Extraction of Fetal Cardiac Signals from an Array of Maternal Abdominal Recordings RezaSameni Directedby: ChristianJutten MohammadB.Shamsollahi GIPSA-lab,INPG,Grenoble,France SharifUniversityofTechnology,Tehran,Iran July7,2008,Grenoble,France Overview 1outof125babiesarebornwithheartdefects [Mar,2005,Mininoetal.,2007,AHA,2008] Earlydetectionofcardiacabnormalitieshelpmedications andprecautionsduringdelivery Mostdefectsmanifestintheheart-rateandmorphology ofelectricalandmagneticcardiacsignals But,wedon’thavedirectaccesstothefetusandthefetal signalsrecordedfromthemother’sabdomenarevery weakwithhighinterferences NoninvasiveFetalCardiacSignalExtraction 2 Problem Definition Objective: Thenoninvasiveextractionoffetalcardiacsignalsfromanarrayof electrodesrecordedfromtheabdomenofapregnantwoman x 1 x     2 x (t) y (t) 1 1  x2(t)   y2(t)  xn x(t)= ..  y(t)= ..   .   .  x (t) y (t) n m x 3 Noisyobservationsignals Processedsignals x 4 Asetofelectricor magneticrecordings NoninvasiveFetalCardiacSignalExtraction 3 Outline 1 Background 2 StateoftheArt 3 Methods AnECGModelingandDenoisingFramework LinearMultichannelECGProcessing PeriodicComponentAnalysis SubspaceDecompositionbyDeflation 4 ConclusionandPerspectives NoninvasiveFetalCardiacSignalExtraction 4 Background Outline 1 Background 2 StateoftheArt 3 Methods AnECGModelingandDenoisingFramework LinearMultichannelECGProcessing PeriodicComponentAnalysis SubspaceDecompositionbyDeflation 4 ConclusionandPerspectives NoninvasiveFetalCardiacSignalExtraction 5 Background The Electrocardiogram Electrocardiogram(ECG):Overallelectricalactivityoftheheartrecorded fromthebodysurface R R R R TheR-peaksoftheECGareusedtoextracttheheart-beat NoninvasiveFetalCardiacSignalExtraction 6 Background What is the Vectorcardiogram? Vectorcardiogram(VCG):A3DrepresentationoftheECG, reconstructedfrom3ECGleads VCGoforthogonalECGleadsgivedipoleapproximationsforbody surfacepotentials: φ(t)≈a s (t)+a s (t)+a s (t) 1 1 2 2 3 3 NoninvasiveFetalCardiacSignalExtraction 7 StateoftheArt Outline 1 Background 2 StateoftheArt 3 Methods AnECGModelingandDenoisingFramework LinearMultichannelECGProcessing PeriodicComponentAnalysis SubspaceDecompositionbyDeflation 4 ConclusionandPerspectives NoninvasiveFetalCardiacSignalExtraction 8 StateoftheArt History of Fetal Electrocardiography 1906: M.CremerobservedthefetalECGusingstringgalvanometers [Cremer,1906] 1950’s: Improvementsinmeasurementandamplificationtechniques [Lindsley,1942] 1970’s: Introductionofsignalprocessingtechniquesinthisdomain [Farvet,1968,Widrowetal.,1975] 1990’s: Applicationofmultichannelsignalprocessinginthisdomain [vanOosterom,1986,Kanjilaletal.,1997,Zarzosoetal.,1997] Theproblemhassincebeenconsideredinbiomedicalandsignal processingcommunities.... NoninvasiveFetalCardiacSignalExtraction 9 StateoftheArt Objectives Fetalheart-rateanalysis[Wakai,2004] FetalECGmorphologyanalysis NoninvasiveFetalCardiacSignalExtraction 10