 12 lead ECG To this end a simulation study was performed for 765 different locations and sizes of ischemia in the left ventricle Improvements by adding a single subject specifically optimized electrode were similar to those of the BSPM 2 11 increased detection rate depending on the desired specificity Adding right sided Wilson leads had negligible effect Absence of ST deviation could not be related to specific locations of the ischemic region or its transmurality As alternative to the ST time integral as a feature of ST deviation the K point deviation was introduced the baseline deviation at the minimum of the ST segment envelope signal which increased 12 lead detection rate by 7 for a reasonable threshold M W Krueger W H W Schulze K Rhode R Razavi G Seemann and O Dössel Towards personalized clinical in silico modeling of atrial anatomy and electrophysiology In Medical Biological Engineering Computing vol 51 11 pp 1251 1260 2013 request PDF Abstract Computational atrial models aid the understanding of pathological mechanisms and therapeutic measures in basic research The use of biophysical models in a clinical environment requires methods to personalize the anatomy and electrophysiology EP Strategies for the automation of model generation and for evaluation are needed In this manuscript the current efforts of clinical atrial modeling in the euHeart project are summarized within the context of recent publications in this field Model based segmentation methods allow for the automatic generation of ready to simulate patient specific anatomical models EP models can be adapted to patient groups based on a priori knowledge and to the individual without significant further data acquisition ECG and intracardiac data build the basis for excitation personalization Information from late enhancement LE MRI can be used to evaluate the success of radio frequency ablation RFA procedures and interactive virtual atria pave the way for RFA planning Atrial modeling is currently in a transition from the sole use in basic research to future clinical applications The proposed methods build the framework for model based diagnosis and therapy evaluation and planning Complex models allow to understand biophysical mechanisms and enable the development of simplified models for clinical applications M W Krueger A Dorn D U J Keller F Holmqvist J Carlson P G Platonov K S Rhode R Razavi G Seemann and O Dössel In silico modeling of atrial repolarization in normal and atrial fibrillation remodeled state In Medical Biological Engineering Computing vol 51 10 pp 1105 1119 2013 request PDF doi Abstract Atrial fibrillation AF is the most common cardiac arrhythmia and the total number of AF patients is constantly increasing The mechanisms leading to and sustaining AF are not completely understood yet Heterogeneities in atrial electrophysiology seem to play an important role in this context Although some heterogeneities have been used in in silico human atrial modeling studies they have not been thoroughly investigated In this study the original electrophysiological EP models of Courtemanche et al Nygren et al and Maleckar et al were adjusted to reproduce action potentials in 13 atrial regions The parameter sets were validated against experimental action potential duration data and ECG data from patients with AV block The use of the heterogeneous EP model led to a more synchronized repolarization sequence in a variety of 3D atrial anatomical models Combination of the heterogeneous EP model with a model of persistent AF remodeled electrophysiology led to a drastic change in cell electrophysiology Simulated Ta waves were significantly shorter under the remodeling The heterogeneities in cell electrophysiology explain the previously observed Ta wave effects The results mark an important step toward the reliable simulation of the atrial repolarization sequence give a deeper understanding of the mechanism of atrial repolarization and enable further clinical investigations M Wilhelms H Hettmann M M C Maleckar J T Koivumäki O Dössel and G Seemann Benchmarking electrophysiological models of human atrial myocytes In Frontiers in Physiology vol 3 487 pp 1 16 2013 request PDF doi url Abstract Mathematical modeling of cardiac electrophysiology is an insightful method to investigate the underlying mechanisms responsible for arrhythmias such as atrial fibrillation In past years five models of human atrial electrophysiology with different formulations of ionic currents and consequently diverging properties have been published The aim of this work is to give an overview of strengths and weaknesses of these models depending on the purpose and the general requirements of simulations Therefore these models were systematically benchmarked with respect to general mathematical properties and their ability to reproduce certain electrophysiological phenomena such as action potential alternans To assess the models ability to replicate modified properties of human myocytes and tissue in cardiac disease electrical remodeling in chronic atrial fibrillation was chosen as test case The healthy and remodeled model variants were compared with experimental results in single cell 1D and 2D tissue simulations to investigate action potential and restitution properties as well as the initiation of reentrant circuits B C Schwab G Seemann R A Lasher N S Torres E M Wulfers M Arp E D Carruth J H B Bridge and F B Sachse Quantitative analysis of cardiac tissue including fibroblasts using three dimensional confocal microscopy and image reconstruction Towards a basis for electrophysiological modeling In IEEE Transactions on Medical Imaging vol 32 5 pp 862 872 2013 request PDF doi Abstract Electrophysiological modeling of cardiac tissue is commonly based on functional and structural properties measured in experiments Our knowledge of these properties is incomplete in particular their remodeling in disease Here we introduce a methodology for quantitative tissue characterization based on fluorescent labeling three dimensional scanning confocal microscopy image processing and reconstruction of tissue micro structure at sub micrometer resolution We applied this methodology to normal rabbit ventricular tissue and tissue from hearts with myocardial infarction Our analysis revealed that the volume fraction of fibroblasts increased from 4 830 42 meanstandard deviation in normal tissue up to 6 510 38 in myocardium from infarcted hearts The myocyte volume fraction decreased from 76 209 89 in normal to 73 488 02 adjacent to the infarct Numerical field calculations on three dimensional reconstructions of the extracellular space yielded an extracellular longitudinal conductivity of 0 2640 082 S m with an anisotropy ratio of 2 0951 11 in normal tissue Adjacent to the infarct the longitudinal conductivity increased up to 0 4000 051 S m but the anisotropy ratio decreased to 1 2950 09 Our study indicates an increased density of gap junctions proximal to both fibroblasts and myocytes in infarcted versus normal tissue supporting previous hypotheses of electrical coupling of fibroblasts and myocytes in infarcted hearts We suggest that the presented methodology provides an important contribution to modeling normal and diseased tissue Applications of the methodology include the clinical characterization of disease associated remodeling 1 G Lenis T Baas and O Dössel Ectopic beats and their influence on the morphology of subsequent waves in the electrocardiogram In Biomedizinische Technik Biomedical Engineering vol 58 2 pp 109 119 2013 request PDF Abstract Ventricular ectopic beats VEBs trigger a characteristic response of the heart called heart rate turbulence HRT The HRT can be used to predict sudden cardiac death in patients with a history of myocardial infarction In this work we present a reliable algorithm to detect and classify ectopic beats Every electrocardiogram ECG is processed with innovative filtering techniques artifact detection methods and a robust multichannel analysis to produce accurate annotation results For the classification task a support vec tor machine was used Furthermore a new approach to the analysis of HRT is proposed The HRT is interpreted as the response of a second order system to an external perturbation The system theoretical parameters were estimated The influence of VEB on the morphology of subsequent T waves was also analyzed A strong influence was detected in the study with 14 patients experiencing frequent VEB The evolution of the morphology of the T wave with every new beat was studied and it could be concluded that an exponential shape underlies this dynamic process and was called morphological heart rate turbulence MHRT Parameters were defined to quantify the MHRT The analysis of the MHRT could help to understand the influence of an ectopic beat on the repolarization processes of the heart and more accurately stratify the risk of sudden cardiac death E P Scholz P Carrillo Bustamante F Fischer M Wilhelms E Zitron O Dössel H A Katus and G Seemann Rotor termination is critically dependent on kinetic properties of I kur inhibitors in an in silico model of chronic atrial fibrillation In PloS one vol 8 12 pp e83179 2013 request PDF doi Abstract Inhibition of the atrial ultra rapid delayed rectifier potassium current I Kur represents a promising therapeutic strategy in the therapy of atrial fibrillation However experimental and clinical data on the antiarrhythmic efficacy remain controversial We tested the hypothesis that antiarrhythmic effects of I Kur inhibitors are dependent on kinetic properties of channel blockade A mathematical description of I Kur blockade was introduced into Courtemanche Ramirez Nattel models of normal and remodeled atrial electrophysiology Effects of five model compounds with different kinetic properties were analyzed Although a reduction of dominant frequencies could be observed in two dimensional tissue simulations for all compounds a reduction of spiral wave activity could be only be detected in two cases We

    Original URL path: http://www.ibt.kit.edu/veroeffentlichungen.php (2015-05-18)
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