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ECG(Electrocardiogram)
Achmad RizalBioSPIN
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Cardiac Conduction System (1)
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Cardiac Conduction System (2)
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The ECG (1)
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The ECG (1)
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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
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Holter Monitor
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Dipole Model
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Standard Location ?
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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
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The Einthoven Triangle
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Lead I
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Lead II
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Lead III
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Cardiac Vector Through the Cardiac Cycle As Seen By Leads I, II and III
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Cardiac Vector Through the Cardiac Cycle As Seen By Leads I, II and III
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Cardiac Vector Through the Cardiac Cycle As Seen By Leads I, II and III
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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?)
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Wilson’s Central Terminal
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Augmented Leads: aVR
21IIIVVaVR −−=
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Augmented Leads: aVL
21IIVVaVL −=
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Augmented Leads: aVF
2I
IIVVaVF −=
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All Frontal Leads
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Frontal Lead
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Transversal Lead
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12 Leads ECG Recording
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ECG Intrumentation
• Single Channel ECG
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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
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ECG Intrumentation
ECG Amplifier schematicsRight leg driven loop- noise reducing- patient protection- Reduce Common Mode
Voltage
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ECG Intrumentation
• Instrumentation Amplifier
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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
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ECG Intrumentation
Display Unit• Galvanometer• Osciloskop• CRT• LCD• PC + Monitor• Paper chart• PDA/HP display
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Some Problems in ECG
Noise & interferences
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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
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ECG Markets ECG
Professional Healthcare Consumer
Diagnostic
Above Diagnostic
AED
Defibrillators
Commercial Fitness Equipment
Home Products
line battery line battery
Holter Monitor
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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
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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
From Lead IIFrom Lead III
220pF
15kΩ
866kΩ
ADG620
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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
From Lead IIFrom Lead III
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
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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)
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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
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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