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MRI-Safe Pacemakers Available In U.S. Hospitals Soon: What It Means For Heart Patients

February 18th, 2011 by Mary Knudson in News, Opinion
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This was the Guest Blog at Scientific American on February 16th, 2011.

New wave of MRI-safe pacemakers set to ship to hospitals

This week Medtronic will begin shipping to hospitals in the United States the first pacemaker approved by the FDA as safe for most MRI scans. For consumers, it is a significant step in what is expected to be a wave of new MRI-compatible implanted cardiac devices.

But this is an example of one technology chasing another and the one being chased, the MRI scanner, is changing and is a step ahead of the new line of pacemakers. The pacemaker approved for U.S. distribution is Medtronic’s first-generation pacemaker with certain limitations, while its second-generation MRI-compatible pacemaker is already in use in Europe where approval for medical devices is not as demanding as it is in the U.S. So let’s check out what this is all about — what it means now for current and future heart patients and where it may be headed.

We are all born with a natural pacemaker that directs our heart to beat 60 to 100 times a minute at rest. The pacemaker is a little mass of muscle fibers the size and shape of an almond known medically as the sinoatrial node located in the right atrium, one of four chambers of the heart. The natural pacemaker can last a lifetime. Or it can become defective. And even if it keeps working normally, some point may not function well along the electrical pathway from the pacemaker to the heart’s ventricles which contract to force blood out to the body.

Millions of people in the world whose hearts beat too fast, too slow, or out of sync because their own pacemaker is not able to do the job right, follow their doctors’ recommendation to get an artificial pacemaker connected to their heart to direct its beating. The battery-run pacemaker in a titanium or titanium alloy case the size of a small cell phone, (why can’t it be the size of an almond?) is implanted in the upper left chest, just under the skin, with one or two insulated wire leads connecting to the heart. It can be programmed to run 24/7 or to only operate when the heart reaches a certain state of irregular beating. Read more »

*This blog post was originally published at HeartSense*

Can A Bra Interact With A Pacemaker Or Defibrillator?

January 8th, 2011 by DrWes in Better Health Network, Health Tips, Humor, Opinion
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This comment [with a specific photo] was posted on my 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 this 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 [medical] 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 three 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. Read more »

*This blog post was originally published at Dr. Wes*