1. Medical Applications Electrocardiogram (ECG)

2. 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 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

3. Professional Healthcare
ECG Markets
ECG
Professional Healthcare
Consumer
line
battery
line
battery
AED
Home Products
Commercial
Fitness Equipment
Above Diagnostic
Defibrillators
Diagnostic
Holter Monitor

4. ECG Waveform (Filtered)

5. ECG – Waveform Characteristics
ECG Signals have two components:
ECG Waveform
0.05 Hz to 150 Hz bandwidth per Medical Standards
Average R Wave Amplitude is 1.8mV
Some waveforms can be as big as 10 mV p-p.
T wave Alterans are only a few microvolts in amplitude
Pacing ArtifactS
Medical Standards require 2mV and 200µs detection
Average pulse is 1 mV and 500µs but can be much smaller

6. ECG – Patient Skin Surface Characteristics
Skin Impedance
Standards require of common mode rejection at 51K ohms skin to electrode impedance at 10Hz
Good Silver-Silver Chloride electrodes yield about 10 K ohm electrode to skin impedance
Stainless Steel electrodes can yield skin impedances of several meg-ohms
Defibrillation Voltage
5000 volts, 360 Joules
DC 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 Noise
Average is several mV

7. Signal Chains

8. Diagnostic ECG (Clinical Use)

9. Diagnostic ECG In-amp + Right Leg Drive

10. Diagnostic ECG Filters + Pace Detection

11. Diagnostic ECG ADC + Isolation + Processing

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

13. Low Cost, Low Power AED

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