Medtronic Revo Pacemaker (Designed to Permit MRI Scanning)

You see, up until the Revo, pacemakers were considered a very potent contraindication to MRI exams. Interference from the MRI acting on the pacemaker could turn the pacer off, turn it into a fairly benign ‘asynchronous mode’, start pacing your heart as if it were a hummingbird’s at 100′s of beats per minute, burn cardiac muscle, or drain the pacer’s battery precipitating an earlier-than-planned replacement.

Some pacemaker patients could still get MRI exams, but you had to be the right kind of pacemaker patient, with the right kind of pacing device, needing the right kind of MRI on the right kind of scanner. Even then, you ought to have had the cardiologist and a code team (to resuscitate you if the MRI and your pacer decided to not cooperate), plus someone to de-program and re-program your pacer. Even with those protections, some insurance companies simply forbid coverage of MRI exams for any pacemaker patient.

Along comes the Medtronic Revo pacemaker. This is the first FDA-approved biostimulation implant that has been specifically designed, from the ground up, to permit MR examinations (though it won’t be the last). It is not, however, carte blanche for MRI examinations. There are important limitations, or conditions, for its safe use.

There are three designations, each with very specific critera, that an object or medical device can obtain to describe its relative safety in the MR environment, ‘MR Safe’, ‘MR Conditional’, and ‘MR Unsafe’. Given the fact that I just described the Revo as having important limitations, or conditions for safe use, which of these three designations do you think the Revo has earned?

If an object receives the ‘MR Safe’ designation, it means that that object would be safe under any allowable MRI conditions. Field strength? Doesn’t matter. Magnetic spatial gradient? Who cares. Time-varying gradient? No worries, mate. RF deposition? Don’t worry your pretty little old head. In short, to receive the ‘MR Safe’ designation there can not be any restrictions on its use.

So here we are, with a pacemaker that isn’t ‘MR Safe’, but is being touted in nearly every medical media (or mass media with a health reporter) as the “MRI Safe pacemaker”.

[We'll ignore, for this entry, the fact that a company has already copyrighted the phrase "MRI Safe", as well as the fact that this company uses the copyrighted name to describe products that aren't classified as 'MR Safe'.]

For the lay person, my hair-splitting must seem awfully pedantic. The problem is that the technologist who will administer a patient’s MRI exam gets the bulk of the information about the patient’s medical history from the patient, himself. If the patient doesn’t remember the brand-name of the pacemaker (and so many of them seem to forget — or at least fail to disclose — that they even have the device, I think remembering the model and manufacturer is very unlikely), they’re probably likely to remember that this particular one was “MRI safe”. Now the technologist, charged with vetting the patient for MRI safety, is being given misleading information about the safety of scanning that patient.

So, my call to healthcare media and reporters is to please… PLEASE stop calling the Revo the “MRI Safe” pacemaker. Call it what it is, the first pacer designed to allow MRI scanning, or the first MR Conditional pacemaker, or even Medtronic’s towering achievement (which it is).

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Example of a Pacemaker Pulse-Generator Which Could Present Dangerous Contraindications For MRI Exams

The review has been requested by Robert Russo, MD, with Scripps Research Institute. A copy of Dr. Russo’s request can be viewed here.

The public comment period is open through July 28, 2010, and I strongly encourage anyone with questions or concerns about the safety of MR imaging for patients with implanted cardiac devices (Dr. Russo correctly points out that CMS’ restriction fails to speak directly to implanted cardio-defibrillators, or ICD’s) to offer their comments to CMS.

The full explanation of the current restrictions on MR imaging of pacemaker patients (also aneurysm clip patients, and pregnant patients), as well as the instructions for reviewing other public comments or submitting your own, can be found here.

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