MRI Compatible Pacemakers: Medtronic's Grunt Work Gift To Rad Techs!

I got my first experience with MRI compatible pacemakers the other day.  An MRI compatible pacemaker you say?  That's right folks. Engineers at Medtronic have developed the first FDA approved pacemaker that can be used with MRI technology, if certain conditions are met.   The pacemaker procedure note said MRI compatible.   Technically, the FDA calls it MRI conditional because, as stated above, certain conditions must be met to make the MRI experience safe.  Because this technology has the possibility of changing how we manage our paced hospitalist patients, I think it's important to become familiar with it.  So I did a little research on the matter and found some interesting details.

Medtronic's Revo MRI SureScan Pacing System was approved by the FDA on February 8th, 2011.  Here is the FDA approval letter.  Look at all the regulatory requirements necessary to keep this thing on the  market.  It is no wonder these devices cost tens of thousands of dollars.

What are the model numbers of  Revo the MRI SureScan Pacing System FDA?  As per their approval letter:

The Center for Devices and Radiological Health (CDRH) of the Food and Drug Administration (FDA) has completed its review of your premarket approval application (PMA) for the Revo MRI SureScan Pacing System, which consists of the Medtronic Revo MRITM SureScanTM Model RVDRO1 IPG, the Medtronic CapSureFix MRITM SureScanTM 5086MRI lead, and the Revo MRITM Software Application Model SWO18. This system is indicated as follows: The Medtronic Revo MRITM SureScanTM Model RVDRO1 IPG is indicated for use as a system consisting of a Revo MRI SureScan IPG implanted with two CapSure Fix MRFM SureScanTM 5086MRI leads. A complete system is required for use in the MRI environment
The Medtronic Revo MRITM SureScanTM Model RVDRO1 IPG is indicated for multiple rhythm conditions, most of which are consistent with other pacer indications.  You can look at the FDA approval letter above for details.

Is there a special MRI protocol that must be used with this MRI compatible pacemaker?

Yes.  Medtronic has special step-by-step instructions to complete a successful MRI scan.  However, here are some brief details of importance I found most clinically relevant for hospitalists. 
  • MR must be a 1.5T cylindrical bore magnet. The Revo MRI SureScan Pacing System is not approved to use with other magnetic field strengths. Gradient system with maximum gradient slew rate of less than or equal to 200 Tesla per meter per second (T/m/s) must be used. Whole body averaged SAR must be less than or equal to 2W/kg, head averaged SAR less than 3.2W/kg.
  • Must have patient’s Cardiologist approval and order for pacer settings (Attachment C).  Although, apparantely not, see below.
  • The isocenter of the magnetic field will not be positioned between C1-T12.  I'm not sure, but I suppose this means you can't MRI the c-spine or t-spine or anything near them, like the chest. 

Can the MRI Conditional SureScan pacemaker be identified on chest xray?  

Yes.  The Medtronic website says their device contains an  easily identifiable SureScan radiopaque icon on the device and lead that confirms SureScan technology.  Here is a picture from the Medtronic site showing their radiopaque identifiable markers.  As an aside, I could not find these markers on my patient's chest x-ray.
Radiopaque device markers for SureScan. 


Clinically, I think this new device will add a new level of complexity to medical decision making in our hospitalized patients.  Will that 80 year old demented patient with a seizure and a pacemaker know if they have an MRI safe device?  If not, should hospitalists assume all pacers are MRI safe and have all  pacer patients be evaluated by the MRI team for MRI compatibility?

Could a hospitalist be sued by a lawyer who claims their client was harmed because the doctor should have pursued an  MRI because their client had an MRI conditional pacemaker and not knowing that fact was failure to provide standard of care? 

How difficult will it be to obtain in-patient MRIs for our hospitalist patients?   I learned the pacer device will not necessarily have to have cardiologist orders, despite what the company's website says, but could instead be  managed by the radiology team and a pacer representative from the company (that may need several days to a week notification).   In addition, specific information would need to be obtained from the implanting cardiologist's records before the MRI could be performed.    This says to me that in-patient MRIs with these conditional MRI pacemakers isn't a straight forward process for hospitalists.    There could be delays of several days, which would increase length of stays, while the information is gathered and the right people are rounded up to safely administer the MRI with this Revo device.  

It used to be easy.  If the patient had a pacemaker they didn't  get an MRI.  Most of the time, it didn't matter.  Most of the time, our elderly hospitalist patients could be treated medically with a presumptive clinical diagnosis and not doing an   MRI.    Now that MRI compatible pacemakers are going to be mixed with devices that are not compatible, the decision on whether or not the patient can or cannot be scanned has just become relevent for hospitalists and other subspecialty physicians.

If a pacer is present, how long will it take for us to get necessary information to make clinical medical decisions?  Perhaps days?  Will this increase the risk of hospital acquired infections or medication errors at a significant cost?    And once we know, how should we respond?   Should older pacers be removed and these newer devices implanted based on how strongly the hospitalist or neurologist felt an MRI was warranted?  And once a new device is put in, should clinical decisions be made while the patient is sent home for 6 weeks to wait for the pacer implant process to heal before proceeding with an MRI?  What guidelines are there for this risk-benefit analysis.  What complications and additional costs could result from that decision to pursue invasive intervention?  And who's going to pay for it in the ObamaCare era that promises to decimate hospital revenue models.

It's great to know we now have MRI conditional pacemakers.  What effect will they have on clinical practice and what will be their unintended consequences.  What will be their benefit and cost?   I suppose only time will tell. 

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