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BIBEBUVAMaster of Science in Biomedical EngineeringAnalysis of Unipolar ElectrogramsThesis Advisor: Prof. Dr. Andreas Stahel, Bern University of Applied ScienceExpert: Prof Dr. med. Jan Kucera, University of Bern, Department of PhysiologyAnalysis of Unipolar Electrograms and the Detection of the Arrhythmogenetic Potential of Reference DrugsRecorded in a Langendorff Rabbit Heart PreparationChristian AffolterBackgroundThe Safety Pharmalogy Departmentof Novartis investigates theinfluence of known torsadogenicdrugs on a Langendorff in vitrorabbit heart preparation. In particularthe transmural dispersionand the apico-basal dispersion ofthe repolarization wave as well thebeat to beat variability of consecutivebeats preceding Torsades dePointes (TdP) is examined. In theexperimental setup three needles,each containing 8 electrodes, areinserted in the left ventricular wall.After the atria is removed and theHis-Bundle was cut, the heart isgetting stimulated with an electrodeplaced in the ventricularseptum where the His-Bundle iscut and the electrical propagationis recorded over these 24 electrodes.Rabbit Heart with Inserted Needles;The Picture is Provided by Dr.Nicolas Guérard, Novartis PharmaProject ScopeThe goal of this thesis was to defineand develop tools analyzingthese recorded transmural electrograms.This signal analysis canbe split up into two parts. On theone hand the filtering of the signaland on the other the parameterextraction of the electrocardiograms.The biggest challenge herewas the detection of the parameterswithin the T-wave, becausethis repolarization phase can assumeevery possible shape.ResultsThe new signal analysis of the recordedunipolar electrograms isthe main part of this thesis. In additiona graphical user interfacewas generated to facilitate the statisticalanalysis of one or moreexperiments. Thanks to the newmuch more reliable signal analysis,the added parameters and thedeveloped visualization tools, amuch better basis for an eventualdeeper pattern detection is realized.Plot of the QT-Intervals of 60 consecutivebeats before a TdP develops.DiscussionCause of the new closer look tothe signals we know now that it isnot possible to just look at sequencesright before a TdP, thenin most of the cases there are alreadyso much ectopic beatsaround, that a detection of halfwayreliable parameters is not possible.Another thing that one have totake into account with the 0.2 Hzsequence is that the steady state,after the pacing rate change from1 Hz to 0.2 Hz is reached earliestafter 30 beats and so it is not possibleto look at more than 20 beatsat steady state.40 ti.bfh.ch