STM CircleOS forum / Is that an ECG ?

House MD · 2008-02-13 19:45:41

I wonder whether this can be called ECG since it can only measure heart pulse.
Indeed, an ECG must show several waves, got thanks to 10 different electrodes at least...
Otherwise this one wave doesn't give any valuable information about heart health !
But I admit that it can be fun to see electrical activity on fingers skin.

See wikipedia to have further information ( http://en.wikipedia.org/wiki/Ecg )

Regards
[H]ouse

jingxizhang · 2008-02-18 22:29:15

Two leads should be able to detect ECG signal although 3 leads are preferred (as the wikipedia described Limb Leads, the leads I, II and III). The 2 arm leads can detect the differential signal from atrium and ventricle. The third lead can be used to inject a small feedback signal back to patient’s leg to compensate the common mode noise. The professional ECG machine has 12 leads to view the ECG from different angles (different lead pair combination), but in each channel only two leads (bipolar mode) or one lead (unipolar, reference to a virtual “center” point) are used.
There is two good papers in the web described the ECG amplifier. One is Texas Instrument App Note “Getting the most out of your instrumentation amplifier design” (http://focus.ti.com/lit/an/slyt226/slyt226.pdf). Another is Analog Device Inc paper on Analog Dialogue November 2003 “ECG Front-End Design is Simplified with MicroConverter” (http://www.analog.com/library/analogDia … 1/ecg.html). ECG Primer referenced to and is modified from those papers. To lower the power consumption, the instrument amplifier and OpAmps are selected low power version. Due to the contest rule requires less than 25 electronic components, the third lead was not used in ECG Primer (although the circuit board has the design) and the ECG wave is not as clear as it should be. But you still can see the QRS wave complex and the slow rising T-wave after QRS wave complex. The P and U waves are too small and is hard to tell from the noise. The following is the screenshot of ECG data which ECG Primer sent to PC display through the USB port. Hop this can be help.

House MD · 2008-03-06 10:45:30

What I meant is that it can't be called ECG because it has almost no medical value.
The 3 first leads of an ECG can't say anything about the heart's health. To be synthetic, I will say that this device won't be able to detect heart failures like infarct, heart rhythm disorders, and so on.
I'm afraid your device can only be a fun toy but nothing serious concerning health.

[H]ouse

jingxizhang · 2008-03-07 00:25:53

Sorry, I disagree with House’s comment for the 3-lead ECG. The 3-lead ECG has its medical value although the ECG Primer is not emphasis on its medical benefit. When I was in the medical school earlier, a portable 3-lead ECG system was the favor equipment being used. “3-Lead wire ECG system (Einthoven’s Triangle) has been around for sometime. In fact, the three lead ECG recently celebrate its 100th birthday. While the five lead ECG is gradually becoming the norm, the three lead ECG continues to be used in emergency departments, telemetry, monitoring and during medical procedures.” (www.nursecom.com). The 3-lead ECG can definitely be used for the diagnosis of cardiac arrhythmias by assessment of PP- or RR-intervals, which including the sinus arrhythmia, sinus bradycardiac, sinus tachycardiac, wandering pacemaker, paroxysmal atrial techycardiac, supraventricular arrhythmias, ventricular arrhythmias, atrial fibrillation and ventricular fibrillation. It can be also used for the diagnosis of disorders in the activation sequence by observing the relationship between P-wave and QRS-complex wave, which including different degrees of atrioventricular conduction defects (A-V blocks). The 3-lead ECG system may not suitable for atrial or ventricular enlargement and myocardiacl ischemia and infarction may require because it need more leads to look at the heart in different angles. The 12-lead system can provide more accurate information in those cases.
I never enforcing ECG Primer in medical usage is not because the 2-lead or 3-lead system. It is because that even you can get ECG traces, to interpreting the traces for diagnosis requires the good trained doctor and ECG technician, which may not be the easy task for the normal person. Also, the safety measurements (such as the isolation amplifier) will be the import issues. The ECG Primer project is not claimed to be the clinic equipment (at least not the pricing professional medical equipment) but it can be used in preventive medicine along other non-professional devices as the consumer blood pressure mornitor, the home diabetes kits and the body temperature meter. I am sure the Primer can find its way to be practically used in other fields such as biofeedback monitor. I am working on lowering its noise level to improve its performance.

Jingxi Zhang

Last edited by jingxizhang (2008-03-07 00:56:57)

Techi · 2008-05-21 19:45:30

Hi Jingxizhang,

This is really a nice project, very creative. To reduce the noise level, although it is always better to clean it at the hardware level, never the less it is also easier to write a small program to filter out the noise. Modifying a program for the cut off frequency and greater stop band attenuation is easier in software as compared in hardware. I wrote it in 1993 for my mtech project and worked amazingly. If you would like I will be more than happy to share the knowledge with you.

Also I would love to try your work and would like to buy ECG amplifier PCB if you have one in spare.

Thanks,

# 1 2008-02-13 19:45:41 Is that an ECG ?

Is that an ECG ?

# 2 2008-02-18 22:29:15 Is that an ECG ?

Re: Is that an ECG ?

# 3 2008-03-06 10:45:30 Is that an ECG ?

Re: Is that an ECG ?

# 4 2008-03-07 00:25:53 Is that an ECG ?

Re: Is that an ECG ?

# 5 2008-05-21 19:45:30 Is that an ECG ?

Re: Is that an ECG ?

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