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Table 2 MRI Patient and Scanner Conditions for Clinically Released MR Conditional Systems in the United States or the European Community.

From: Magnetic resonance imaging in patients with cardiac pacemakers: era of "MR Conditional" designs

System

Medtronic EnRhythm MRIâ„¢ SureScanâ„¢ Pacing System

St. Jude Medicalâ„¢ MR Conditional Pacing System

Biotronik ProMRIâ„¢ MR Conditional Pacing System

Approval

United State (FDA appoval)

European Community (CE approval)

European Community (CE approval)

European Community (CE approval)

Studies

Wilcoff et al. [81]

Forleo et al. [82]

Advisa MRI Study [83]. (In process)

Accent MRI Study [145]. (In process)

 

Implant site

Left or right pectoral region

Left or right pectoral region

Chest area.

Patient's height at least 1.4 meters

Limitations related to other devices/leads

No active or abandoned medical devices, leads, lead extenders or adaptors

No abandoned cardiac hardware including leads, lead extenders, or lead adaptors

No other pacemakers or ICDs, leads no longer in use, lead adapters, lead extension

Implant timing prior to MRI

At least six weeks

Stable pacing capture threshold values

At least 6 weeks.

Acceptable lead parameters for MRI

Capture thresholds of ≤ 2.0 V at a pulse width of 0.4 ms

Impedance of ≥ 200 and ≤ 1500 Ohms

No diaphragmatic pacing at 5.0 V at a pulse width of 1.0 ms

Capture threshold values of ≤ 2.5 V at 0.5. ms pulse width

Lead impedance measurements within the programmed lead impedance limits

No diaphragmatic stimulation at a pacing output of 5.0 V or 7.5 V and at a pulse width of 1.0 ms if device will be programmed to an asynchronous pacing mode when MRI Settings are enabled

Capture threshold ≤ 2.0 V at 0.4 ms pulse width

Lead impedance is between 200 and 1500 Ohms •

Battery charging status: at least 30%

Programming for MRI

MR conditional programming modes

MR conditional programming modes

MR conditional programming modes

Device Identifiers

Pulse generator radiopaque marking with a unique symbol and three letter code

Unique radiopaque lead helix design

A radio-opaque MRI symbol is present on all implanted St. Jude Medicalâ„¢ MR Conditional pacing system components

Radiopaque MR Conditional lead marker

Pulse generator radiopaque marking.

No lead radiopaque identifier

Scanner

1.5 Tesla cylindrical bore MR system

1.5 Tesla horizontal closed bore MR system

1.5 Tesla cylindrical bore MR system

Landmark isocenter of RF coil

United States: Superior to C1 or inferior to T12

Ensura MRIâ„¢ SureScanâ„¢ Pacing System and Advisa DR MRIâ„¢ SureScanâ„¢ pacemaker labeling has no restrictions on chest scans outside the United States

Contraindication to use of local transmit-only coils or local transmit and receive coils placed directly over the pacing system

Maximum allowed positioning mark for the isocenter starting from the foot at the hip bone level. and maximum allowed positioning mark for the isocenter from the top of the skull at the level of the eyes).

Patient Positioning

Contraindication to lateral decubitus patient positioning

Must not be positioned on side

Dorsal position only.

Scanner Mode

Scanner in' the normal operating mode (defined as the mode of operation of the MR system in which none of the outputs have a value that cause physiological stress to patients)

Scanner in the normal operating mode or First Level Controlled operating mode

The overall MR scanning time accumulated from the imaging times as displayed by the MRI scanner must not exceed 30 minutes

The total accumulated length of examination for the pacing system must be below 10 hours

Radiofrequency Energy

Maximum gradient slew rate ≤ 200 T/m/s per axis

Whole body specific absorption rate (SAR) levels ≤ 2 W/kg

Head SAR ≤ 3.2 W/kg

Maximum gradient slew rate ≤ 200 T/m/s per axis

Whole body specific absorption rate (SAR) ≤ 4.0 W/kg

Head SAR ≤ 3.2 W/kg

Maximum gradient slew rate ≤ 200 T/m/s per axis

Whole body specific absorption rate (SAR) ≤ 2.0 W/kg

Head SAR ≤ 3.2 W/kg