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Model S and Pacemakers

Discussion in 'Model S' started by Geezer, Oct 7, 2015.

  1. Geezer

    Geezer New Member

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    My wife and I recently purchased a new MS70 and we love it! I just learned this week, during a visit to my cardiologist, that I need to get a pacemaker. I checked the Tesla Owner's Manual and discovered a warning about possible interference between the keyless antennas and pacemakers. Ouch! I have tried to uncover more detailed information from Tesla (main office, service dept, sales), but no one has encountered this issue before. Are there any Tesla owners out there with pacemakers? What have been your experiences? Should I worry? Do I need to take preventive measures? I can't believe I'm the first one to face this issue.
     
  2. Chris TX

    Chris TX Active Member

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    There is an EMF thread from way back that covers this. The shielding on modern pacemakers protects them from most everything, and the shielding in the car will not affect a modern pacemaker.

    Best of luck with the pacemaker!
     
  3. trils0n

    trils0n 2013 P85

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    Pretty sure all cars with keyless entry have this warning. I'd probably ask the doctor or the manufacturer of the pacemaker -- they'd probably give you more helpful info than Tesla will.
     
  4. Chris TX

    Chris TX Active Member

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    I did find a warning about the rare earth magnets in the parcel shelf possibly causing problems. That's not a Tesla specific issue, though.
     
  5. tom66

    tom66 Member

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    This warning exists on most products that have an RF transmitter. I think it is a legal liability thing. I am not a lawyer but perhaps the disclaimer absolves them of non-negligent harm claims in the extremely unlikely event that harm arises.

    However there really should be no risk. Modern pacemakers will have been built to handle high power RF transmitters, such as phones and wifi base stations which can transmit in excess of 1W ERP (effective radiated power.) You should check with your doctor/cardiologist but I would expect that there are few if any warnings regarding these devices (the pacemaker will be adequately shielded and designed such as to avoid such interference.) If so then the few milliwatts ERP of keyfob transmitter power should pose no risk at all.
     
  6. Gizmotoy

    Gizmotoy Active Member

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    From researching ICDs, similar in many respects to Pacemakers, there's not much solid information on this, unfortunately. The manufacturers of the medical devices, unsurprisingly, play it very safe but have little understanding of how an EV works. For example, most device manufacturers suggest you remain 3-5 feet from a charging EV. Presumably this is because they're concerned about the fields created in converting wall AC to battery DC. However, riding in an EV is supposedly fine. Here they fail to take into account that the the DC is converted back to AC to propel the vehicle, thus providing the same risks as charging.

    As a practical matter, I suspect you'd be OK plugging in and walking away without hanging around inside the car (especially in the rear seats, which are directly above the inverters) while charging. You might not want to ride in the back, either, if you're being extra cautious.

    Regarding the key fob, you'll find pretty much every RF device you encounter will carry that warning. You'll be instructed by your doctor to use your cell phone on the opposite side of your body, never rest electronic devices on your chest, and things like that. If it's electronic, it probably needs to be at least 1ft. from your pacemaker. Realistically, only AC/DC inverters and devices with RF transmitters are big concerns, but again, the manufacturers are very cautious.

    Best of luck with your medical dilemma. I know it's a lot, but I don't think you need to worry about the car. If you want to chat privately, PM me.
     
  7. SteveS0353

    SteveS0353 Member

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    Congratulations on the new MS70, and welcome to TMC.

    To put my comments into context, I need to disclose that I am a biomedical electronics engineer, who has designed cardiac pacemakers and ICDs for most of my 40 year career. Designers of modern cardiac devices go to great lengths to design, test and qualify the devices in the presence of all sorts of electromagnetic interference. Modern pacemakers are housed in an hermetically sealed titanium enclosure (Faraday cage), with the only way for modulated signals to get into and out of the device via a tiny ceramic feedthrough. The feedthrough itself is also carefully designed to attenuate electromagnetic radiation. It's quite normal to see blanket warnings in manuals and on electrical equipment (even magnetometers at the airport) about pacemaker interference, but the reality these days is that implanted cardiac devices are pretty much immune to even relatively high power radio transmissions. As a precaution, check with your cardiologist or the device manufacturer or both, but personally, I would not be concerned.

    Now rare-earth magnets are another matter. The titanium enclosure (Faraday cage) does not attenuate static magnetic fields. Some pacemakers still have what's called a "magnet mode" where the pacemaker will enter a defined state, usually VOO (ventricular fixed rate) mode where the pacing rate which can be detected by measuring your heart rate, is a function of the remaining battery capacity. Modern pacemakers use radio telemetry to report all sorts of data about the patient and device, but magnet mode still exists. It takes a pretty strong permanent magnet (~5 gauss, 0.5 mTesla) to trigger the mode, and rare-earth magnets at close range could do that.

    All the very best with your new pacemaker, and your brand new Model S, which I'm confident will coexist comfortably.
     
  8. Kandiru

    Kandiru Member

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    Unless she got bad batch from 3 years ago which shorted and ignited spontaneously under the skin she should be OK.

    As others said, the shielding is very good these days, gone are all the microwave and cell phone warnings.
     
  9. Gizmotoy

    Gizmotoy Active Member

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    #9 Gizmotoy, Oct 8, 2015
    Last edited: Oct 8, 2015
    Great info, thanks! You should help train up some support staff. I've spent hours on the websites and phones of both Boston Scientific and Medtronic, and neither have even half that level of information. At least for ICDs, both still inform customers to stay away from microwaves and to never use an induction cooktop. Both recommend keeping any electronic at least a foot from the device, and that if using a cell phone it must be on the right side of your head. Medtronic recommends keeping 5 feet from charging EVs (Boston has no guideline but refused to indicate it was safe), and to refuse to pass through metal detectors or allow metal detection wands to be used.

    Kind of disappointing that what they tell customers is so far from the reality. Liability issues, I guess.

    Edit: Minor correction. Medtronic says you can't be in the EV when charging, not the 5 feet mentioned above. Not sure where I got that.
     
  10. SteveS0353

    SteveS0353 Member

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    Patients with pacemakers and/or ICDs should always be cognizant of their condition and their surroundings. As careful and diligent as device designers are, it's not possible to account for every scenario. Remember that the electromagnetic environment is evolving too. Device OEMs issue warnings out of an abundance of caution, and patients will always be well served to check with their physician and/or the OEM about specific situations. Personally, with knowledge of the field, I would not be concerned about owning and operating an EV if I had a pacemaker.
     
  11. Ocelot

    Ocelot Member

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    Hey Geezer,
    Not much to contribute here, but an anecdote. I have no idea what age qualifies for a 'geezer' these days, but my wife's aunt is 105! Anyhow a few months ago they checked her pacemaker which was inserted when she was (I think)in her 70's). Anyhow it was not working (who knows for how long) and after some debate , put her under GA, and gave her another one. Now she can live another 30 or so years, cardiac-worry-free!
     
  12. Twiddler

    Twiddler Member

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    I am an electrophysiologist, doing my own study on EMI detected on specifically ICDs (which have a larger "antenna" and would be more likely to detect EMI than a pacer). I anticipate that it will be a negative study, and plan to repeat it when we get our Model X. I will certainly post the results once we have concluded - just need to get the medium right :)

    My own review of the literature has revealed no evidence of this thus far - just don't wear your phone in your front chest pocket!
     
  13. Gizmotoy

    Gizmotoy Active Member

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    To give you a hard time, that sounds much more like the usual answers from the device manufacturers :wink:. Manufacturer says ask your physician. Physician says ask the manufacturer. Or you get conflicting answers. Good times.

    Curious to hear your methodology and results. I can't tell if it's an unofficial "study" or a full-blown research endevour :). We'd be lying if we said we weren't even a little bit worried about about the electromagnetic output of an EV interfering with an ICD. I suspect the rear seats have the worst EMI issues given the proximity to the drivetrain/charging components, but haven't measured.
     
  14. Geezer

    Geezer New Member

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    Thanks Chris, I'll check it out!

    - - - Updated - - -

    This is reassuring. Thanks Tom.

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    Great information! Thanks so much for sharing.

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    Wow Steve, what great information. I'm going to share it with my doc. You have reassured me.

    - - - Updated - - -

    A great story! You made my day! My wife and I migrate from FL to Victoria every summer and roost at the Parkside Hotel near the inner harbor. We have a fractional ownership there. Some day, I may drum up enough courage to make the trip in our Model S. All the best.
     
  15. SteveS0353

    SteveS0353 Member

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    I don't think anyone could or can give a blanket guarantee of noninterference in every situation. There are way too many variables and even some unknowns, and the environment is constantly evolving. There were no EVs and high power vehicle charging 40 years ago, but that's a reality today. That's why the OEM's warnings and advice are so conservative - they incorporate enormous safety margins. But after designing implantable medical devices for 40 years, I have very high confidence that a pacemaker patient will be perfectly safe in and around an EV.
     
  16. Gizmotoy

    Gizmotoy Active Member

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    Hell, nobody's asking for any guarantees. There's no guarantees in medicine. Some guidance in place of finger pointing would be nice, though. I'm an engineer, but my wife's a physician and even she is frustrated trying to get anything other than circular answers. We learned more about the devices construction in your one post than all previous discussions with the manufacturers combined.

    Anyway, we figured "EVs kill cardiac patient" would have been a hot headline if there were any actual issues, so we haven't been terribly concerned about it.
     
  17. SteveS0353

    SteveS0353 Member

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    I'm happy to provide informed guidance. I've kept a lot of detailed information on the products I've designed and most all competitive products over the years. Feel free to PM me if you have specific questions.
     
  18. wdolson

    wdolson Active Member

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    My father has had a pacemaker for about 15 years. He doesn't have a Tesla, but he's been around a lot of radio thing, including the keyless entry on his new Ford Fusion. He's never had any problems with interference from anything.

    Early pacemakers had problems with interference from things like microwaves and other devices that produced high frequencies, but they are very well shielded these days. If they weren't people's hearts would stop every time they got a cell phone call, which would be kind of a drag.
     
  19. SteveS0353

    SteveS0353 Member

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    I'm not certain that ICDs are more susceptible to EMI than pacemakers, but the consequence of an adverse event due to interference could be much worse. Unlike ICDs, most pacemaker patients are not dependent on the device for survival, but have the device implanted to correct a slow rhythm which can be debilitating, but rarely fatal. There are pacemaker dependent patients who require the pacemaker to trigger every beat, but the majority of pacemakers overdrive an intrinsic slow rate to help the patient with the normal activities of life. In most cases, if a pacemaker stops for whatever reason, the patient's underlying rhythm will return and while he/she wouldn't necessarily be well, it normally wouldn't lead to anything critical. An ICD is another matter. It's designed to send a large shock to restart sinus rhythm in a fibrillating heart. An interference event could potentially trigger an inappropriately timed and harmful shock.

    While the ICD enclosures are typically larger than pacemakers, the "antenna" for EMI is more likely the endocardial electrode(s) than the can. The worst situation would be a unipolar electrode where the antenna dipole is the electrode tip with reference to the can. Most modern pacemakers and ICDs deploy bipolar electrodes which limit the size of the antenna dipole to a few millimeters (tip and ring active areas at the end of the electrode inside the heart). That geometry makes any EMI mostly a common-mode signal which is essentially not "seen" by the pacemaker/ICD, and what small differential-mode signal is "seen" is attenuated by the front-end filter. Of course, there are very sophisticated signal processing algorithms operating on the detected signal further minimizing any risk. But the electrode configuration and implant geometry plays a large part in ensuring that the induced interference signal is small to begin with.
     
  20. Twiddler

    Twiddler Member

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    Hot off the presses - I was finally able to create a device medium capable of detecting artificial sources of EMI such that testing could take place in my vehicle. I wanted to do a P90D as well (as one kind TMCer offered) but the medium also served as an excellent petri dish. May repeat in the future with an antibiotic-impregnated solution. The following abstract has been submitted to the 2016 Heart Rhythm Society Scientific Sessions.



    ABSTRACT TITLE: Shockingly safe: an in vitro evaluation of ICDs for potential electromagnetic interference within the Tesla Model S.

    AUTHORS:
    Matthew R. Evans, MD1; Brent Gattis1; Javier E. Banchs, MD, FACC, FHRS1; David L. Hayes, MD,FACC, FHRS2
    1 Section of Clinical Cardiac Electrophysiology; Baylor Scott and White, Temple Memorial Hospital, 2401 South 31st Street, Temple, TX 76508
    2 Division of Cardiovascular Diseases; Mayo Clinic, 200 First St. SW, Rochester, MN 55905


    INTRODUCTION:
    Electromagnetic interference (EMI) is a recognized cause of inappropriate implantable cardioverter-defibrillator (ICD) shocks. With the development of large-capacity, rapidly charging battery electric vehicles, concern has grown regarding its safety for patients with ICDs. Prior studies on hybrid vehicles have been negative for clinically-significant EMI. This study is the first to evaluate for evidence of EMI within the largest-capacity electric vehicle on the market, the Tesla Model S.

    METHODS:
    Three of the major device manufacturers, St. Jude Medical, Medtronic, and Boston Scientific, donated ICDs and leads (DF-1 and DF-2, single and dual coil, integrated and true bipolar) for the study. The devices were inserted between two layers of gelatin comprised of 0.8% saline in water (Figure) and sensing was performed in bipolar and unipolar configurations. A single chamber pacemaker and associated lead was also placed on the medium and set to pace at VOO during the study to serve as a background signal. All devices functioned appropriately within the medium. The medium was tested using DC and AC sources; corresponding EMI was successfully detected on the study devices (Figure 1). The devices were placed in the study vehicle, a 2013 Tesla Model S with a 60 kWh battery and single on-board charger. The vehicle was turned on, off and driven at speeds from 1 to 90 miles per hour for a period of at least 60 minutes, and battery of tests was performed with the devices placed in the front trunk, front passenger seat, rear passenger seat, and rear trunk (testing protocol available upon request). The devices were also placed within twelve inches of charging cables when charging at 40 Amps, 220 Volts and when supercharging at 300 Amps, 300 Volts. All devices were interrogated to evaluate for EMI detection during the period of testing.

    RESULTS:
    No EMI was detected in any of the test positions during any test protocols, including testing performed while charging using the on-board charger and supercharging.

    CONCLUSION:
    Data from this in vitro study suggest relative safety from EMI in patients with ICDs. Further testing should be performed in vivo and with different battery configurations to validate these results.


    Figure 1.
    Study devices submerged in conductive gelatin for testing within the test vehicle. The top portion of the figure represents pacing artifact from the VOO pacemaker (bottom right of the container) which served as a background signal source for the ICDs. The right of the strip shows artificial EMI, produced to ensure the devices’ ability to detect.
    Final figure 1.jpg
     

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