Auckland City Hospital Cardiac Physiology MRI procedures - Cardiac Implantable Electronic Devices (CIED) and procedures for On-Label and Off-Label ...

Auckland City Hospital Cardiac
 Physiology MRI procedures

Cardiac Implantable Electronic Devices (CIED)
 and procedures for On-Label and Off-Label
                MRI scanning

LF, 60 year-old male
Previous history of DVTs, on life-long warfarin.

Jan 07: Presented with extremely unusual episodes of hiccups associated with severe
   vagal symptoms, nausea and a collapse with documented asystole, requiring
   CPR.

Brain MRI: reported as NAD

8.1.07: Pacemaker inserted by DH

Mid – Feb: represents with progressive quadriplegia, eventually requiring ventilation
   on DCC.

CT scan: not helpful, no obvious cerebral mass. Possible abnormality in brain stem.

MR scan recommended.

(1)

Current ACH Pacemaker Clinic check list:

n   Check List at the time of receiving referral:

     □Review current manufacturer specific guidelines
     □ Pacemaker and Leads are MRI conditional as described by the manufacturer
     □ System has been implanted more than 6 weeks
     □ Device is not close to RRT
     □ Device implanted in the pectoral region
     □ No additional active cardiac implantable devices are present
     □ Abandoned or additional leads or wires are not present
     □ No Lead extenders or adapters are present
     □ Leads are electrically intact (impedance within lead specific range)
     □ Threshold

ACH Pacemaker Clinic: On Label MRI
    Conditional Pacemaker Check List at time of
                     scan:
n   □ Confirm referral check list is correct
n   □ Pre procedure pacemaker check to be performed
n   □ Leads are electrically intact
n   □ Threshold

Off-Label MRI scanning of CIED’s: Considerations

n   The use of MR imaging in CIEDs that are not MR conditional is
    considered contraindicated by cardiac device manufacturers and
    regulatory agencies such as Medsafe and the FDA. However several
    small series and one large series (2) have demonstrated that this
    practice may be safe with a cautious and systematic approach.

n   There are several important concerns about CIEDs in the MRI scanning
    environment; unintentional cardiac stimulation which can trigger
    dangerous arrhythmias, behaviour of the reed switch, EMI inhibition of
    necessary pacing in dependant patients, “power on reset” behaviour,
    and most importantly heating of the pacing leads which cause
    unintentional “ablation” of the lead-tissue interface effecting capture
    threshold and sensing.

n   It is essential to understand that almost all studies of off label and on
    label imaging (with MR conditional pacemakers) of patients with CIEDs
    have used 1.5 Tesla scanners, and that many newer MRI scanners are
    3 Tesla.

Proposed HRNZ guidelines for off-label MRI scanning:

n   There must be a consensus of opinion between the managing clinical team/clinician, the imaging team/Radiologist
    and the CIED team/Cardiologist/Cardiac Electrophysiologist that there is a compelling clinical indication for MR
    imaging with no other imaging modality that is equivalent to MR imaging.

n   The patient must sign an informed consent sheet that includes the fact the imaging is off label, and that there is a
    very small chance of catastrophic device failure and death.

n   The CEID team must be present during the scan, including the immediate availability of a Cardiologist/Cardiac
    Electrophysiologist (?EP Fellow)

n   There must be continual monitoring of the patients with voice communication, ECG monitoring and pulse oximetry
    (the latter is essential as EMI can interfere with ECG recordings, but pulse oximetry (optical trace) is not affected
    by EMI)

n   Full resuscitation capabilities must be kept immediately outside the MRI environment including transcutaneous
    pacing defibrillators. These are physically dangerous in the magnet, and capacitors (including ICD/external
    defibrillator capacitors) will not charge to defibrillate.

n   If there is a problem the scan must be immediately stopped and the patient removed from the MR environment for
    treatment

n   In pacemaker dependent patients there must be a clear pre-determined plan of how to deal with the unlikely event
    of loss of capture (i.e. where to take the patient emergently for transvenous temporary pacing whilst the patient is
    transcutaneously pacing)

n   Scanning should take place in a 1.5 Tesla scanner

n   The most common problem in the scanner is “power on reset” factory setting mode where pacing reverts to an
    inhibited mode (this can be catastrophic if not recognised in a dependant patient) and ICD VT therapies are turned
    with resultant unintentional ATP (shocks are unlikely as the capacitor will not charge)

Absolute Contra-indications for MRI scans:

n   Legacy devices, pacemaker generator pre 1999,
    ICD generator pre 2001
n   Leads < 6 weeks old
n   Epicardial leads
n   Abandoned leads
n   Patients with ICDs who are pacemaker
    dependent (unless there is the ability to program
    temporary asynchronous pacing)

Additional considerations for Off-Label scanning at
                       ACH:

n   Pacemaker dependant patients contra-indicated.
n   No lead extenders or adapters are present
n   Program the lead outputs to sub-threshold values
n   Program pacing mode to OFF or OVO if possible

Case study: ICD Off-Label MRI scan

n   NG, 59 yo female
n   Presented to ED after being stuck in bath for 4 hours. Viral type illness,
    weakness, back pain, rigors.
n   Previous medical history: ICD in situ for DICM, previous CABG, type II
    diabetic, COPD, smoker.
n   Started on antibiotics with initial improvement
n   Day 2, patient got sicker. Possible diagnosis on spinal abscess as back pain
    severe, radiating down to knees.
n   Chest x-ray showed pulmonary oedema. Lumbar puncture NAD, CT spine
    NAD but images were sub-optimal. Referred for MRI scan of spine.
n   Consultant note in patient file ”After careful deliberation and consultation
    with multiple services, we feel the next step is for MRI spine to occur
    despite the risks this entails”

MRI Scan performed:

n   Consent form included direct reference to ICD malfunction and possible
    death.
n   The ICD was programmed off, patient monitored with ECG and pulse ox,
    EP fellow present in MRI suite.
n   Scan performed but terminated early due to patient distress and cyanosis.
n   Findings: no epidural collection or spinal cord compression.
n   Presumed sepsis syndrome, antibiotics continued.
n   Patient recovered slowly, discharged on day 21.
n   Normal ICD function.

References:

n   (1) Nazarian S et al, Clinical Utility and Safety of a Protocol for
    Noncardiac and Cardiac Magnetic Resonance Imaging of Patients with
    Permanent Pacemakers and Implantable-Cardioverter Defibrillators at 1.5
    tesla; Circulation. 2006; 114 1277-1284
n   (2) Nazarian et al. A prospective evaluation of a protocol for Magnetic
    Resonance Imaging of patients with implanted cardiac devices. Ann
    Intern Med 2011;155:415-424.

Auckland City Hospital Pacemaker Clinic:

n   Contact details:
    q   Office hours: 09 630 9923
    q   After hours: 367 000, ask for “on call
        Pacemaker service”
    q   Email Paceclin@adhb.govt.nz