detection algorithms · detection algorithms are designed to accurately detect cardiac signals,...

Mule 1Rhythm Detection / Therapy Delivery

Detection Algorithms

EMBLEMTM/ EMBLEMTM MRI S-ICD SystemAdvanced Physician Training

CRM-349608-AB JULY2016

Index

Learning Objectives


Phases of Operation

Detection Phase

Signal Filters

DetectionProfiles

Certification Phase

DetectionCertification

RateCertification

Decision Phase

Rate Analysis

ArrhythmiaClassification

Therapy Decision

Software Updates

SMART Pass Technology

AF Monitor

Reference

Rhythm Discrimination Examples

Algorithm Architecture

Brief Summary: EMBLEMTM MRI S-ICD

Detection Algorithms l Page 1



Detection Algorithms Learning Objectives

After completing this module, you should be able to:

•DescribetheprocessusedbytheEMBLEMTM S-ICD System tofilternon-cardiacS-ECGsignals.

• ExplainhowtheEMBLEM S-ICD System transitions betweendetectionprofilesastheheartratechanges.

•DescribehowtheEMBLEM S-ICD Systemcertifiestheaccuracyofheartratecalculations.

• Describethearrhythmiaanalysisstrategiesused by the EMBLEM S-ICD System to classify arrhythmiadetections.

• Describethetherapydecisionstrategyusedbythe EMBLEM S-ICD Systemtoconfirmtheneedforshocktherapy.

• DescribehowtheSMARTPassfilterreducesT-waveoversensing.

• ExplainhowtheAFMonitorhelpsdetectsilentornewonsetAFandAFprogression.



Phases of Operation

Detection algorithms are designed to accurately detect cardiac signals, ensure the detection is cardiac in nature,anddecideiftherapyiswarranted.

•Duringthedetection phase, thesystemfilters(removes) non-cardiac signals and uses rate detectionprofilestosenselikelycardiacactivations.

• Duringthecertification phase, the system confirmsthecardiacnatureofsensedactivationsand uses several algorithms to identify and correct oversensing, thereby ensuring the accuracy of heart ratecalculations.

• Duringthedecision phase, the system analyzes thecertifiedheartrateandclassifiesdetectionstodetermineifthereisashockablearrhythmia.Detections within the Conditional Shock Zone (dual zone programming) are analyzed via the three rhythm discrimination algorithms.

Theamplitudeofasubcutaneoussignal(S-ECG)issmallerthanthatofatransvenoussignal(TV-ECG)andthefrequencycontentdifferssignificantly.Theextrastepofcertificationpreventscountingofnon-cardiacsignals.

Detection algorithms are designed to accurately detect cardiac signals, ensure the detection is cardiac in nature, and decide if therapy is required.

During Automatic Setup, the system stores the patient’s NSR template for reference during arrhythmiaanalysis.

KEY CONCEPT

NOTES



Discrimination Algorithms


Signal Filters

Band Pass and Notch filters permit cardiac signals to passthroughforanalysis.

•TheBand Pass filter acceptsS-ECGsignalswithinthe cardiac frequency range and rejects signals outsidethatrange.

• TheNotch filter removespowerlinefrequencies.Thisfilterisautomaticallyconfiguredduringinitialprogramming upon selection of the Time Zone (geographicregion).InNorthAmericathesettingis60Hz;inEuropeitis50Hz.SeeFigureB.

SignalfiltersrejectS-ECGsignalsoutside the cardiac frequency range.

The programmer prompts the user to reset the Time Zone after a batterycharge.

Figure A: Signal filters Figure B: Notch filter settings

KEY CONCEPT

NOTES

Detection Phase



Detection Profiles

The EMBLEMTMS-ICDSystemtransitionsbetweendetection profilesastheheartratechanges.Dual zone programming reduces the chance of inappropriate shock (IDE Study).

• The faster the detected heart rate, the more aggressive the detection profile.

• Detection sensitivity can be adjusted by programminghigherorlowerratesfortheShock Zone (170-250 bpm) and Conditional Shock Zone (170to240bpm).

With dual zone programming, the EMBLEM S-ICD System transitions betweendetectionprofiles.

Dual zone programming

KEY CONCEPT

NOTES

Detection Phase


Detection profiles


Detection Certification

The Waveform Appraisal algorithm ensures noise detectionsarenotincludedinheartratecalculations.

•DuringWaveformAppraisal,theEMBLEMS-ICDSystem analyzes the characteristics of the detected signal.Ifnoiseissuspected,theS-ECGismarkedwithanN(noise)andtheintervalsbeforeandaftertheNarenotusedtocalculatetheheartrate.SeeFigureA.

•Example:InFigureB,theyellowdotsrepresentnoise superimposedontheNSR.Thegreendotsrepresent the certified rate. The blackdotsshowthatnoisedetectionsdonotalterthecertifiedrate.Essentially, the system cannot detect and treat arrhythmias when noise is present.

The Waveform Appraisal algorithm ensures noise detections are not includedinheartratecalculations.

Attheonemonthfollow-up,consider asking the patient to perform isometric exercises (palm press, chair raise) to assess myopotentialsensing.IftheS-ECGshowsnoisemarkers(N),evaluateothersensevectors.

Figure A: Detections Figure B: Certified Rate

KEY CONCEPT

NOTES

Certification Phase


S = certified detection N = suspect detection


Rate Certification

Rate Certification algorithms ensure double detections arenotincludedinheartratecalculations.

•Algorithm1:Static Template Analysis identifiesandcorrectsT-wavedoubledetection(alternatingmorphologypattern).Itcomparesthemorphologyof the stored NSR template to that of the last three intervals and looks for a match-nonmatch-match pattern.

•Algorithm2:Wide Complex Analysis identifiesandcorrectsdoubledetectionofwidemorphologycomplexes,whichmayoccurwithbundlebranchblock.Itlooksforarepeatingpatternofcloselycoupleddetectionsandappliesvariouscriteria.

•Algorithm3:Interval Analysis identifiesdoubledetections(widecomplexorT-wave)bylookingforapatternofalternatingintervaldurations(e.g.,long-short,long-short).

•Algorithm4: Alternating Morphology Analysis identifiesan alternating morphology pattern in a group of three successive complexes (match-nonmatch-matchpattern).It uses the stored template for width.

Overcounteddetectionsaremarkedwithadotanddiscarded.Validintervalsarecombinedintoonecertifiedinterval.

StaticTemplateAnalysisidentifiesandcorrectsT-wavedoubledetectionbasedonthestoredNSRtemplate.

WideComplexAnalysisidentifiesandcorrectsdoubledetectionofwidemorphologycomplexes.

Interval Analysis corrects oversensing by identifyingalternatingintervaldurations.

Alternating Morphology Analysis identifiesanalternatingmorphologypattern in a group of three successive complexes..

The EMBLEMTM S-ICD System manages oversensing via pre-implant patient screening, post-implant template formation, and rate certificationalgorithms.

KEY CONCEPT

NOTES

Certification Phase


Algorithm 1: Static Template Analysis

Algorithm 4: Alternating Morphology Analysis Algorithm 3: Interval Analysis

Algorithm 2: Wide Complex Analysis


Rate Analysis

Uponcertification,theEMBLEMTM S-ICD System decides if the detection falls into a non-shockable zone (NSR Mode)ortherapyzone(TachyMode).

•ThesystemtransitionsfromNSR Mode to Tachy Modewhenthecertifiedheartratereachesthelowest programmed therapyzone.

•ThesystemtransitionsfromTachy Mode to NSR Mode whentheheartrateremainsbelowthethe Hysteresis Zone (40 ms) for 24 consecutive intervals.This prevents a premature return to NSR Mode in the event of underdetection.

TachyModestartswhentheheartratereachesthelowestprogrammed therapy zone and endswhentherateismaintainedbelowtheHysteresisZonefor24intervals.

KEY CONCEPT

NOTES

Decision Phase



Arrhythmia Classification

The Arrhythmia Classification diagram showshowthe EMBLEMTMS-ICDSystemdecidesifthecertifieddetection is a normal sensed beat (S) or ventricular tachycardia(T)requiringshocktherapy.

•AllcertifieddetectionswithintheprogrammedShockZoneareconsideredshockable.

•AllcertifieddetectionswithintheConditionalShockZone are analyzed via the rhythm discrimination algorithmsasfollows:- Static Morphology compares the degree of morphologysimilaritybetweenthecurrentdetectionandthestoredNSRtemplate.

- Dynamic Morphology compares the degree of morphologysimilaritybetweentwoconsecutivedetections.

- QRS Width comparestheQRSwidthofthecurrentdetectionwiththestoredNSRtemplate.AmonomorphicarrhythmiawithawideQRSisconsideredshockable(T).OnewithanarrowQRSisconsiderednormal(S).

ArrhythmiaClassificationisusedtoidentify VT/VF episodes that require shocktherapy.

It is important to store an NSR template to ensure optimal applicationofalgorithms.

KEY CONCEPT

NOTES

Decision Phase



Therapy Decision

After identifying shockable VT/VF episodes, the EMBLEMTM S-ICD System performs several therapy decisionstepstoconfirmthepatient’sneedforshocktherapy.

•ThesystemevaluatesX/Y criteria to ensure the VT/VFepisodeissustained.X/Yisacounterthatcompares detections and compensates for double detectionsandnoise.

• SMART Charge ensurestheVT/VFepisode(X/Ycount) is sustained for a sufficient duration before charging. The nominal duration before charging is twoadditionalintervalsafterx/ycriteriaaremet(e.g.18/24).Thesystemautomaticallyextendstheduration in the presence of a non-sustained VT/VF (uptofiveextensionsandfifteenintervals).

• Charge Confirmationensuresthetwomostrecentdetections remain shockable before initiating the capacitor charge.

• Shock Confirmation ensures the VT/VF episode is still present after capacitor charging is complete. This strategy prevents unnecessary therapy for short VT runs after spontaneous VT/VF termination.

Uponshockconfirmation,theEMBLEMS-ICDSystemdeliversashocksynchronizedtothenextdetection.

Therapy Decision algorithms confirmtheneedforshocktherapy.

KEY CONCEPT

NOTES

Decision Phase



SMART Pass TechnologySoftware Updates

SMART Pass isathirdgenerationsoftwareupdatethat reduces the incidence of cardiac oversensing by applyinganadditionalHighPassfilter.

•SMARTPassreducestheamplitudeoflowfrequencysignalssuchasT-waves.ItallowshighfrequencysignalssuchasR-waves,VT,andVFtopassthrough.FigureA.

•WhenSMARTPassisOn,theEMBLEMS-ICDusestheRateCertificationalgorithmstocalculatetheheartrateasusual.Certifieddetectionsareanalyzed via the rhythm discrimination algorithms asusual.

•FigureBcomparessensingwithSMARTPassOFFandOn.WhenprogrammedOn,lowamplitudeT-wavesignalsarefilteredout.

EFFORTLESSstudyresultsatthreeyearsshowedthatS-ICDsoftwareupdatesreducedtheincidenceofinappropriateshockfrom8.1%to3.8%.1 FigureC.

Figure C: Projected effect of S-ICD detection software updates

KEY CONCEPT

NOTES

SMART Pass reduces the amplitude oflowfrequencysignals(T-waves)to reduce cardiac oversensing and inappropriateshock.


Figure A: SMART Pass Technology Figure B: SMART Pass Off vs On

Use Manual Setup to update theEMBLEMS-ICDsoftware(SeeIFU).Storeanexercisetest template to ensure optimal applicationofSMARTPass.


AF Monitor Software Updates

The AF Monitor notifiesclinicianswhenatleastsixminutesofAFhaveaccumulatedin24hours.ItisatooltohelpindiagnosingsilentornewonsetAFanditsprogression.

•TheAFMonitorusesa192beatwindowtoanalyzeandclassifythedetectedrhythm(NSRorAF).TobeclassifiedAF,atleast60%ofthebeatsinthewindowmustbeAF.TheS-ICDaddsthedurationsofallwindowsthatmeetAFcriteriatodeterminehowmanyminutesofAFaccumulatedin24hours.

•Allwindowsareanalyzedviatwoalgorithms.TheVentricular Scatter algorithm calculates beat-to-beat rate differences to determine if the rate is stable (NSR), unstable (AF), or random (PVC, double detection).Itclassifiestherhythmbasedontheratioofeventsineachratebin.*SeeFigureA.

• TheHeart Rate Density Index (HRDI) places each of the 192 beats in a histogram depicting the heartratedistribution.ItthendeterminestheHRDIandHeartRatemodeandclassifiestherhythmasNSR(narrowdistribution,slowerrate)orAF(widerdistribution,fasterrate).SeeFigureA.

Collected AF Monitor data (number of days; number of minutes per day) can be accessed from the programmer for90daysandfromLatitudeNXTfor100days. *Astablerhythmvaries less than 5 bpm from beat to beat.Anunstablerhythmvaries morethan5bpm.

KEY CONCEPT

NOTES

The AF Monitor uses a 192 beat windowandtwoalgorithmstodeterminehowmanyminutesofAFaccumulatedin24hours.


Thedurationofa192beatwindowisaboutthreeminutesat60bpm.

When programmed On, the AF MonitoroperatesevenwhentachytherapyisprogrammedOff.

BenchtestingshowedthattheAFMonitorhasasensitivity≥87%andapositivepredictivevalue≥90%.2

Figure A: AF algorithms: Ventricular Scatter, Heart Rate Density Index (HRDI)


Discrimination ExampleReference

NSR to shockable polymorphic VT

•Static morphology (red): decreased correlation to NSR template

•Dynamic morphology (green): beat-to-beat dissimilarity

•QRSwidth(pink):widerthanNSR

KEY CONCEPT

NOTES

NSR to shockable polymorphic VT



Discrimination Example Reference

NSR to monomorphic VT

•Static morphology (red): decreased correlation to NSR template

•Dynamic morphology (green): beat-to-beat similarity

•QRSwidth(notshown):IfQRSwidenscomparedtoNSR, shock therapy is required

KEY CONCEPT

NOTES

NSR to monomorphic VT



Discrimination ExampleReference

NSR to shockable VT

•Static morphology (red): drops during VT

• Dynamic morphology (green): remains high during beat-to-beat

•QRSwidth(pink):isnarrowduringNSRandwideduring VT

KEY CONCEPT

NOTES

NSR to shockable VT



Algorithm Architecture Summary

Summary of arrhythmia evaluation:

•Detection Phase The EMBLEMTM S-ICD System filters(removes)non-cardiacsignalsandusesrate-dependentdetectionprofilestosenselikelycardiacactivations.

• Certification Phase The EMBLEM S-ICD System certifiesdetectionsviaWaveformAppraisal;thencertifiestheheartrateviaoversensingalgorithms.

•Decision Phase The EMBLEM S-ICD System analyzes the rate to identify possible tachyarrhythmias; then analyzes subsequent detections using discrimination algorithmsandX/Ycriteriatodecideiftherapyisnecessary.

Phases of arrhythmia detection1.Detectcardiacsignals2.Certifydetections3.Decideiftherapyisneeded

KEY CONCEPT

NOTES

Reference


The discrimination algorithms apply only to the Conditional Shock Zone (dual zone programming).


References

1.TheunsD,etal.EvaluationofanovelalgorithmdesignedtoreduceoversensingintheS-ICD.HRS.2016:AB05-01.

2.EMBLEMS-ICD,EMBLEMS-ICDUsersManual.359480-001EN.US2015:11.

Detection Algorithms l References



Indications for UseTheS-ICDSystemisintendedtoprovidedefibrillationtherapyforthetreatmentoflife-threateningventriculartachyarrhythmiasinpatientswhodonothavesymptomaticbradycardia,incessant ventricular tachycardia, or spontaneous, frequently recurring ventricular tachycardia thatisreliablyterminatedwithanti-tachycardiapacing.

ContraindicationsUnipolarpacingandimpedance-basedfeaturesarecontraindicatedforusewiththeS-ICDSystem.

WarningsRead the manual thoroughly before using the S-ICD System to avoid damage to the pulse generatorand/orsubcutaneouselectrode.Suchdamagecanresultinpatientinjuryordeath.Forsinglepatientuseonly.Donotreuse,reprocess,orresterilize.AllBostonScientificS-ICDimplantablecomponentsaredesignedforusewiththeBostonScientificS-ICDSystemonly.ConnectionofanyS-ICDSystemcomponentstoanon-compatiblecomponentwillresultinfailuretodeliverlife-savingdefibrillationtherapy.AlwayshaveexternaldefibrillationequipmentandmedicalpersonnelskilledinCPRavailableduringimplantandfollow-uptesting.Usingmultiple pulse generators could cause pulse generator interaction resulting in patient injury or alackoftherapydelivery.Testeachsystemindividuallyandincombinationtohelppreventundesirableinteractions.ConcomitantuseoftheS-ICDSystemandimplantedelectromechanicaldevices (for example a ventricular assist device, VAD; or implantable insulin pump or drug pump) can result in interactions that could compromise the function of the S-ICD, the co-implanteddevice,orboth.Electromagnetic(EMI)ortherapydeliveryfromtheco-implanteddevicecaninterferewithS-ICDsensingand/orrateassessment,resultingininappropriatetherapyorfailuretodelivertherapywhenneeded.Inaddition,ashockfromtheS-ICDpulsegeneratorcoulddamagetheco-implanteddeviceandcompromiseitsfunctionality.Tohelppreventundesirableinteractions,testtheS-ICDsystemwhenusedincombinationwiththeco-implanteddevice,andconsiderthepotentialeffectofashockontheco-implanteddevice.HandlethecomponentsoftheS-ICDSystemwithcareatalltimesandmaintainpropersteriletechnique.Donotmodify,cut,kink,crush,stretchorotherwisedamageanycomponentoftheS-ICDSystem.Usecautionhandlingthesubcutaneouselectrodeconnector.Donotdirectlycontacttheconnectorwithanysurgicalinstrumentssuchasforceps,hemostats,orclamps.Use appropriate anchoring techniques as described in the implant procedure to prevent S-ICD Systemdislodgementand/ormigration.DonotimplantinMRIsiteZoneIII.Usecautionwhenplacing a magnet over the S-ICD pulse generator because it suspends arrhythmia detection and therapyresponse.Inpatientswithadeepimplantplacement(greaterdistancebetweenthemagnetandthepulsegenerator)magnetapplicationmayfailtoelicitthemagnetresponse.DonotexposeapatientwithanimplantedS-ICDSystemtodiathermy.EMBLEMS-ICDdevicesareconsideredMRConditional.UnlessallMRIConditionsofUsearemet,MRIscanningofthepatientdoesnotmeetMRConditionalrequirementsfortheimplantedsystem.TheProgrammerisMRUnsafeandmustremainoutsidetheMRIsiteZoneIII.DuringMRIProtectionModetheTachycardiatherapyissuspended.MRIscanningafterERIstatushasbeenreachmayleadtoprematurebatterdepletion,ashorteneddevicereplacementwindow,orsuddenlossoftherapy.TheBeepermaynolongerbeusablefollowinganMRIscan.ItisstronglyrecommendedthatpatientsarefollowedonLATITUDENXTafteranMRIscaniftheyarenotalready.Advisepatients to seek medical guidance before entering environments that could adversely affect the operationoftheactiveimplantablemedicaldevice,includingareasprotectedbyawarningnoticethatpreventsentrybypatientswhohaveapulsegenerator.Thepulsegeneratormaybemoresusceptibletolowfrequencyelectromagneticinterferenceatinducedsignalsgreaterthan80uV.TheS-ICDSystemhasnotbeenevaluatedforpediatricuse.



PrecautionsForspecificinformationonprecautions,refertothefollowingsectionsoftheproductlabeling: clinical considerations, sterilization and storage, implantation, device programming, environmental and medical therapy hazards, hospital and medical environments, home andoccupationalenvironments,follow-uptesting,explantanddisposalandsupplementalprecautionaryinformation.

Advise patients to avoid sources of EMI because EMI may cause the pulse generator to deliver inappropriatetherapyorinhibitappropriatetherapy.

Potential Adverse Events Potential adverse events related to implantation of the S-ICD System may include, but are not limitedto,thefollowing:Acceleration/inductionofatrialorventriculararrhythmia,adversereaction to induction testing, allergic/adverse reaction to system or medication, bleeding, conductor fracture, cyst formation, death, delayed therapy delivery, discomfort or prolonged healing of incision, electrode deformation and/or breakage, electrode insulation failure, erosion/extrusion, failure to deliver therapy, fever, hematoma/seroma, hemothorax, improper electrodeconnectiontothedevice,inabilitytocommunicatewiththedevice,inabilitytodefibrillateorpace,inappropriatepostshockpacing,inappropriateshockdelivery,infection,keloid formation, migration or dislodgement, muscle/nerve stimulation, nerve damage, pneumothorax, post-shock/post-pace discomfort, premature battery depletion, random component failures, stroke, subcutaneous emphysema, surgical revision or replacement of the system,syncope,tissueredness,irritation,numbnessornecrosis.

PatientswhoreceiveanS-ICDSystemmaydeveloppsychologicaldisordersthatinclude,butarenotlimitedto,thefollowing:depression/anxiety,fearofdevicemalfunction,fearofshocks,phantomshocks.

ForalistofallpotentialadverseeventsassociatedwithMRIscanning,refertotheMRITechnicalGuide. Refer to the product labeling for specific indications, contraindications, warnings/precautions and adverse events. Rx only. (Rev A)

detection algorithms · detection algorithms are designed to accurately detect cardiac signals,...

Documents