non invasive diagnosis of cardiac arrhythmia, coronary artery disease through fingertip ...

84 Pages·2017·0.87 MB·English

NON INVASIVE DIAGNOSIS OF CARDIAC ARRHYTHMIA,
CORONARY ARTERY DISEASE THROUGH FINGERTIP
PHOTOPLETHYSMOGRAPHY
Thesissubmittedinpartialfulfillment
oftherequirementsforthedegreeof
MasterofScience
in
ELECTRONICSANDCOMMUNICATIONSENGINEERINGby
RESEARCH
by
NEERAJSUDHIRPARADKAR
201232533
[email protected]
InternationalInstituteofInformationTechnology
Hyderabad-500032,INDIA
JUNE2017
Copyright(cid:13)c NEERAJSUDHIRPARADKAR,2017
AllRightsReserved

ToMyparentsandfriends
Acknowledgments
Foremost,IexpressmythanksandgratitudetomythesisadvisorDr. ShubhajitRoyChowdhuryfor
his continuous advice he provided me throughout the course of my time here. Without his motivation
and support, it would have not been possible for me to continue my work till the final stages. I would
nothavesubmittedthisthesisifnotforhisimmensepatiencewithme.
The time I spent here was made truly memorable by my friends Ajinkya, Lipika, Falak, Koustav,
Harit, Prateek, Bhuvanan, Gopi, Mihir, Lokesh, Gaurav and the list goes on and on. Thank you all for
beingwithmethrougheverythingandIwillalwayscherishallthememorieswithyouguys.
I can not thank my parents enough for providing me with unconditional love, trust and patience. It
wasalongjourneyandyoumadeitpossible. Iexpressmyinfinitegratitudetothemforbringingmeto
lifeinthisuniverse.
FinallyIthankmyinstituteforprovidingmewiththisopportunitytocarryoutresearchandshaping
upmycareer.
v
Abstract
Healthy heart is a key for healthy life. Unfortunately in many cases the heart function deteriorates
overaperson’slifetime,oftenwithtragicconsequences. Aclassofdiseasesinvolvingheartfunctionality
istermedcardiovasculardisease. Amonganumberofsuchcardiovasculardiseases,cardiacarrhythmia
andcoronaryarterydisease(CAD)aretwoofthemostcommonandpotentiallylifethreateningdiseases
and are the our work is focussed around them. A primary reason for a high casualty figures caused by
thesediseasescanbeattributedtothefactthatthediagnosisisnotdoneontime. Often,thesymptomsare
noticeableonlyatastagewherethepersonneedsimmediatemedicalattention. Accuratediagnosiscan
only be done at specialized healthcare facilities by trained personnel. The diagnosis is also expensive.
This limits its accessibility for major portion of population especially in rural areas. State of the art
diagnosisforcoronaryarterydiseasetypicallyinvolvesaninvasiveprocedure. Thoughthisprocedureis
conclusive,itisstillpainfulandrisky. Assessingthesechallenges,thereisaneedforawidelyaccessible,
inexpensiveandpreferablynoninvasivealternative.
Whilelookingforalternatives,electrocardiographyorECGhasadvantagesofbeingaccessible,non-
invasive, and inexpensive. It is used for diagnosing cardiac arrhythmia, and as a screening test for
coronaryarterydisease. Howeverthisscreeningisinconclusiveandothertechniquesarerecommended.
Anothernoninvasivetechnique,phonocardiographyorPCGsuffersfromcomplexdesignandsensitive
equipment. Which brings us to yet another well known technique, most commonly used for pulse
oximetry, the photoplethysmography (PPG). Photoplethysmography can be defined as study of blood
volume changes through light. It is non invasive, inexpensive and can easily be made portable thus
makinganidealcandidateforfurtherinvestigation. PPGisalsoverysuitableforuseinwearabledevices
technologyandsuchdevicesareusedforambulatorymonitoring. Havingallthedesiredcharacteristics,
PPG is further investigated towards diagnosing cardiac diseases. As PPG as a technique already exists
andiswidelyused,thisworkisaimedatdevelopingtechniquestoanalysethePPGdatatowardspossible
diagnosisofcardiacdiseases.
Phtoplethysmography has its own challenges. It has high sensitivity and susceptibility to motion.
Thisisparticularlyconcerningfordetectingarrhythmiaandcoronaryarterydiseasealikeasitwrongly
affectsheartbeatdetectionaswellasdegradesthenaturalcharacteristicsofthesignal. Firstcontribution
of this work is a technique to estimate heart rate in presence of motion induced artifcats using fuzzy
entropy of the signal. Once accurate heart rate is estimated, the input signal is tested for possible
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cardiac arrhythmias such as tachycardia, bradycardia, asystole, ventricular tachycardia and ventricular
fibrillation.
The fuzzy entropy based method poses some implementation limitations as it is computationally
inefficientandrequiresinitialuserinput. Anotherapproachisdevelopedtoovercometheselimitations.
Aqualityindexisassignedtoeachpulse. Theartifactportionisremovedusinganappropriatethreshold.
Theremainingcleanportionofthesignalisusedforarrhythmiadetection. Thistechniqueisfasterand
moreaccuratethanfuzzyentropybasedtechniqueandmuchmoreusefulforarrhythmiadetection.
AnotherimportantcontributionofthisworkistoexplorePPGfordetectingcoronaryarterydisease.
This involves analysing the morphology of the PPG signal and its second derivative. Characteristic
points are obtained from the PPG waveform and its second derivative. Temporal position of these
characteristic points is used as a distinguishing feature to classify between healthy subjects and CAD
patients. Thisanalysisiscarriedoutusinginvasivearterialbloodpressure(ABP)signalaswell. Super-
visedclassificationusingsupportvectormachineisemployedforclassifyinghealthysubjectsandCAD
patients. It is observed that higher classification accuracy was obtained using PPG signal compared to
ABP. Despite certain limitations, we present proof to suggest that PPG can be effective in detecting
certaincardiacarrhythmiasandcoronaryarterydisease.
Contents
Chapter Page
1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.1 Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.1.1 Arrhythmia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1.2 PathophysiologyofArrhythmia . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1.3 Tachycardia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1.4 Bradycardia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1.5 Asystole . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1.6 VentricularFibrillation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1.7 Symptoms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1.8 Diagnosis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1.8.1 Holtermonitor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1.8.2 Echocardiogram . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1.8.3 Stresstest . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1.9 CoronaryArteryDisease . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1.10 PathophysiologyofCAD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.1.11 Diagnosis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.1.11.1 CoronaryAngiography . . . . . . . . . . . . . . . . . . . . . . . . 5
1.1.11.2 Electrocardiography(ECG) . . . . . . . . . . . . . . . . . . . . . . 6
1.1.11.3 StressTesting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
1.1.11.4 CardiacComputedTomographyAngiography(CTCA) . . . . . . . 6
1.1.11.5 Echocardiography . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
1.1.11.6 Intravascularultrasound . . . . . . . . . . . . . . . . . . . . . . . . 6
1.2 Motivation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
1.3 PreviousWork . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
1.4 ScopeandContribution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
1.5 Organization. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
2 OverviewofFingertipPhotoplethysmography: ProspectsandChallenges . . . . . . . . . . . 12
2.1 PhotoplethysmographyFundamentals . . . . . . . . . . . . . . . . . . . . . . . . . . 12
2.2 ClinicalPhysiologicalMonitoring . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
2.2.1 BloodOxygenSaturation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
2.2.2 BloodGlucose,Haemoglobin . . . . . . . . . . . . . . . . . . . . . . . . . . 13
2.2.3 HeartRate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
2.2.4 BloodPressureMeasurement . . . . . . . . . . . . . . . . . . . . . . . . . . 14
2.2.5 RespiratoryRate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
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CONTENTS ix
2.3 VascularAssessment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
2.3.1 ArterialHealth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
2.3.2 EndothelialFunction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
2.3.3 MicrovascularBloodFlowAndTissueViability . . . . . . . . . . . . . . . . 15
2.4 Challenges. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
2.4.1 Noise . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
2.4.2 AmplitudeVariationsofPPGSignal . . . . . . . . . . . . . . . . . . . . . . . 16
2.4.3 MotionInducedArtifact . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
3 MotionArtifactsRemovalAndCardiacArrhythmiaDetectionUsingFuzzyEntropy . . . . . 17
3.1 RelatedWork . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
3.2 FuzzyEntropyBasedMotionArtifactDetection . . . . . . . . . . . . . . . . . . . . . 18
3.2.0.1 PeakIdentification . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
3.2.0.2 EntropyCalculation . . . . . . . . . . . . . . . . . . . . . . . . . . 18
3.2.0.3 Classification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
3.3 EntropyMeasureOfFuzziness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
3.3.1 ModifiedEntropyMeasure . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
3.4 MotionArtifactDetection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
3.4.1 Dataset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
3.4.2 Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
3.5 ArrhythmiaDetection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
3.5.1 Dataset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
3.5.2 ArrhythmiaDetectionUsingPulseRate(bpm) . . . . . . . . . . . . . . . . . 30
3.5.3 Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
3.6 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
4 PulseQualityEstimationUsingPPGMorphologyandItsApplications . . . . . . . . . . . . 33
4.1 RelatedWork . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
4.2 ProposedMethod . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
4.2.1 PeakIdentification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
4.2.2 SpectralResidualRepresentation . . . . . . . . . . . . . . . . . . . . . . . . 34
4.2.3 GaussianFit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
4.2.3.1 PhysiologyofPPGsignal . . . . . . . . . . . . . . . . . . . . . . . 35
4.2.3.2 PPGAsSumofGaussianFunctions . . . . . . . . . . . . . . . . . 37
4.2.4 NumberofPeaks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
4.2.5 FeatureVector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
4.2.6 QualityEstimation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
4.3 MotionArtifactDetection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
4.3.1 Dataset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
4.3.2 Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
4.4 ArrhythmiaDetection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
4.4.1 Dataset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
4.4.2 Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
4.5 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
x CONTENTS
5 DetectionofCoronaryArteryDiseaseUsingSignalMorphology . . . . . . . . . . . . . . . 45
5.1 ArterialBloodPressure(ABP) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
5.2 ArterialAgeing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
5.3 MorphologicalAnalysisUsingSecondDerivative . . . . . . . . . . . . . . . . . . . . 47
5.4 ProposedMethod . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
5.5 RepresentativePulseExtraction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
5.5.1 PreprocessingandPulseSegmentation . . . . . . . . . . . . . . . . . . . . . 48
5.5.2 FundamentalsofSVD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
5.5.3 EstimationofDominantPeriodicComponentandRepresentativePulse . . . . 49
5.6 MorphologicalAnalysisofRepresentativePulse . . . . . . . . . . . . . . . . . . . . . 50
5.7 MorphologicalAnalysisofSecondDerivativeofRepresentativePulse . . . . . . . . . 50
5.7.1 WaveletTransform . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
5.7.2 SelectionofWaveletFunction . . . . . . . . . . . . . . . . . . . . . . . . . . 52
5.7.3 WaveletTransformofPPGwaveform . . . . . . . . . . . . . . . . . . . . . . 52
5.7.4 LocalExtremaDetection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
5.8 CADDetection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
5.8.1 DatasetsUsed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
5.8.2 MorphologyofPatientandHealthySubjectData . . . . . . . . . . . . . . . . 54
5.8.3 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
5.8.4 Classification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
5.9 Results. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
5.9.1 Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
5.10 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
6 ConclusionsAndFutureWork . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
6.1 ThesisSummary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
6.2 FutureWork . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63