medical applications-ecg
TRANSCRIPT
The World Leader in High Performance Signal Processing Solutions
Medical ApplicationsElectrocardiogram (ECG)
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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 the patient 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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ECG Waveform (Filtered)
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ECG – Waveform Characteristics
ECG Signals have two components: ECG Waveform
0.05 Hz to 150 Hz bandwidth per Medical StandardsAverage R Wave Amplitude is 1.8mVSome waveforms can be as big as 10 mV p-p.T wave Alterans are only a few microvolts in amplitude
Pacing ArtifactMedical Standards require 2mV and 200µs detectionAverage pulse is 1 mV and 500µs but can be much smaller
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ECG – Patient Skin Surface Characteristics
Skin ImpedanceStandards require of common mode rejection at 51K ohms skin to
electrode impedance at 10HzGood Silver-Silver Chloride electrodes yield about 10 K ohm
electrode to skin impedanceStainless Steel electrodes can yield skin impedances of several
meg-ohmsDefibrillation Voltage
5000 volts, 360 JoulesDC Voltage
Medical Standards require being capable of acquiring ECG with 300 mV of DC. Mostly due to half cell potential of electrodes, stainless steel can yield 500 mV of DC
60 Hz NoiseAverage is several mV
The World Leader in High Performance Signal Processing Solutions
Signal Chains
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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
LowPass 5th OrderFilterat 157Hz
switchADG601
FromLead I
FromLead IIFromLead III
ADum240X
AD8618
+5V
19.3kΩ
19.3kΩ
33nF
33nF
220pF
REF/2Pacing Artifact
Detection Circuitry
15kΩ
LeadDetection
50kHz
866kΩ
ADG620
REF/2
AD8618
+5V
57.6kΩ1.18kΩ 14kΩ
HighPassFilter 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
FromLead I
FromLead IIFromLead III
220pF
15kΩ
866kΩ
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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
LowPass 5th OrderFilterat 157Hz
switchADG601
FromLead IIFromLead III
AD8618
+5V
19.3kΩ
19.3kΩ
33nF
33nF
220pF
REF/2Pacing Artifact
Detection Circuitry
LeadDetection
50kHz
866kΩ
ADG620
REF/2
AD8618
+5V
57.6kΩ1.18kΩ 14kΩ
HighPassFilter 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)
ESDDefibrillationProtection
ADuC7022
ADF702x*
ESDDefib
Protect
RLElectrode
RAElectrode
RLElectrode
AD623G=10.6
High-PassPole0.5Hz
0.47μF
5pF
681kΩ
499kΩ
5.23kΩ 5.23kΩ
475Ω 10kΩ
108pF
Anti-aliasFilter-3dB, 1592Hz
AdditionalDigitalFilter
Level ShiftAnti-Alias
TotalGain ~ 220
G = 22.05
AD8641
AD8603
Dependent onFrequency BandUsed(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
HighPassFilter
ADuC70xxREF
InputProtection
+5V
40HzLowPassFilter