Cardiac Conduction System (2) The ECG (1) - · PDF file(Electrocardiogram) Achmad Rizal...

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ECG(Electrocardiogram)

Achmad RizalBioSPIN

ARL-EL4703-Instrumentasi Biomedis 2

Cardiac Conduction System (1)


Cardiac Conduction System (2)


The ECG (1)


The ECG (1)


The ECG (1)Electrocardiography1. Standard clinical ECG (12 leads)2. VCG (3 orthogonal leads)3. Monitoring ECG (1 or 2 leads)

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Modern ECG

Figures above show how the earliest ECGs were recorded by Einthoven at 1900.Vats of salt water provided the electrical connection to the body. The string galvanometer served as the measurement instrument for recording the ECG. ARL-EL4703-Instrumentasi Biomedis 8

Electrocardiograph


Holter Monitor


Dipole Model


Standard Location ?


ECG Lead Configurations • A pair of electrodes, or a combination of several electrodes

through a resistive network that gives an equivalent pair is called a lead.

• A vector that connects a lead electrode pair is the lead vector.• If the cardiac vector M is known, the voltage generated at any

lead can be easily computed.

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Frontal Plane Bipolar LeadsEinthovenTriangle


The Einthoven Triangle


Lead I


Lead II


Lead III


Cardiac Vector Through the Cardiac Cycle As Seen By Leads I, II and III

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UnipolarMeasurements:Wilson Central Terminal

• Three additional leads are used for frontal plane measurements.

• These are the measurements at the specific electrode, with respect to a reference electrode

• One commonly used reference electrode is the Wilson Central Terminal, obtained through a resistive network, combining limb electrodes

• The new set of leads obtained by combining the standard limb electrodes to the Wilson terminal form the augmented leads

• These leads provide additional vector views of cardiac depolarization in the frontal plane. Unlike leads I, II, III, the augmented leads utilize WCT, a central negative terminal. This virtual "electrode" is calculated by the EKG computer to measure vectors originating roughly at the center of the heart.

Note that the voltage at Wilson’s terminal is zero (why?)


Wilson’s Central Terminal


Augmented Leads: aVR

21IIIVVaVR −−=

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Augmented Leads: aVL

21IIVVaVL −=


Augmented Leads: aVF

2I

IIVVaVF −=


All Frontal Leads


Frontal Lead


Transversal Lead


12 Leads ECG Recording

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ARL-EL4703-Instrumentasi Biomedis 31 ARL-EL4703-Instrumentasi Biomedis 32

ECG Intrumentation

• Single Channel ECG


ECG Intrumentation

Electrode TransducerCharacteristic :

acquiring signal with amplitude between 0.01mV – 3mVanticipate impedance till > 5 MΩsmall current leakages < 1 µ-Aresponse frequency 0.05 – 150 Hz


ECG Intrumentation

ECG Amplifier schematicsRight leg driven loop- noise reducing- patient protection- Reduce Common Mode

Voltage


ECG Intrumentation

• Instrumentation Amplifier


ECG Intrumentation

• AD620 single chip instrumentation amplifier

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ECG IntrumentationHigh Pass Filter Second Amplifier

Low Pass Filter 20 Hz

Clamper

Low Pass Filter 40 Hz

Analog subsystemARL-EL4703-Instrumentasi Biomedis 38

ECG Intrumentation

Digital Subsystem


ECG Intrumentation

Display Unit• Galvanometer• Osciloskop• CRT• LCD• PC + Monitor• Paper chart• PDA/HP display


Some Problems in ECG

Noise & interferences


Some Problems in ECG

• Souces of interference in an ECG trace– base line wander : patient movement, electrode

reposition, dry electrode, static buildup around patient

– AC noise (50 Hz) : powerline/common mode interfrence

– intermittent signal : lead connection not tight and secured, dry electrode, damage cable or lead wire

– Other Electrical interference (EI)

Another ECG System

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Glossary of Terms• AED : Automated External Defibrillator – Auto diagnosis with voice

directed treatment.• EKG/ECG: ElectroCardioGram – skin surface, heart monitor• Holter Monitor: Portable device for continuously monitoring the electrical

activity of the heart for at least 24 hours. Can be external or implantable.

• Defibrillation : Delivering a therapeutic dose of electrical energy to the heart.• T-wave alterans : A change in the shape of the heartbeat signal on an every

other beat basis that is not apparent to the naked eye.• Right Leg Drive : An operational amplifier deriving common mode voltage is

used to invert the common-mode signal and drive it back into thepatient through the right leg.

• RFI : Radio Frequency Interference• ESD : Electro Static Discharge


ECG Markets ECG

Professional Healthcare Consumer

Diagnostic

Above Diagnostic

AED

Defibrillators

Commercial Fitness Equipment

Home Products

line battery line battery

Holter Monitor


Diagnostic ECG (Clinical Use)

AD8220

InstrumentationAmplifier

+5V

-5V

A B

C

24.9kΩ24.9kΩ

AD7980

ADum240X

BlackFin

ADC

DSP

iCoupler

REF 22μF

ReferenceADR435

4.12kΩ

Additional Channels

Additional Channels

AD8618

+5V

4.7μF

14kΩ

+5V

+5V

-5V +5V

-5V

REF/2

REF/2

1MΩ

47nF

10kΩ

10kΩ

2.2pF

2.2pF

10pF

G=14

12.7kΩ 12.7kΩ

866kΩ

68pF

499kΩ

OP2177

+5V

OP2177+5V

op amps-5V

-5V

AD8618

+5V

14.5kΩ

14.5kΩ

68nF

22nF

REF/2

Low Pass 5th Order Filter at 157Hz

switchADG601

From Lead I

From Lead IIFrom Lead III

ADum240X

AD8618

+5V

19.3kΩ

19.3kΩ

33nF

33nF

220pF

REF/2Pacing Artifact

Detection Circuitry

15kΩ

Lead Detection

50kHz

866kΩ

ADG620

REF/2

AD8618

+5V

57.6kΩ1.18kΩ 14kΩ

High Pass Filter 0.033Hz G=50

1.15kΩ

4.99kΩ

33Ω

10nF


Diagnostic ECG In-amp + Right Leg Drive

AD8220

InstrumentationAmplifier

+5V

-5V

A B

C

24.9kΩ24.9kΩ

4.12kΩ

4.7μF

+5V

-5V +5V

-5V

REF/2

10kΩ

10kΩ

2.2pF

2.2pF

10pF

G=14

12.7kΩ 12.7kΩ

866kΩ

68pF

499kΩ

OP2177

+5V

OP2177+5V

op amps-5V

-5V

switchADG601

From Lead I


220pF

15kΩ

866kΩ

ADG620


Diagnostic ECG Filters + Pace Detection

AD8618

+5V

4.7μF

14kΩ

REF/2

REF/2

1MΩ

47nF

12.7kΩ

AD8618

+5V

14.5kΩ

14.5kΩ

68nF

22nF

REF/2

Low Pass 5th Order Filter at 157Hz

switchADG601


AD8618

+5V

19.3kΩ

19.3kΩ

33nF

33nF

220pF

REF/2Pacing Artifact

Detection Circuitry

Lead Detection

50kHz

866kΩ

ADG620

REF/2

AD8618

+5V

57.6kΩ1.18kΩ 14kΩ

High Pass Filter 0.033Hz G=50

1.15kΩ

4.99kΩ

33Ω

10nF


Diagnostic ECG ADC + Isolation + Processing

AD7980

ADum240X

BlackFin

ADC

DSP

iCoupler

REF 22μF

ReferenceADR435

Additional Channels

Additional Channels

+5V

ADum240X

33Ω

10nF

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Low Power, Low Cost, Wireless ECG (Holter Monitor)

ESDDefibrillation

Protection

ADuC7022

ADF702x*

ESDDefib

Protect

RLElectrode

RAElectrode

RLElectrode

AD623G=10.6

High-Pass Pole0.5Hz

0.47μF

5pF

681kΩ

499kΩ

5.23kΩ 5.23kΩ

475Ω 10kΩ

108pF

Anti-alias Filter-3dB, 1592 Hz

AdditionalDigital Filter

Level ShiftAnti-Alias

Total Gain ~ 220

G = 22.05

AD8641

AD8603

Dependent on Frequency Band Used (WMTS or ISM)


Low Cost, Low Power AED

Filterand

ProtectionNetwork

ADR365

AD7685

HighVoltage

Discharge

PowerControl

ADP1712

AD8220/4AD8606

AD8605

PatientPads

Li IonBattery

ADuC70xxor

Blackfin®

LCD Display

Single poleanti-alias

filter

Digital Filtering

Blanking


Exercise Heart Rate Monitor(Example: treadmill with heart rate monitor)

AD8692AD8692

REF

REF REF

AD8553

AD8691

High Pass Filter

ADuC70xxREF

InputProtection

+5V

40 Hz Low Pass Filter

Cardiac Conduction System (2) The ECG (1) - · PDF file(Electrocardiogram) Achmad Rizal...

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Transcript of Cardiac Conduction System (2) The ECG (1) - · PDF file(Electrocardiogram) Achmad Rizal...