Magnetic Resonance Imaging and Radiation Exposure in Patients with Cardiovascular Implantable Electronic Devices
Key Points
Key Points
- MRI generates static and gradient magnetic fields as well as RF energy. The potential interactions between CIEDs and electromagnetic interference from MRI include the following:
- Magnetic field-induced force and torque due to ferromagnetic materials: CIED generator movement is extremely unlikely due to confinement in the subcutaneous tissues.
- Leads do not contain any significant ferromagnetic materials to cause movement in a magnetic field.
- Gradient magnetic field-induced electrical current: Gradient magnetic fields can induce current in conductive wires within the field that could lead to myocardial capture and potentially lead to atrial or ventricular arrhythmias.
- Heating and tissue damage: RF fields can lead to nonconditional CIED component heating and subsequent thermal damage to the surrounding tissue (functional ablation). Changes in sensing or capture thresholds can occur as a result of tissue damage near lead electrodes.
- Effects on reed switch activity: The reed switch is a feature that permits programming of the device by placement of a magnet. Magnetic fields might therefore affect the reed switch activity of a nonconditional CIED, leading to asynchronous pacing and inhibition of tachycardia therapies.
- Electrical reset: High-energy electromagnetic interference (EMI) can lead to electrical or power-on-reset, a backup demand mode, wherein pacing might be inhibited and tachyarrhythmia therapy activated.
- Power-on-reset parameters vary by vendor and type of CIED (See Tables 1 and 2), and can include reset of pacing polarity to unipolar.
- Inhibition of pacing function due to oversensing of MRI-generated signals or pacing at an output below threshold (bipolar or unipolar) in a pacemaker (PM)-dependent patient might occur in the setting of power-on-reset and must be recognized to prevent catastrophic consequences.
- Additionally, battery status can be affected, particularly for CIEDs that are near an elective replacement interval (ERI), which could result in unreliable function.
- Inappropriate function and therapies: EMI from RF energy pulses or rapidly changing magnetic field gradients might cause oversensing that can lead to inappropriate inhibition of demand pacing and possibly asystole in a pacing-dependent patient, or induction of therapies such as inappropriate shocks in a patient with an implantable cardioverter defibrillator (ICD). Other inappropriate tracking or programming changes can occur.
- Magnetic field-induced force and torque due to ferromagnetic materials: CIED generator movement is extremely unlikely due to confinement in the subcutaneous tissues.
- These effects are influenced by various factors, including magnet field strength, RF power, position of the patient and the CIED within the MRI bore, CIED characteristics, and the size of the patient.
Table 1. Programmed Parameters for PMs During Power-On Reset Mode
| Manufacturer | Pacing mode | Pacing output | Pacing polarity | Sensitivity | Magnet1 response |
|---|---|---|---|---|---|
| BIOTRONIK | VVI 70 bpm | 4.8 V @ 1.0 ms | Unipolar | 2.5 mV | Yes |
| Boston Scientific2 | VVI 65 bpm | 5.0 V @1.0 ms | Bipolar | 1.5 mV | No |
| Medtronic | VVI 65 bpm | 5.0 V @ 0.4 ms | Bipolar | 2.8 mV | Yes |
| St. Jude Medical | VVI 67.5 bpm | 4.0 V @ 0.6 ms3 | Unipolar | 2.0 mV | No |
| ELA-Sorin | VVI 70 bpm | 5.0 V @ 0.5 ms | Unipolar | 2.2 mV | No |
2 Boston Scientific CRT-P devices differ in pacing output (5 V @ 0.5 ms) and pacing polarity (right ventricle lead is unipolar and left ventricle lead paces from left ventricle to pulse generator).
3 St. Jude Medical Accent/Anthem and Frontier II models deliver 5 V @ 0.6 ms.
Table 2. Programmed Parameters for ICDs During Power-On Reset Mode
| Manufacturer | Rate cutoff | Detection criteria | Sensitivity | Energy | Pacing mode | Pacing output |
|---|---|---|---|---|---|---|
| BIOTRONIK | 150 bpm | 8/12 | 0.8 mV | 40 J × 8 | VVI 70 bpm | 7.5 V @ 1.5 ms1 |
| Boston Scientific | 165 bpm | 8/10 | 0.25 mV | 41 J × 5 | VVI 72.5 bpm | 5.0 V @ 1.0 ms |
| Medtronic | 188 bpm | 18/24 | 0.3 mV | 35 J × 6 | VVI 65 bpm | 6.0 V @ 1.5 ms |
| St. Jude Medical2 | 146 bpm | 12 | 0.3 mV | 36 J × 63 | VVI 60 bpm | 5.0 V @ 0.5 ms |
| ELA-Sorin | 190 bpm | 6/8 | 0.4 mV | 42 J × 44 | VVI 60 bpm | 5.0 V @ 0.35 ms |
| All devices will respond to magnet application by temporarily disabling tachyarrhythmia detection. Pacing polarity for all devices is bipolar with the exception of Boston Scientific, which paces in a unipolar configuration. Energy values listed for Medtronic and St. Jude Medical represent energy delivered. The remaining represent energy charged. | ||||||
2 The St. Jude Medical Current and Promote family of devices revert to an autosense sensitivity setting, pace at VVI 67.5 beats per minute (bpm) with pacing outputs of 5.0 V @ 0.6 ms.
3 The St. Jude Medical Epic and Epic II family of devices delivers 30 J × 6.
4 ELA-Sorin LivaNova Ovatio family of devices: 34 J × 4.
Device Parameters
Device Param...
....S. Food and Drug Administration (FDA)-Appro...
...initions of CIED Systems in Relation to MRIHavin...
.... Recommendations and Protocol for the Mana...
...l devices should be considered MR c...
...ing in a patient with an MR conditio...
...ecommended for patients with an MR conditional...
...commended for patients with an MR co...
...citative efforts and emergency treatmen...
...ended for patients with an MR conditional syst...
It is reasonable to perform an MR scan on...
Management of Patients with a CIED Referred for MRI
...ent of Patients with a CIED Referred for MRI...
...Recommendations for the Decision to Pe...
...easonable for patients with an MR nonconditiona...
...able to perform an MR scan immediately...
...ents with an MR nonconditional CIED, it i...
...mmendations for the Management of Patients...
...is recommended for the patient with an...
...defibrillator/monitor (with external p...
...mended that continuous MR conditional ECG and pul...
...mmended that personnel with the skill to perform...
...th an MR nonconditional CIED who a...
For patients with an MR nonconditi...
It is recommended that for the patient with...
...yarrhythmia detections for patients with an ICD sh...
...responsible physician who is accountable for ov...
...ommended that ECG and pulse oximet...
...resuscitative efforts and emergency tre...
...tient with an MR nonconditional CIED who is not...
...le to program patients with an MR noncondition...
...e 1. Management Algorit...
.... Checklist for MRI Safety in the Setting of Imp...
...e 8. Implantable Loop Recorder...
...mmended that prior to MRI scanning pati...
...of MR conditional ILRs should be performed wit...
.... Employee Safety...
...recommended that the MR suite has a cl...
...Recommendations for the Management...
...recommended that patients with a CIED un...
...asonable to exclude the device from the fie...
...onable to monitor patients who have...
Management of Patients with a CIED Undergoing CT Imaging
...atients with a CIED Undergoing CT Imaging...
...condary Neutron-Producing Radiation in Various Com...
...le 12. Recommendations and Protocol for...
...tiation of radiation treatment, a complete...
...ducing treatment is preferred over neutron...
...rm weekly complete CIED evaluations...
...lete CIED evaluation should be performed at...
...ntinuous visual and voice contact is...
...location is recommended if its current lo...
...ght be reasonable to perform a complete C...
...ocation is NOT recommended for devices re...
Management of Patients with a CIED Undergoing Radiation Therapy
...anagement of Patients with a CIED Undergoin...
.... Checklist for Performance of Radi...
...igure 4. CIED Management for Radiatio...