Mimicing a heartbeat in sound and electrical pathways

If you set a cardiac nurse loose on a Propeller microcontroller and some parts you might not know what to expect. But we’re intrigued by the outcome of this project which looks to mimic a heartbeat’s audible and electrical traits. The post about the project is in four parts which are not linked to each other, but you can find them all, as well as a video segment demonstrating the rig after the break.

It seems that this was intended as a Halloween project, but we don’t see why it wouldn’t be interesting any time of year. The Propeller demo board is used to mimic a heartbeat with a pulsing LED. But that doesn’t seem all that awesome, so the sounds of a heartbeat were added to the program to coincide with the blinky light. Here’s where the medical training comes in: the next phase of the process was to lay out an array of LEDs on a breadboard in the shape of the human heart’s electrical system. Now you’ve got a pulsing LED, heart sounds, and a lighted animation showing how the electricity travels through the organ.

To add a little [Poe] to the project there’s also a CdS light sensor. As you approach the project you block some light from getting to the sensor and the heart rate increases.

We think the next logical step is to add a heart rate sensor, so that this can illustrate what your own heart is doing. Boom! Another project ready for the Children’s museum.


  1. TheYikes says:

    I can see some serious real world uses for something like this. I’m definitely gonna follow it’s progress.

    • Hirudinea says:

      Yea I agree, especially the heart sounds part, if you can also program this with abnormal heart sounds, long QT or whatever (I don’t know because I’m not a cardiologist) this thing could be pretty useful for training thrid world medical personal auscultation (listening to heart sounds.)

      • Alex Rossie says:

        I really don’t see any use in this from an educational point of view, perhaps to high school students.
        It’s really inaccurate anatomically and physiologically, and it doesn’t convey more information than a diagram with arrows instead of LEDs would show but it does take longer to look at and understand.

        Most important heart sounds have little to do with conduction. More to do with blood flow and anatomy (of the heart and surrounding vessels)

        Pretty though.

  2. Harry says:

    BOOM! heart explodes

  3. steaky says:

    I’ll admit i didnt look thru all the videos – so forgive me.
    But it would be cooler if the LED’s faded instead of stepped

  4. Atdiy/Tymkrs says:

    Glad you guys liked the project :) It was one of my first programming projects ever, so some of the features (fading vs stepping) is probably still beyond my knowledge. And TheYikes/Hirudinea – I’ll see how I can continue growing it.

  5. CRJEEA says:

    Very nice concept idea (:
    Maybe a future step might be to add in an anamatronic 3D pumping hart made from bits of clear balloon and drinks bottle plastic valves. And then put the LED’s in place (maybe smd and more) possibly even if it could be done fill it with semi transparent liquid too (:

  6. Andrew Smith says:

    First off, looks very pretty:)


    Not really accurate at all. Just really isn’t, and I’m no electro-physiologist.

    A great deal is wrong with this but without being to anal; the timing is entirely wrong for example the SA-AV flow is the PR interval on a ECG which should be <210ms on the other hand the QRS duration (flow through the bundle of His and bundle branches) should be less than 120ms. Where as you have the pukinje fibres conducting very slowly as though there is bifasicular block.

    The anatomy is off in terms of positioning of SA,AV and pukinje fibres is wrong even in a simplified view you'd learn at GCSE.

    When your heart races the heart beat isn't shortened (after all that would mean you pump out less blood) the gap between the beats shrinks.

    The heart sounds are closures of valves, and they happen not in time with contraction but just as it is letting off. So it goes P-wave S1 QRS S2 dystole.

    • Atdiy/Tymkrs says:

      Andrew – A few points:

      1) This was a halloween project so I wasn’t trying to make a model of it that could be used in classroom teaching. You’re right of course on the amount of time (<210ms/120ms), but this was maybe my second programming project? And I don't yet know how to make the leds light up faster. But perhaps you're right! My halloween heart seems to have both a first degree block and bundle branch block~

      2) I drew a picture of the basic locations of the SA/AV/bundle branches/Purkinje fibers based off of a textbook :). But the LEDs were limited because I only had so many pins that I could put LEDs off of. I actually thought I did a decent job with showing how the SA was at the top left, and the AV before the bundle branches. Of course technically purkinje fibers come OFF of the bundle branches, but um. LED and pin limitations :p

      3) Yeah I realized after the fact that duh, the lub-dub sounds aren't from the contractions but the closing of the valves (so I corrected myself in a comment I left on the video).

      And I was just, in general, happy that I could get a photoresistor to make leds change how they blinked :p.

    • Alex says:

      So, if you’re not an electro-physiologist, what are ya?

  7. Stan says:

    Can you simulate improper electrical activity like AFIB? And throw in a few PVC’s for good measure?

    • Atdiy/Tymkrs says:

      It would be easier to see/tell with an oscilloscope looking directly at the electrical activity (I think). When you listen to someone with afib, it just sounds out of rhythm like a drummer gone out of sync.

      • Andrew Smith says:

        Electrically AF is random electrical activity. It’d probably look like the the classic Hollywood light bulb in a thunderstorm in the atrial bit and the ventricles would work normally ( but irregularly) at a rate which is roughly constant for a patient when not treated.

        PVC’s would be very cool since they could potentially start and spread from any one of the ventricle LEDs.

  8. Clint says:

    This is an awesome start! We’ve been kicking around the idea of making a 3d model that would light up and pump, within our residency. I hope you beat us to it! Maybe we can share notes down the road!

  9. Joe Pitz says:

    @Andrew Smith, If you are a med student, then you really need to work on your bed side manner. Have you ever heard of constructive criticism?

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