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A Portable Tele-Emergent System With ECG A Portable Tele-Emergent System With ECG Discrimination in SCAN DevicesDiscrimination in SCAN Devices

SpeakerSpeaker ：： Ren-Guey LeeRen-Guey LeeDate Date ：： 2004 Auguest 252004 Auguest 25

B.E. LABB.E. LAB

National Taipei University of TechnologyNational Taipei University of TechnologyComputer and Communication EngineeringComputer and Communication Engineering

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OutlineOutline

IntroductionIntroductionSystem FunctionsSystem FunctionsSystem ArchitectureSystem ArchitectureQRS Detection AlgorithmQRS Detection AlgorithmECG Discrimination AlgorithmECG Discrimination AlgorithmResults and ConclusionResults and ConclusionReferencesReferences

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IntroductionIntroduction

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ECG provides information of ECG provides information of condition of heart. condition of heart.

The system concept that under The system concept that under existing GSM communication existing GSM communication system using SMS and Tele-system using SMS and Tele-emergence device.emergence device.

Features of the device are light, Features of the device are light, compact and wireless.compact and wireless.

IntroductionIntroduction

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System functionSystem function

Tele-emergence systemTele-emergence system integrates :integrates :

ECG signals acquisition circuit. ECG signals acquisition circuit.

ECG discrimination technology.ECG discrimination technology.

Sensor Network technology.Sensor Network technology.

GSM communication system.GSM communication system.

Bluetooth communication technology.Bluetooth communication technology.

GPS position service.GPS position service.B.E. LABB.E. LAB

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System Architecture System Architecture

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Local ServerPC

Centralized PCGSM Module

Bluetooth Module

User Integration Device

electrode

Sensor Network SERVER

MSP 430

A/D Converter

LCD Touch Panel

ECG

Acquisit

ion

Circuit

Bluetooth Module

GPS Module

USER

GSM Module

Bluetooth

Bluetooth

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QRS Detection AlgorithmQRS Detection Algorithm

Most automatic ECG diagnosis Most automatic ECG diagnosis require an accurate detection of require an accurate detection of the QRS complexes.the QRS complexes.

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P

Q

R

S

T

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QRS Detection AlgorithmQRS Detection Algorithm

The QRS Detection algorithm :The QRS Detection algorithm :““Tompkins” method. Tompkins” method.

““So and Chan” method. So and Chan” method.

““Modified So and Chan” method is Modified So and Chan” method is based on “So and Chan” and based on “So and Chan” and “Tompkins” QRS detection “Tompkins” QRS detection algorithms.algorithms.

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Low-pass filterLow-pass filter ：：

Cut-off frequencyCut-off frequency ：： 12 Hz12 Hz DelayDelay ：： 5 points5 points GainGain ：： 3636

QRS Detection Algorithmcontinue

TnTxTnTxnTxTnTyTnTynTy 126222

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High-pass filterHigh-pass filter ：：

Cut-off frequencyCut-off frequency ：： 5 Hz5 HzDelayDelay ：： 16 points16 pointsGainGain ：： 3232

QRS Detection Algorithmcontinue

TnTxnTxTnTyTnTxnTy 321632

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The slope of the ECG wave is obtained by :The slope of the ECG wave is obtained by :

Let X(n) represent the amplitude of the ECG data at dLet X(n) represent the amplitude of the ECG data at discrete time n.iscrete time n.

2)2X(n1)X(n(n-1)-2X(n-2)-Xslope(n)

QRS Detection Algorithmcontinue

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The slope threshold is given by :The slope threshold is given by :

The thresh_param can set as 2,4,8,16.The thresh_param can set as 2,4,8,16.The initial maxi is the maximum slope within thThe initial maxi is the maximum slope within the first 250 data points in the ECG file.e first 250 data points in the ECG file.

maxi16

amthresh_parshslope_thre

QRS Detection Algorithmcontinue

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Detection QRS onset have two case :Detection QRS onset have two case :

1. 1. (Set (Set Max = True)Max = True)

2. 2. (Set Max = False)(Set Max = False)

When two consecutive ECG data satisfy above When two consecutive ECG data satisfy above condition, the QRS onset point has been condition, the QRS onset point has been detected.detected.

threshslopenslope _)(

2^_2)^( threshslopenslope

QRS Detection Algorithmcontinue

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Maxi is then updated by Maxi is then updated by

The filter_param can be set as 2,4,8,16.The filter_param can be set as 2,4,8,16.

)1()1(

)(-

xx

x maxiamfilter_par

maxifirst_maxmaxi

|)(| onset QRS point Rfirst_max

QRS Detection Algorithmcontinue

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QRS Detection Algorithmcontinue

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MIT-BIH ECG database

Error Detection

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“o”:R波位置 “x”:正向QRS onset 於心電曲線位置 “+”:反向QRS onset 於心電曲線位置

QRS Detection Algorithm(2)

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ECG Discrimination technology is based on :

QRS detection algorithm. Geometric correlation coefficient.

ECG Discrimination AlgorithmECG Discrimination Algorithm

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Heart Rate Variability (HRV) formula:

ECG Discrimination AlgorithmECG Discrimination Algorithmcontinuecontinue

60int_/_ ervalRRRateSampleHRV

RR_interval 1 RR_interval 2 RR_interval 3

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Correlation Coefficient :Correlation Coefficient :

n : size of the sample pointsn : size of the sample pointsxi : Templatexi : Templateyi : Sampleyi : Samplemx,xy : mean valuemx,xy : mean value

myymxx

myymxxcorr_coeff

n

1i

i2n

1i

i2

n

1i

ii

ECG Discrimination AlgorithmECG Discrimination Algorithmcontinuecontinue

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ECG ECG Discrimination Discrimination AlgorithmAlgorithmcontinuecontinue

HRV and Correlation coefficient (Record 119)HRV and Correlation coefficient (Record 119)

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ECG Discrimination AlgorithmECG Discrimination Algorithmcontinuecontinue

ECG template (Record 119)ECG template (Record 119)

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On average, the FD% of the “Modified On average, the FD% of the “Modified So and Chan” method is 1.11 % while So and Chan” method is 1.11 % while “So and Chan” method is 5.47%. (MIT-“So and Chan” method is 5.47%. (MIT-BIH Database 48 records)BIH Database 48 records)

Results and ConclusionResults and Conclusioncontinuecontinue

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Affected ECG discrimination accuAffected ECG discrimination accuracy factorsracy factors ：：

QRS Detection accuracy. QRS Detection accuracy. ECG Template created.ECG Template created.Threshold parameter selected.Threshold parameter selected.Noise interferenceNoise interferenceECG baseline wanderECG baseline wander

Results and ConclusionResults and Conclusioncontinuecontinue

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Results and ConclusionResults and Conclusion

User integration device has six User integration device has six parts : parts :

ECG acquisition circuit.ECG acquisition circuit.

Bluetooth module.Bluetooth module.

GPS module.GPS module.

GSM module.GSM module.

Touch panel.Touch panel.

MSP 430.MSP 430.

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Results and ConclusionResults and Conclusion

Sending ECG wave in terms Sending ECG wave in terms of ASCI code from SCAN of ASCI code from SCAN devicedevice

Plot the ECG wave in PCPlot the ECG wave in PC

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Next steps and Problems

Implement R-wave detection and Implement R-wave detection and Correlation Coefficient in SCAN Correlation Coefficient in SCAN devicedevice

Time complexity of algorithm must Time complexity of algorithm must be too high when implementing be too high when implementing Correlation CoefficientCorrelation Coefficient

May find other methods suitable for May find other methods suitable for sensor networksensor network

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Next steps and Problems

Power-saving issue should be Power-saving issue should be consideredconsidered

From routing protocol ?From routing protocol ?

From MAC protocol ?From MAC protocol ?Collision problems

Overhearing problems

Control package overhead problems

Idle listening problems

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ReferencesReferencesP. Jiapu and W. J. Tompkins., “P. Jiapu and W. J. Tompkins., “A Real-Time QRS DetectiA Real-Time QRS Detection Algorithmon Algorithm,” ,” IEEE trans. on bio-medical engineeringIEEE trans. on bio-medical engineering, , Vol. 32, No. 3, pp. 230-236, March 1985.Vol. 32, No. 3, pp. 230-236, March 1985.G. M. Friesen, T. C. Jannett, et al., “G. M. Friesen, T. C. Jannett, et al., “A comparison of the A comparison of the noise sensitivity of nine QRS detection algorithmsnoise sensitivity of nine QRS detection algorithms,” ,” IEIEEE Trans. on Biomedical EngineeringEE Trans. on Biomedical Engineering, Vol. 37, pp. 85- 98, J, Vol. 37, pp. 85- 98, Jane 1990. ane 1990. K. F. Tan, K. L. Chan and K. Choi, “K. F. Tan, K. L. Chan and K. Choi, “Detection of the QRS Detection of the QRS complex, P wave and T wave in electrocardiogramcomplex, P wave and T wave in electrocardiogram, “, “PrProcessing of 2000 IEE Conference on Advances in Medical Socessing of 2000 IEE Conference on Advances in Medical Signal and Information Processingignal and Information Processing, pp. 41-47, Sept 2000., pp. 41-47, Sept 2000.H.H. So and K.L. Chan, “H.H. So and K.L. Chan, “Development of QRS detection Development of QRS detection method for real-time ambulatory cardiac monitormethod for real-time ambulatory cardiac monitor,” ,” PrProceedings of the 19th Annual International Conference of oceedings of the 19th Annual International Conference of the IEEE in Engineering in Medicine and Biology societythe IEEE in Engineering in Medicine and Biology society, , Vol. 1, Oct. 1997, pp. 289-292.Vol. 1, Oct. 1997, pp. 289-292.

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H. A. N. Dinh, D. K. Kumar, et al.,H. A. N. Dinh, D. K. Kumar, et al., “ “Wavelets for QRS DeteWavelets for QRS Detectionction,” Engineering in Medicine and Biology Society Proce,” Engineering in Medicine and Biology Society Proceedings of the 23rd Annual International Conference of the Iedings of the 23rd Annual International Conference of the IEEE, EEE, Vol. 2,, pp. 1883-1887, Oct. 2001.Vol. 2,, pp. 1883-1887, Oct. 2001. K. T. Lai and K. L. Chan,K. T. Lai and K. L. Chan, ” ”Real-time classification of elecReal-time classification of electrocardiogram based on fractal and correlation analysestrocardiogram based on fractal and correlation analyses,,” Proceedings of the 20th Annual International Conference ” Proceedings of the 20th Annual International Conference of the IEEE in Engineering in Medicine and Biology Society, of the IEEE in Engineering in Medicine and Biology Society, Vol. 1 pp. 119-122, 1998.Vol. 1 pp. 119-122, 1998.Wei YeWei Ye et al., “Medium Access Control With Coordinated Medium Access Control With Coordinated Adaptive Sleeping for Wireless Sensor NetworksAdaptive Sleeping for Wireless Sensor Networks” IEEE/ACM TRANSACTIONS ON NETWORKING, VOL.12, NO.3, JUNE 2004Soo-Hwan Choi et al., “An Implementation of Wireless Sensor An Implementation of Wireless Sensor Network for Security System using BluetoothNetwork for Security System using Bluetooth” IEEE Transactions on , Vol. 50, No. 1, February 2004

continuecontinueReferencesReferences