J. Rod Gimbel: Crowdsourcing a Consumer Safety Issue

The following is a guest post by J. Rod Gimbel, MD, a cardiac electrophysiologist from Knoxville, TN who has written extensively on the issue of electronic surveillance systems and electromagnetic interference with cardiac implantable electronic devices:

I’d like to express my appreciation for allowing me to guest post in this space.

This is about crowdsourcing a consumer safety issue; specifically the public safety of consumers who happen to have CIEDs (cardiac implantable electronic devices) such as pacemakers or implantable defibrillators (ICD). Nearly 2 million such consumers (patients) have CIEDs in the U.S. alone. As you know, these devices are susceptible to EMI (electromagnetic interference). Simply put, the lead(s) act like antennas and can pick up stray EMI from any number of sources and cause the device to malfunction by either withholding therapy (no pacing or ICD rescue therapy) or through delivery of inappropriate therapy (delivering pacing output or shocks where none is needed). Either situation can be life threatening.

One source of EMI that can affect a CIED patient is electronic article surveillance system (EAS). Such systems are widely used by retailers (ref) to deter and prevent store theft, a problem commonly referred to as “shrinkage”.

About 8 years ago, an ICD patient that I was caring for received inappropriate shocks from his ICD after being near an EAS system located in a big box retailer. A colleague of mine related a similar situation where a pacemaker dependent patient reported syncope in the proximity of an EAS system after her pacemaker inhibited in response to the EMI from the EAS system. These were two disturbing, potentially life threatening events. In hopes of raising awareness of this serious problem (EAS-CIED interaction), we generated a manuscript detailing the events that was published in 2007 in the Mayo Clinic Proceedings. Notably, the New York Times picked up the story. Others have published similar unfortunate misadventures between patients and EAS systems.

Several common sense recommendations have been made in this area; recommendations that preserve a retailer’s right to deter and reduce theft (a legitimate concern), but still protect CIED patients from adverse interactions with EAS systems. For instance, after receiving reports of several adverse events caused by EAS systems the Food and Drug Administration (FDA) issued a “Safety Communication” and noted:

• Be aware that EAS systems may be hidden/camouflaged in entrances and exits where they are not readily visible in many commercial establishments.


• Do not stay near the EAS system or metal detector longer than is necessary and do not lean against the system.

Beyond this, we and others also suggested:

• Retailers should not "camouflage" the EAS pedestals with advertising as this may prevent customers with devices from recognizing the threat and may actually draw device patients toward the EAS pedestal.


• Retailers should not place goods and services near the EAS systems that effectively encourage the patients to violate the "don't linger, don't lean" dictum that physicians tell patients who have devices.

It seems entirely reasonable to suggest a shared responsibility between medical device professionals, device patients, retailers, and EAS system manufacturers. It was hoped EAS manufactures and retailers would do their part and embrace these simple recommendations and help make retail spaces safe for those with implantable devices. Unfortunately, this does not seem to always be the case.

Figure 1: Bench to "relax" placed adjacent to a camouflaged EAS pedestal at big box retailer.

Figure 2: Chair to "relax" placed adjacent to EAS pedestal while patient waits for prescription to be filled at retail pharmacy store.

Figure 3: Complimentary coffee station where device patients might linger placed adjacent to EAS pedestal at big box retailer

These pictures were taken in the last several months around the country. Clearly, the juxtaposition of EAS systems and consumer areas may undermine the dictum “don’t linger, don’t lean” and leave device patients in harm’s way. Who then, is responsible for the safety of device patients in this situation?

Finally, perhaps in an attempt to thwart a determined and “informed shoplifter” who may employ several methods that might undermine the effectiveness of EAS systems, “there are also concerns that some installations are purposefully configured to exceed the rated specifications of the manufacturer, thereby exceeding tested and certified magnetic field levels.” This may increase further the risk of adverse reactions experienced by device patients when near EAS systems.

Now for the crowdsourcing part:

A presentation on this topic (CIED-EAS interactions) to an extra governmental regulatory group helping set standards for the device industry is to be given soon. This presentation will be to a number of interested parties including representatives of the EAS manufactures, device manufactures, and the FDA. As noted above, the “event rate” of these interactions is rather low, but as has been suggested significant under-reporting may obscure the true significance of the problem. It is surely recognize that not everyone has the time or inclination to write up adverse events for publication or inclusion in a database. Perhaps, some events go entirely unrecognized for what they really are, being passed off as “Oh, Mom passed out at the store today, but she’s OK now”.

With your help a strong presentation and case can be made emphasizing CIED-EAS interactions are an important public safety issue. Your voice and concerns can be heard. First off, send pictures where you see EAS systems placed in a manner that might endanger a device patient (like the ones shown above). Cell phone pictures are just fine. Second, if you are a health care provider or patient, please send any “events” that you may have experienced describing an adverse interaction between an EAS system and pacemakers and or ICDs. Please post the items here or send items of interest to J. Rod Gimbel, MD (gimbeljr@gmail.com). Your response is of course appreciated and in confidence and any presentation of the material provided will be anonymized. Upon completion of the presentation, a link will be posted here.

This is an important effort that Rod is undertaking on behalf of patients with CIEDs. I hope patients and health care providers will come forward with examples of EAS systems or EAS interference in their locales to assist him in this important consumer safety effort.

-Wes

The Challenges of Medical Device Follow-up

With the explosion of medical devices to treat various medical ailments in medicine, we have seen significant improvements in quality and quantity of life. An underappreciated consequence of all of these electronic device therapies, however, has been the manpower and expertise required to manage these implanted electronic medical devices long-term.

Problems with electromagnetic interference (EMI) with medical devices are real. Innovations in medicine have come from various portions of the electromagnetic spectrum including analog and digital wireless technology, diagnostic and therapeutic radiation therapy and magnetic resonance imaging. The effects of these technologies on implanted electronic medical devices can vary and specialty physicians, ancillary health care providers, and medical device manufacturers expend significant man-hours managing these potential interference sources and their affects on devices without a single prospective randomized trial to guide us. The sheer number of devices and the many ways that EMI can interfere with these complex devices makes constructing an all-inclusive trial with sufficient number of "events" to compare difficult or nearly impossible. As a result, most of our management recommendations and hospital policies in this regard have been based from literature case reports or personal experience and expertise.

To date, recommendations for minimizing EMI with cardiac implantable electronic devices has been sorely lacking, so the new recommendations published (1.3 Meg pdf) recently by the Heart Rhythm Society (HRS) in conjunction with American Society of Anesthesiologists (ASA) should serve as a helpful guide for physicians involved in the management of these devices. It would be well beyond the scope of this blog to include all of the pre-procedural, intra-procedural and post-procedural recommendations made by this document. But there are some other limitations to these recommendations that warrant mention.

First, there are a multitude of makes and models of pacemaker and implantable cardiac defibrillator devices which are covered by this document. The document is fairly inclusive regarding today's technology. New models forthcoming, however, are not specifically covered by this document (how can they be?) so the challenges keeping these recommendations current will remain a challenge.

Secondly, these recommendations do not cover the management of devices during magnetic resonance imaging, an evolving innovation in these devices, but no less important for patient management in these procedures.

Third, this document covers only implantable electronic cardiac devices. Nerve stimulators, brain stimulators, insulin pumps and a whole host of other implanted electronic devices still remain outside the purview of these recommendations, yet pose similar challenges to patient management, both from a technical expertise AND manpower-need standpoint. The challenges of not only electromagnetic interference, but also device-device interference remain and still need to be considered clinically.

Finally, the recommendations were made in conjunction with the expertise of industry and physician experts. While these recommendations appear to have been made for patients benefit, the real need for the medical device industry to limit their manpower needs for peri-procedural device checks should not go unnoticed. Much of the newer innovations of home monitoring has been forwarded in part to address these simultaneous patient and industry needs. Still, it goes without saying that doctors should remember that any local hospital recommendations developed on the basis of these guidelines should always put the needs of the patient before those of the medical device industry or hospital administration.

-Wes

Reference: The Heart Rhythm Society (HRS)/American Society of Anesthesiologists (ASA) Expert Consensus Statement on the Perioperative Management of Patients with Implantable Defibrillators, Pacemakers and Arrhythmia Monitors: Facilities and Patient Management.

Could a Bra Interact With a Pacemaker or Defibrillator?

The comment was posted on this blog earlier:

"I was reading one of your old posts about magnets and I was wondering if a magnetic front closure on a bra would be a problem? There's a warning on the label but I know part of that is just due to liability. What about the new Victoria Secret bra that has a magnet clasp on the front? If the magnet hits right in between the breasts would it be close enough to the device that it could interfere? Also does having a magnet that close change the settings or turn off a defibrillator/pacemaker early? I'm sure most doctors would say just wear another bra but this bra in particular is very comfy! I've tried it on but not worn it for extended periods of time. Luckily this is one of the only major complaints I've had about having heart disease and a medtronic device at such a young age."

First, let me say thank you for asking this question: who knew research could be so, er, entertaining! Second, this question reinforces why medical blogging is so great: you learn something new every day.

Now, as I slap myself back to a bit more professional stance, I'll summarize by saying I think you'll be okay to use such a bra with some precautions. Given the picture and the clasp's location, this bra is more likely to interfere with the pacemaker of the partner you hug rather than yourself, provided your pacemaker was implanted over 3 centimeters from the magnetic clasp. Since most pacemakers and defibrillators are implanted just below the collar bone, the chance of the magenetic clasp to interfere with your device is remote. From my earlier post:

Pacemakers and defibrillators contain a small "reed switch" that is sensitive to magnetic fields that allows patients and their doctors an opportunity to affect their device to perform specific functions outlined below.

In the case of pacemakers, the activated reed switch tells the pacemaker to pace, irrespective of the person's underlying rhythm, at a specific rate (determined by the manufacturer of the pacemaker). When the rate changes, this tells doctors how much voltage is left in the person's pacemaker, and uses the paced rate to act like a battery meter, telling doctors when the pacemaker battery voltage is getting low. It does NOT inhibit pacemaker output. (Oh, there will be some wise guy that says that pacing that does not synchronize with one's heart rhythm could land in the "vulnerable period" of the cardiac cycle and induce an abnormal rhythm (and yes, that can occur), but magnet checks are done tens of thousands of times a day in the US and I have never heard of someone dying from this with conventional pacemakers).

In the case of a defibrillator (that treats abnormally fast and slow heart rhythms), the reed switch acts slightly differently. Again, a magnet over the person's defibrillator does NOT inhibit pacing at all. In the case of a defibrillator, a magnet over the device that is powerful enough to trip its reed switch will suspend detection of rapid heart rhythms while the magnet is over the device. In the case of this article, this will only happen if a magnet is held within three centimeters of the device. That's only 1.5 inches, folks. In other words, one of these fridge magnets or pieces of jewelry would have to be held virtually right over the device to have any effect. Certainly, if the person had the unfortunate luck that a rapid heart rhythm occurs when a magnet of sufficient strength is over the device, then the device would not detect this rapid heart rhythm and it could be fatal. But the odds of that happening are very, very low.

-Wes

Reference:
Wolber T, Ryf S, Binggeli C, Holzmeister J, Brunckhorst C, Luechinger R, Duru F. Potential interference of small neodymium magnets with cardiac pacemakers and implantable cardioverter-defibrillators. Heart Rhythm. 2007 Jan;4(1):1-4. Epub 2006 Sep 16.

More EP Woo: The Hill Gets Duped

Politics and medicine shouldn't mix.

To prove the point, The Hill recently ran a story reviewing a study that suggested that cell phones may cause heart irregularities.

Little did they know that the "study" is nothing more than a re-hash of the author's concocted "electrohypersensitivity syndrome" that I de-bunked earlier in November, 2009. Seems these guys can't get enough of their fear-mongering tactics.

Note that the current 23 October 2010 press release claiming "new research" that was "just published" in the obscure print-only Italian journal European Journal of Oncology uses the exact same data graphs they used in their earlier 'work' in November, 2009.

Geez.

-Wes

Addendum: "Electrohypersensivity syndrome" link fixed.

Pacemakers and Defibrillators in the Dental Chair

Powerful magnets that can interfere with pacemakers and defibrillators can pop up in the strangest places, like dental chair headrests:

A few months ago, Boston Scientific, one of the major manufacturers of pacemakers/ICDs, added a new caution to their contraindications for dental patients. They warn that if a patient has a pacemaker/ICD, and the dental chair has a magnetic headrest with strength over 10 gauss, the patient should NOT sit in the chair.

The company states: “Some dental chairs contain magnets located in the headrest. If the pacemaker or defibrillator is programmed not to respond to a magnet, patients may sit in these chairs. If the implanted device is programmed to respond to a magnet and the magnet power is less than 10 gauss, patients may sit in these chairs. If the magnet power is greater than or equal to 10 gauss, patients should not sit in these chairs as the device function/programming may be affected.”

Allow me to explain. Magnet strength is measured in gauss units. The farther the distance from the magnet, the weaker the gauss reading, which means a weaker magnetic field. The magnets on dental chairs currently in use contain magnets with strength over 400 gauss. (Strengths vary slightly among manufacturers.) Therefore, sitting in the typical dental chair with a pacemaker/ICD, one would have to be five to six inches away from the magnet to be safe. Sometimes, however, dental professionals have trouble accessing certain parts of the mouth, and we ask patients to move up in the headrest, which is closer to the magnet. When we get too close to the magnet, the magnetic effect increases, and therefore, so does the potential for complications.

The linked article above does a good job giving a balanced review of this topic, so take a minute to read the whole thing.

-Wes

Reference: Boston Scientific's "Dental Equipment and Implantable Pacemakers and Defibrillators" white paper dated 2 Feb 2009.

Pacemakers, Defibrillators, and Hybrid Cars

With the interest and popularity of going "green" with hybrid cars (even with a select few of my fellow physician-bloggers) I thought it would be worthwhile to share a few tidbits about the potential for electromagenetic interference between hybrids and pacemakers or defibrillators. (Heck, maybe they'll need this info when they get older and have their pacer installed...)

There's been some recent reports of people returning their Toyota Prius or Camry Hybrid, Lexus GS450h, or other newer hybrid cars due to fears over interference with these cars' "smart keys" (which detect when the key is within three feet of the car) and pacemakers or automatic defibrillators. It seems these cars' smart key antennas transmit at frequencies of between 119 and 135 kHz with a relatively low power. Still, because of the wonders of physics, if a pacemaker or defibrillator were sufficiently close to one of these antennas, then there could be the potential for interference. But is there enough of a risk to trade back in a car?

Once again, it seems more devices are being developed out there than the pacemaker and defibrillator device manufacturers can test sufficiently to assure that nary an issue exists with outside electromagnetic interference. One only needs to look at the recently popularized iPod interference issues or the disclaimers on the Nintendo's Wii gaming system to see how far the hysteria can go.

So before more scary press releases occur, I called some pretty smart "engi-nerd" types from the manufacturers (Note: I use the term "nerd" here with respect, since I are one) to find out a bit more about the potential for excitement in people driving hybrids with pacemakers or defibrillators. Here's the basic gist:

Medtronic: Hybrid Cars: Cars that are powered, at any one time, with either batteries, gasoline or both.

"Gasoline engine: Maintain a 12" (30 cm) distance from the components of the ignition system of the gasoline engine and the Pacemaker or ICD. If closer than 10" (30 cm), there is the potential for Pacemaker reversion or inhibition and for ICD shock.

Electric power components: The DC/AC current used to power the electric motors and the permanent magnets associated with the motor operation can affect the Pacemaker or ICD. Maintain a 24" (60cm) distance between the electric motor and the implanted device. If the device is closer than 24" (60cm), there is the potential for Pacemaker reversion or magnet rate operation or disabling of ICD detection circuit or ICD shock."

St. Jude Medical:

"Cardiac pacemakers are electronic devices with sensing circuits designed to detect small electrical signals from the heart. Pacemakers may detect extraneous electrical signals from sources other than the heart and incorrectly interpret these signals as heart activity. Inhibition of the pacemaker, resulting in no output pulse to the patient's heart or reversion to asynchronous pacing may result. At this time we have no reports of large-scale electrical motors or generators affecting our pacemakers. However, this does not mean there is a total absence of affects related to electric motors of several hundred horsepower. Extraneous radiated noise from large-scale electrical motors will not cause damage to your pacemaker. If large-scale electrical motors do affect the pacemaker, inhibition or reversion to asynchronous pacing may potentially occur. Some patients can tolerate reversion to asynchronous pacing or some inhibition of their pacemaker. Any problems caused by radiated interference will end when the electrical interference ends or the patient leaves the immediate area. The risk of working with large-scale electrical motors may be reduced to an
acceptable level by observing proper techniques. Working on the motors with the power “OFF” will avoid electrical interference. In the power generating plants I have visited, the large motors and generators have been grounded and shielded which minimized the radiation of electrical noise."

Boston Scientific:

They recommend a 9 inch (22 cm) clearance from a smart key to any of the antennaes on hybrid cars. This more conservative distance was recommended by the Japan Association of Medical Equipment Industries' (JAMEI)(a la, Toyota) rather than Boston Scientific. It seems they are still in the process of their own testing. Boston Scientific's recommendations regarding smart keys and their devices, with diagrams of where the transmitting and receiving antennaes are housed, can be found on Boston Scientific's website (pdf file).

In summary with smart keys, there seems to be a consensus that the risk of interference with pacemakers or defibrillators is low, especially if the smart key is not left near the device (i.e., in a shirt pocket). Most felt the power of these "keyless" devices was sufficiently low (like the iPod, Wii, or cell phones) to limit concerns over their interference with pacemakers or defibrillators provided some common-sense distance precautions were maintained.

Regarding interference with the electric motor components of hybrid cars, two manufacturers have recommendations regarding being too near the engine and that operating a hybrid car should be quite safe, as long as the operator with a pacemaker or defibrillator does not try to become the mechanic for their own car.

-Wes

Pacemakers and iPods Revisited

Finally, another study confirms the safety of iPods and pacemakers.

For this study, Bassen tested a second-generation iPod Nano, a second-generation iPod shuffle, a fifth-generation iPod Video with a 30-gigabyte hard drive, and a standard iPod with a 15-gigabyte hard drive and dock connector.


For all of them, data taken at 0.5 and 1.0 cm from the case showed a field of 0.2 micro-Tesla or less, with a highly localized 100 kilohertz sinusoidal signal.


The fields existed only in an area of about 1 cm2 and were not measurable at distances greater then 1 cm from the case, Bassen said.


He also found no measurable fields near the earphone cable, except at the earphone itself.

Hopefully, the American Heart Association will pick up on this story and print a retraction to their earlier fear-mongering quiz.

-Wes

h/t: MedPage Today.

The AHA and Medical Fear Mongering

If you have a pacemaker or implantable cardiac defibrillator, slipping an iPod into your shirt pocket, or walking past anti-theft equipment at the mall, could make your device go haywire - true or false?

This is the second question of a quiz (available online) from the August 2007 Heart Insight magazine, an official publication of the American Heart Association (AHA) published quarterly by Wolters Kluwer Health, a division if Lippincott Willliams & Wilkins publishers. It is a slick, glossy publication and was being offered for free to our patients:


So today, a patient left this for me on my desk:



It is the "answer" to the above question that appeared in their journal, circled by a patient with the question penciled beside it, "Is this true?"

Now on the surface, such a quiz seems innocent enough. After all, it's meant to inform. But look what it has done to one of my patients. THe patient is asking, Could this happen to me?" This person is concerned. Scared. Fearful.

This how our own AHA wants to get their message across, I guess.

But when one really looks at the information provided in the answer to the question, we find the real answer in amongst the confusing array of sound bites:

"Researchers found that MP3 players such as Apple's iPod, interfered with pacemaker function in half of the 83 patients who participated in the study; none of them experienced symptoms."

So there you have it. None of them experienced symptoms and, by the way, none of the patient's devices went "haywire."

Not one.

The supporting study (actually a case report) pertaining to the first part of this answer appeared in the peer-reviewed journal Heart Journal in June 2007. This case study studied the interference of an iPod held within two inches of pacemakers. It found very minor, non-lethal interference (usually undersensing of the patient's intrinsic heart rhythm) in most cases. No patient was harmed. In fact, no patient was tested with the device in their shirt pocket. From the article:

In our patient, oversensing did not result in pacemaker inhibition or noise reversion; it was evidenced only by pacemaker interrogation that showed high atrial or ventricular rates on rate histograms. This may lead the physician to conclude that the patient had experienced atrial fibrillation (Figure 4) or ventricular tachycardia (Figure 2) and result in unnecessary antiarrhythmic drug therapy or electrophysiologic investigations. These high rates also may be misinterpreted as suggesting loose set screws or intermittent lead fracture and may lead to unnecessary interventions. Interference caused by iPods appears to be reproducible from day to day, but whether repeated applications have a cumulative effect on rate histograms is not known.

We performed testing by applying the iPod approximately 2 inches above the pacemaker. This may appear to be somewhat artificial but is, in fact, quite realistic because iPod devices often are carried on an armband or in a shirt pocket during use. If the iPod is placed in an ipsilateral shirt pocket, it certainly may be close enough to cause interference. Furthermore, electromagnetic signals emitted by handheld devices probably are of low power, and the strength of the signal falls dramatically over distance. However, because iPod devices may be carried close to the pacemaker, there may be a potential for clinically significant interference.

Also, the article did not study ANYTHING about the interference of electronic surveillance systems in malls with pacemakers or defibrillators. But rather than be true to their readers (our patients), it seems the AHA had to add the bit more fear-factor by citing rare case studies (see references 1 and 2 below) where patients had to go to ER's for "malfunctions of the heart devices," even though other studies, while acknowledging that interference can occur, actually demonstrated the safety of patients walking through electronic surveillance systems with defibrillators. Once again, no devices went "haywire" but rather responded appropriately to the noise detected by the device.

So why does our own American Heart Association, in its new "official" publication, condone such fear mongering of our patients, even when their own website claims minimal risk to patients in these settings. What benefit does this serve? Is this medical marketing tactic in our patients' best interest? Shouldn't the AHA provide more journalistic oversight than appears on the Today Show?

Or is the sensationalist content more important to their egos?

-Wes

References:
(1)Peter A. Santucci, M.D., Janet Haw, R.N., Richard G. Trohman, M.D., and Sergio L. Pinski, M.D. Interference with an Implantable Defibrillator by an Electronic Antitheft-Surveillance Device New Engl J Med 1998; 339:1371-1374.

(2) Interactions between Cardiac Pacemakers and Antishoplifting Security Systems. New Engl J Med Nov 5, 1998: 339: 1394-1395.

(3) Harthorne, J. W., Barach, P., Baum, E., Santucci, P. A., Pinski, S. L., Trohman, R. G., McIvor, M. E., Sridhar, S. (1999). Implantable Defibrillators, Pacemakers, and Electronic Antitheft Devices. New Engl J Med 340: 1117-1119. A rebuttal to the first two case reports above.

(4) William J. Groh, MD; Scott A. Boschee, BS; Erica D. Engelstein, MD; William M. Miles, MD; M. Erick Burton, MD; Peter R. Foster, MD; Barry J. Crevey, MD; Douglas P. Zipes, MD Interactions Between Electronic Article Surveillance Systems and Implantable Cardioverter-Defibrillators Circulation 1999; 100: 387-392.

(5) Mehul B. Patel, MD, Jay P. Thaker, Sujeeth Punnam, MD, Krit Jongnarangsin, MD. Pacemaker interference with an iPod. Heart Rhythm Volume 4, Issue 6: 781-784 (June 2007).