Complete loss of ICD programmability after magnetic resonance imaging

Implantable Defibrillator System Shock Function, Mortality, and Cause of Death After Magnetic Resonance Imaging

BACKGROUND

Studies have shown that magnetic resonance imaging (MRI) does not have clinically important effects on the device parameters of non-MRI-conditional implantable cardioverter-defibrillators (ICDs). However, data on non-MRI-conditional ICD detection and treatment of arrhythmias after MRI are limited.

OBJECTIVE

To examine if non-MRI-conditional ICDs have preserved shock function of arrhythmias after MRI.

DESIGN

Prospective cohort study. (ClinicalTrials.gov: NCT01130896).

SETTING

1 center in the United States.

PATIENTS

629 patients with non-MRI-conditional ICDs enrolled consecutively between February 2003 and January 2015.

INTERVENTIONS

813 total MRI examinations at a magnetic field strength of 1.5 Tesla using a prespecified safety protocol.

MEASUREMENTS

Implantable cardioverter-defibrillator interrogations were collected after MRI. Clinical outcomes included arrhythmia detection and treatment, generator or lead exchanges, adverse events, and death.

RESULTS

During a median follow-up of 2.2 years from MRI to latest available ICD interrogation before generator or lead exchange in 536 patients, 4177 arrhythmia episodes were detected, and 97 patients received ICD shocks. Sixty-one patients (10% of total) had 130 spontaneous ventricular tachycardia or fibrillation events terminated by ICD shocks. A total of 210 patients (33% of total) are known to have died (median, 1.7 years from MRI to death); 3 had cardiac arrhythmia deaths where shocks were indicated without direct evidence of device dysfunction.

LIMITATIONS

Data were acquired at a single center and may not be generalizable to other clinical settings and MRI facilities. Implantable cardioverter-defibrillator interrogations were not available for a subset of patients; adjudication of cause of death relied solely on death certificate data in a subset.

CONCLUSION

Non-MRI-conditional ICDs appropriately treated detected tachyarrhythmias after MRI. No serious adverse effects on device function were reported after MRI.

PRIMARY FUNDING SOURCE

Johns Hopkins University and National Institutes of Health.

An operational approach to the execution of MR examinations in patients with CIED

In the context of the increasing spread of cardiac active implantable heart devices (CIEDs) in the population and of the wide diagnostic/therapeutic utility of magnetic resonance (MRI) examinations, the goal of this paper is to provide the experience of the Santa Maria Nuova Hospital of the USL Tuscany Center in Florence and to report an organizational proposal to perform, in the hospital settings, MRI examinations on patients carrying CIED. This report is intended to show the operational choices of a Radiology Department which organizes this activity in accordance with the new Italian regulatory framework in the field of safety of MR sites (Ministero della Salute in Decreto Ministeriale 10 agosto 2018 Determinazione degli standard di sicurezza e impiego per le apparecchiature a risonanza magnetica, 2018).

Practice Advisory for the Perioperative Management of Patients with Cardiac Implantable Electronic Devices: Pacemakers and Implantable Cardioverter–Defibrillators 2020

This practice advisory updates the “Practice Advisory for the Perioperative Management of Patients with Cardiac Implantable Electronic Devices: Pacemakers and Implantable Cardioverter–Defibrillators: An Updated Report by the American Society of Anesthesiologists Task Force on Perioperative Management of Patients with Cardiac Implantable Electronic Devices,” adopted by the American Society of Anesthesiologists in 2010 and published in 2011. This updated advisory is intended for use by anesthesiologists and all other individuals who deliver or who are responsible for anesthesia care. The update may also serve as a resource for other physicians and healthcare professionals who manage patients with cardiac implantable electronic devices.

Supplemental Digital Content is available in the text.

MRI of patients with implanted cardiac devices

Cardiac implanted electronic devices (CIEDs) have historically been regarded as a contraindication for performing magnetic resonance imaging (MRI), limiting the availability of this exam for large numbers of patients who may have otherwise benefited from the unique diagnostic capabilities of MRI. Interactions between CIEDs and the magnetic field associated with MRI systems have been documented, and include potential effects on CIED function, lead heating, and force/torque on the generator. Several device manufacturers have developed "MR-Conditional" CIEDs with specific hardware and software design changes to optimize the device for the MR environment. However, a substantial body of evidence has been accumulating that suggests that MRI may be safely performed in patients with either conditional or nonconditional CIEDs. Institutional policies and procedures, including preexam screening and assessment by skilled electrophysiology personnel and intraexam monitoring, allow MRI to be safely performed in CIED patients, as evidenced by at least two, large multicenter prospective studies and multiple smaller, single-institution studies. Cross-departmental collaboration and a robust safety infrastructure at sites that perform MRI should allow for the safe imaging of CIED patients who have a clinical indication for the study, regardless of the conditionality status of the device.

LEVEL OF EVIDENCE

5 Technical Efficacy: Stage 5 J. Magn. Reson. Imaging 2018;47:595-603.

Practice advisory on anesthetic care for magnetic resonance imaging: an updated report by the american society of anesthesiologists task force on anesthetic care for magnetic resonance imaging

The American Society of Anesthesiologists Committee on Standards and Practice Parameters and the Task Force on Anesthetic Care for Magnetic Resonance Imaging presents an updated report of the Practice Advisory on Anesthetic Care for Magnetic Resonance Imaging.

Supplemental Digital Content is available in the text.

Magnetic resonance imaging safety in pacemaker and implantable cardioverter defibrillator patients: how far have we come?

Magnetic resonance imaging (MRI) has long been regarded a general contraindication in patients with cardiovascular implanted electronic devices such as cardiac pacemakers or cardioverter defibrillators (ICDs) due to the risk of severe complications and even deaths caused by interactions of the magnetic resonance (MR) surrounding and the electric devices. Over the last decade, a better understanding of the underlying mechanisms responsible for such potentially life-threatening complications as well as technical advances have allowed an increasing number of pacemaker and ICD patients to safely undergo MRI. This review lists the key findings from basic research and clinical trials over the last 20 years, and discusses the impact on current day clinical practice. With ‘MR-conditional’ devices being the new standard of care, MRI in pacemaker and ICD patients has been adopted to clinical routine today. However, specific precautions and specifications of these devices should be carefully followed if possible, to avoid patient risks which might appear with new MR technology and further increasing indications and patient numbers.

MRI-conditional pacemakers: current perspectives

Use of both magnetic resonance imaging (MRI) and pacing devices has undergone remarkable growth in recent years, and it is estimated that the majority of patients with pacemakers will need an MRI during their lifetime. These investigations will generally be denied due to the potentially dangerous interactions between cardiac devices and the magnetic fields and radio frequency energy used in MRI. Despite the increasing reports of uneventful scanning in selected patients with conventional pacemakers under close surveillance, MRI is still contraindicated in those circumstances and cannot be considered a routine procedure. These limitations prompted a series of modifications in generator and lead engineering, designed to minimize interactions that could compromise device function and patient safety. The resulting MRI-conditional pacemakers were first introduced in 2008 and the clinical experience gathered so far supports their safety in the MRI environment if certain conditions are fulfilled. With this technology, new questions and controversies arise regarding patient selection, clinical impact, and cost-effectiveness. In this review, we discuss the potential risks of MRI in patients with electronic cardiac devices and present updated information regarding the features of MRI-conditional pacemakers and the clinical experience with currently available models. Finally, we provide some guidance on how to scan patients who have these devices and discuss future directions in the field.

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

Advances in cardiac device technology have led to the first generation of magnetic resonance imaging (MRI) conditional devices, providing more diagnostic imaging options for patients with these devices, but also new controversies. Prior studies of pacemakers in patients undergoing MRI procedures have provided groundwork for design improvements. Factors related to magnetic field interactions and transfer of electromagnetic energy led to specific design changes. Ferromagnetic content was minimized. Reed switches were modified. Leads were redesigned to reduce induced currents/heating. Circuitry filters and shielding were implemented to impede or limit the transfer of certain unwanted electromagnetic effects. Prospective multicenter clinical trials to assess the safety and efficacy of the first generation of MR conditional cardiac pacemakers demonstrated no significant alterations in pacing parameters compared to controls. There were no reported complications through the one month visit including no arrhythmias, electrical reset, inhibition of generator output, or adverse sensations. The safe implementation of these new technologies requires an understanding of the well-defined patient and MR system conditions. Although scanning a patient with an MR conditional device following the strictly defined patient and MR system conditions appears straightforward, issues related to patients with pre-existing devices remain complex. Until MR conditional devices are the routine platform for all of these devices, there will still be challenging decisions regarding imaging patients with pre-existing devices where MRI is required to diagnose and manage a potentially life threatening or serious scenario. A range of other devices including ICDs, biventricular devices, and implantable physiologic monitors as well as guidance of medical procedures using MRI technology will require further biomedical device design changes and testing. The development and implementation of cardiac MR conditional devices will continue to require the expertise and collaboration of multiple disciplines and will need to prove safety, effectiveness, and cost effectiveness in patient care.

[Magnetic resonance imaging in patients with pacemakers and implantable cardioverter-defibrillators: a systematic review]

The presence of a pacemaker or an implantable cardioverter-defibrillator was historically considered a contraindication to magnetic resonance imaging (MRI), due to the risks for both patient and device: reed-switch closure responsible for asynchronous pacing, inhibition of pacing, rapid ventricular pacing, heating on the lead tip or even device displacement... However, many recent studies demonstrate that if MRI is crucial for the management of the patient, it can be performed under specific monitoring and scanning conditions and after device reprogramming. The growing implication of device constructors in constructing a MRI safety device will perhaps extend in the future the indications of this imaging modality in implanted patients.

Cardiac magnetic resonance assessment of mechanical dyssynchrony

PURPOSE OF REVIEW

Echocardiographic techniques have played a major role in the assessment of mechanical dyssynchrony and the selection of patients for cardiac resynchronization therapy. The accuracy and reliability of such measures, however, have recently been placed under great scrutiny. This has shifted interest to cardiovascular magnetic resonance as an alternative method to assess myocardial dyssynchrony but these methods are relatively underdeveloped and not used widely clinically. Accordingly, the purpose of this review is to highlight existing and emerging CMR acquisition methods for quantifying dyssynchrony as well as the potential role of CMR to improve patient selection for CRT.

RECENT FINDINGS

CMR has a number of advantages over current echocardiographic methods for the assessment of myocardial dyssynchrony including quantitative assessment of circumferential strain and myocardial scar burden and distribution. Recent studies also demonstrate the ability to perform CMR in patients with CRT devices.

SUMMARY

CMR assessment of myocardial dyssynchrony is a logical alternative to echocardiographic based methods that provides highly quantitative and reproducible data sets of function and scar that are predictive of CRT response. The future ability to perform CMR imaging in patients pre-CRT and post-CRT may for the first time allow full characterization of CRT response.

Application of a clinical magnet over implantable cardioverter defibrillators: is it safe and useful?

The growing number of implantable cardioverter defibrillator (ICD) implants mean that a high number of patients carrying these devices are attended by physicians. In an attempt to simplify their management, articles have been published on the safety of applying magnets to the ICD in order to avoid the administration of shocks during surgery. However, performance of these procedures without the supervision of expert personnel can be accompanied by serious and potentially fatal complications. We report a case where the use of a clinic magnet over an ICD caused it to switch to "end of life" in the battery indicator and lose some antitachycardia therapies.

Issues and design solutions associated with performing MRI scans on patients with active implantable medical devices

Magnetic Resonance Imaging (MRI) has become one of medicine's most important diagnostic tools. However, due to patient safety concerns, MRI is contraindicated by both device and MRI equipment manufacturers for patients with active implanted medical devices (AIMDs). The primary concern is overheating of implanted leadwires due to currents induced from the powerful RF fields of the MRI scanner. In pacemaker patients, heating of myocardial tissue has caused increase in pacemaker capture threshold and in some cases complete loss of capture (inability to pace). Permanent damage to an implantable cardioverter defibrillator and at least one patient death and another with severe burns along the wires of deep brain electrodes have also been reported. The authors, with pacemaker leadwires placed in a "worse case" MRI scan condition, have measured distal tip leadwire temperatures of up to 57 degrees C (more than sufficient to cause tissue damage). Another risk is localized myocardial ablation which could result in changes in the action potential vector during atrial/ventricular contraction. However, in contrast to reports of problems, there have been several recent anecdotal reports of MRI scans being safely performed on non-pacemaker dependent patients under highly controlled conditions. Proper diagnosis, treatment and management of a number of life threatening diseases such as cancer, neurological and brain disorders are made possible by MRI. Accordingly, the physician, with informed patient consent, must sometimes ignore the legal contraindications, weigh the risk factors, and go ahead and perform an MRI on an AIMD patient. This paper quantifies the attendant risks of performing MRI on AIMD patients and discusses means of mitigating certain hazards such as leadwire overheating including the performance a new leadwire distal tip resonant bandstop filter chip (MRI Chip) which presents a high impedance at the MRI pulsed RF frequency.

MRI in patients with cardiac devices

Given the advances of MRI and cardiovascular technology, it is becoming increasingly likely that a patient with a cardiovascular device will be a candidate for an MRI procedure. However, many cardiac devices are currently considered to be contraindicated in the MR environment. This may prove to be a significant public health problem as many patients in need of MRI are denied the procedure because of the presence of a cardiovascular device. However, research studies have shown that with proper precautions and technique patients with cardiac devices can undergo successful MRI safely on the current platforms.

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

BACKGROUND

Magnetic resonance imaging (MRI) is an important diagnostic modality currently unavailable for millions of patients because of the presence of implantable cardiac devices. We sought to evaluate the diagnostic utility and safety of noncardiac and cardiac MRI at 1.5T using a protocol that incorporates device selection and programming and limits the estimated specific absorption rate of MRI sequences.

METHODS AND RESULTS

Patients with no imaging alternative and with devices shown to be MRI safe by in vitro phantom and in vivo animal testing were enrolled. Of 55 patients who underwent 68 MRI studies, 31 had a pacemaker, and 24 had an implantable defibrillator. Pacing mode was changed to "asynchronous" for pacemaker-dependent patients and to "demand" for others. Magnet response and tachyarrhythmia functions were disabled. Blood pressure, ECG, oximetry, and symptoms were monitored. Efforts were made to limit the system-estimated whole-body average specific absorption rate to 2.0 W/kg (successful in >99% of sequences) while maintaining the diagnostic capability of MRI. No episodes of inappropriate inhibition or activation of pacing were observed. There were no significant differences between baseline and immediate or long-term (median 99 days after MRI) sensing amplitudes, lead impedances, or pacing thresholds. Diagnostic questions were answered in 100% of nonthoracic and 93% of thoracic studies. Clinical findings included diagnosis of vascular abnormalities (9 patients), diagnosis or staging of malignancy (9 patients), and assessment of cardiac viability (13 patients).

CONCLUSIONS

Given appropriate precautions, noncardiac and cardiac MRI can potentially be safely performed in patients with selected implantable pacemaker and defibrillator systems.

Safe scanning, but frequent artifacts mimicking bradycardia and tachycardia during magnetic resonance imaging (MRI) in patients with an implantable loop recorder (ILR)

BACKGROUND

Patients with implantable devices are generally not permitted to undergo magnetic resonance imaging (MRI) because of potentially deleterious interactions. Little has been reported regarding the safety and effects of MRI scanning of patients with implantable loop recorders (ILRs). We evaluated the safety of scanning patients with ILRs and the output of the ILR after undergoing MRI.

METHODS

Ten patients underwent 11 MRI scanning events. All patients had Reveal Plus (Medtronic, Minneapolis, MN) ILRs. Seven cranial, two lumbar-spine, one shoulder, and one knee MRI were performed. All of the MRIs were performed with the understanding that the patient had an ILR. In each patient, the ILR was cleared moments before the scan and the integrity of the signal and time date stamp were verified. The devices were reinterrogated immediately after MRI in 10 patients and two days post MR scanning in one patient. Each patient was questioned post MRI regarding any symptoms experienced during the scan.

RESULTS

Both tachy and bradyarrhythmias appeared as artifacts as a result of ILR exposure to MRI. Post MRI, none of the ILRs showed diminished signal integrity, altered programmed parameters, diminished battery status, inability to communicate or be reprogrammed. No sensations of tugging or warmth at the implant site were noted.

CONCLUSION

MRI was performed in ILR patients without harm to the patient or permanent damage to the ILR. MRI scanning of the Reveal appears safe. Artifact mimicking an arrhythmia was common, however, and must be excluded in any ILR patient undergoing MRI to avoid mistakenly attributing a syncopal episode, or palpitations to the artifacts produced from MRI exposure.

Outcome of magnetic resonance imaging (MRI) in selected patients with implantable cardioverter defibrillators (ICDs)

OBJECTIVE

To determine if simple strategies used to safely scan pacemaker patients could be applied to implantable cardioverter defibrillator (ICD), patients undergoing MRI allowing ICD patients to undergo MRI as well.

INTERVENTIONS

Screening, reprogramming, and monitoring strategies were used to facilitate MRI.

RESULTS

Seven patients underwent eight MRI scans at 1.5 T. Post-MRI, all devices demonstrated no change in pacing, sensing, impedances, charge times, or battery status. The patient undergoing a lumbar spine scan experienced a "power-on-reset" of his ICD without permanent impairment of his device.

CONCLUSION

Scanning of ICD patients might be performed if appropriate reprogramming and monitoring is implemented.