Magnetic Resonance Imaging of Implantable Cardiac Rhythm Devices at 3.0 Tesla

Multimodality imaging in patients with implantable loop recorders: Tips and tricks

An implantable loop recorder (ILR) is a leadless rectangular device used for prolonged electrocardiographic monitoring for up to 3 years. This miniaturized device, inserted subcutaneously, allows clinicians to investigate possible cardiac rhythm disturbances in patients suffering from recurrent unexplained syncope. As the age of the population increases rapidly and the number of ILR patients amplifies, the clinical significance of ILRs is undeniable. Although radioopaque and easily seen on plain chest radiographs and other imaging modalities, ILRs may represent a challenge for clinicians and radiologists to recognize their classic appearance and differentiate them from numerous other cardiac devices. This article aims to summarize current literature on ILRs, their basic function, types, and indications for implantation, but most of all, it aims to familiarize clinicians and radiologists with common imaging features of these devices, safety issues, and artifact-reducing methods. Specifically, this review discusses the typical appearance of ILRs on major diagnostic imaging modalities, including chest X-ray, mammography, ultrasonography, computed tomography, and magnetic resonance imaging (MRI). Furthermore, optimization strategies to mitigate image artifacts and safety issues regarding MRI are discussed.

Joint British Society consensus recommendations for magnetic resonance imaging for patients with cardiac implantable electronic devices

Magnetic Resonance Imaging (MRI) is increasingly a fundamental component of the diagnostic pathway across a range of conditions. Historically, the presence of a cardiac implantable electronic device (CIED) has been a contraindication for MRI, however, development of MR Conditional devices that can be scanned under strict protocols has facilitated the provision of MRI for patients. Additionally, there is growing safety data to support MR scanning in patients with CIEDs that do not have MR safety labelling or with MR Conditional CIEDs where certain conditions are not met, where the clinical justification is robust. This means that almost all patients with cardiac devices should now have the same access to MRI scanning in the National Health Service as the general population. Provision of MRI to patients with CIED, however, remains limited in the UK, with only half of units accepting scan requests even for patients with MR Conditional CIEDs. Service delivery requires specialist equipment and robust protocols to ensure patient safety and facilitate workflows, meanwhile demanding collaboration between healthcare professionals across many disciplines. This document provides consensus recommendations from across the relevant stakeholder professional bodies and patient groups to encourage provision of safe MRI for patients with CIEDs.

Institutional experience report on the target contouring workflow in the radiotherapy department for stereotactic arrhythmia radioablation delivered on conventional linear accelerators

PURPOSE

In stereotactic arrhythmia radioablation (STAR), the target is defined using multiple imaging studies and a multidisciplinary team consisting of electrophysiologist, cardiologist, cardiac radiologist, and radiation oncologist collaborate to identify the target and delineate it on the imaging studies of interest. This report describes the workflow employed in our radiotherapy department to transfer the target identified based on electrophysiology and cardiology imaging to the treatment planning image set.

METHODS

The radiotherapy team was presented with an initial target in cardiac axes orientation, contoured on a wideband late gadolinium-enhanced (WB-LGE) cardiac magnetic resonance (CMR) study, which was subsequently transferred to the computed tomography (CT) scan used for treatment planning-i.e., the average intensity projection (AIP) image set derived from a 4D CT-via an axial CMR image set, using rigid image registration focused on the target area. The cardiac and the respiratory motion of the target were resolved using ciné-CMR and 4D CT imaging studies, respectively.

RESULTS

The workflow was carried out for 6 patients and resulted in an internal target defined in standard anatomical orientation that encompassed the cardiac and the respiratory motion of the initial target.

CONCLUSION

An image registration-based workflow was implemented to render the STAR target on the planning image set in a consistent manner, using commercial software traditionally available for radiation therapy.

Magnetic resonance in patients with cardiovascular devices. SEC-GT CRMTC/SEC-Heart Rhythm Association/SERAM/SEICAT consensus document

Magnetic resonance has become a first-line imaging modality in various clinical scenarios. The number of patients with different cardiovascular devices, including cardiac implantable electronic devices, has increased exponentially. Although there have been reports of risks associated with exposure to magnetic resonance in these patients, the clinical evidence now supports the safety of performing these studies under specific conditions and following recommendations to minimize possible risks. This document was written by the Working Group on Cardiac Magnetic Resonance Imaging and Cardiac Computed Tomography of the Spanish Society of Cardiology (SEC-GT CRMTC), the Heart Rhythm Association of the Spanish Society of Cardiology (SEC-Heart Rhythm Association), the Spanish Society of Medical Radiology (SERAM), and the Spanish Society of Cardiothoracic Imaging (SEICAT). The document reviews the clinical evidence available in this field and establishes a series of recommendations so that patients with cardiovascular devices can safely access this diagnostic tool.

Magnetic resonance in patients with cardiovascular devices. SEC-GT CRMTC/SEC-Heart Rhythm Association/SERAM/SEICAT consensus document

Magnetic resonance has become a first-line imaging modality in various clinical scenarios. The number of patients with different cardiovascular devices, including cardiac implantable electronic devices, has increased exponentially. Although there have been reports of risks associated with exposure to magnetic resonance in these patients, the clinical evidence now supports the safety of performing these studies under specific conditions and following recommendations to minimize possible risks. This document was written by the Working Group on Cardiac Magnetic Resonance Imaging and Cardiac Computed Tomography of the Spanish Society of Cardiology (SEC-GT CRMTC), the Heart Rhythm Association of the Spanish Society of Cardiology (SEC-Heart Rhythm Association), the Spanish Society of Medical Radiology (SERAM), and the Spanish Society of Cardiothoracic Imaging (SEICAT). The document reviews the clinical evidence available in this field and establishes a series of recommendations so that patients with cardiovascular devices can safely access this diagnostic tool.

3 Tesla magnetic resonance imaging in patients with cardiac implantable electronic devices: a single centre experience

AIMS

Three Tesla (T) magnetic resonance imaging (MRI) provides critical imaging information for many conditions. Owing to potential interactions of the magnetic field, it is largely withheld from patients with cardiac implantable electronic devices (CIEDs). Therefore, we assessed the safety of 3T MRI in patients with '3T MRI-conditional' and 'non-3T MRI-conditional' CIEDs.

METHODS AND RESULTS

We performed a retrospective single-centre analysis of clinically indicated 3T MRI examinations in patients with conventional pacemakers, cardiac resynchronization devices, and implanted defibrillators from April 2020 to May 2022. All CIEDs were interrogated and programmed before and after scanning. Adverse events included all-cause death, arrhythmias, loss of capture, inappropriate anti-tachycardia therapies, electrical reset, and lead or generator failure during or shortly after MRI. Changes in signal amplitude and lead impedance were systematically assessed. Statistics included median and interquartile range. A total of 132 MRI examinations were performed on a 3T scanner in 97 patients. Thirty-five examinations were performed in patients with 'non-3T MRI-conditional' CIEDs. Twenty-six scans were performed in pacemaker-dependent patients. No adverse events occurred during or shortly after MRI. P-wave or R-wave reductions ≥ 50 and ≥ 25%, respectively, were noted after three (2.3%) scans, all in patients with '3T MRI-conditional' CIEDs. Pacing and shock impedance changed by ± 30% in one case (0.7%). Battery voltage and stimulation thresholds did not relevantly change after MRI.

CONCLUSION

Pending verification in independent series, our data suggest that clinically indicated MRI scans at 3T field strength should not be withheld from patients with cardiac pacemakers or defibrillators.

Magnetic Resonance Imaging Safety in Patients with Cardiac Implantable Electronic Devices

High strength magnetic and electric fields used in magnetic resonance imaging (MRI) render images with unmatched soft tissue contrast. These imaging attributes have made MRI an increasingly preferred diagnostic tool in many medical conditions. Initially there was substantial concern regarding the safety of performing these imaging studies in patients with cardiac implantable electronic devices (CIEDs), which have the potential to be affected by the intense electric and magnetic fields of the MRI. More recently, there has been increasing evidence that MRI can be performed safely in patients with devices that have not been specifically labelled by regulatory agencies for use in an MRI environment (MRI nonconditional devices), which has allowed the Centers for Medicare and Medicaid Services (CMS) to start providing reimbursement for MRIs of patients with MRI nonconditional devices. For CMS to reimburse scans, a rigorous protocol must be followed, which recognizes that there are still potential adverse effects that can be mitigated by appropriate procedures. In this review we will survey the initial experiences and efforts to understand the magnitude of risk for device malfunction and harm, as well as current efforts to minimize the potential risks of MRI effects on devices and leads (heating, device movement, lead dislodgement, and device malfunction, the latter including inhibition of pacing and generation of arrhythmias).

MR safety considerations for patients undergoing prostate MRI

Over the past decade, there has been a dramatic increase in the number of patients undergoing prostate MRI scans. Patients presenting for prostate MRI are an ageing population and may present with a variety of passive or active implants and devices. These implants and devices can be MR safe or MR conditional or MR unsafe. Patients with certain MR-conditional active implants and devices can safely obtain prostate MRI in a specified MR environment within specific MR imaging parameters. Prostate MRI and PET-MRI in patients with passive implants such as hip prostheses, fiducial markers for SBRT, brachytherapy seeds and prostatectomy bed clips have unique concerns for image optimization that can cause geometric distortion of the diffusion-weighted imaging (DWI) sequence. We discuss strategies to overcome these susceptibility artifacts. Prostate MRI in patients with MR conditional active implants such as cardiac implantable electronic devices (CIED) also require modification of imaging parameters and magnet strength. In this setting, a diagnostic quality prostate MRI can be performed at a lower magnet strength (1.5 T) along with modification of imaging parameters to ensure patient safety. Imaging strategies to minimize susceptibility artifact and decrease the specific absorption rate (SAR) in both settings are described. Knowledge of MR safety considerations and imaging strategies specific to prostate MRI and PET-MRI in patients with implants and devices is essential to ensure diagnostic-quality MR images and patient safety.

3.0 T magnetic resonance imaging scanning on different body regions in patients with pacemakers

PURPOSE

Magnetic resonance imaging (MRI) at 3.0 T is becoming more common, but there is a lack of sufficient evidence on the safety of a 3.0 T scan in patients with pacemakers. This study aimed to investigate the safety and practical concerns of 3.0 T scans for patients with MR-conditional pacemakers.

METHODS

Twenty consecutive patients were enrolled. A standardized protocol was developed by cardiologists, pacemaker engineers, and radiologists. Pacemaker interrogation was performed immediately before and after the scan. Scan-related adverse events were documented, and imaging quality was graded as level 1 to 4 by radiologists.

RESULTS

Twenty-three MRI scans of different body regions (brain = 13, lumbar spine = 4, cervical spine = 2, and heart = 4) were performed, and the average time of a scan was 25 ± 11 min. No significant changes in sensing amplitude (atrial 3.1 ± 1.1 mV vs. 2.9 ± 1.2 mV, P = 0.71; ventricular 9.3 ± 3.5 mV vs. 10.2 ± 3.4 mV, P = 0.46), lead impedances (atrial 647 ± 146 Ω vs. 627 ± 151 Ω, P = 0.7; ventricular: 780 ± 247 Ω vs.711 ± 226 Ω, P = 0.36), or pacing threshold (atrial 0.6 ± 0.2 V/0.4 ms vs. 0.6 ± 0.2 V/0.4 ms, P = 0.71; ventricular 0.7 ± 0.3 V/0.4 ms vs. 0.7 ± 0.2 V/0.4 ms, P = 0.85) were observed pre- and postscan. No adverse events were detected. Image quality review showed grade 1 quality in 16 patients and grade 2 quality in 4 patients with artifacts of pulse generators and leads in cardiac MRI scan and no impact on diagnostic value.

CONCLUSION

Our initial data indicated that 3.0 T scanning might be feasible under a standardized protocol with good diagnostic imaging quality irrespective of body region in patients with MR-conditional pacemakers.

Guideline for Cardiovascular Magnetic Resonance Imaging from the Korean Society of Cardiovascular Imaging-Part 1: Standardized Protocol

Cardiac magnetic resonance (CMR) imaging is widely used in many areas of cardiovascular disease assessment. This is a practical, standard CMR protocol for beginners that is designed to be easy to follow and implement. This protocol guideline is based on previously reported CMR guidelines and includes sequence terminology used by vendors, essential MR physics, imaging planes, field strength considerations, MRI-conditional devices, drugs for stress tests, various CMR modules, and disease/symptom-based protocols based on a survey of cardiologists and various appropriate-use criteria. It will be of considerable help in planning and implementing tests. In addressing CMR usage and creating this protocol guideline, we particularly tried to include useful tips to overcome various practical issues and improve CMR imaging. We hope that this document will continue to standardize and simplify a patient-based approach to clinical CMR and contribute to the promotion of public health.

Cardiac MRI for Patients With Cardiac Implantable Electronic Devices

OBJECTIVE. Patients with cardiac implantable electronic devices (CIEDs) require cardiac MRI (CMRI) for a variety of reasons. The purpose of this study is to review and evaluate the value and safety of CMRI for patients with in situ CIEDs. CONCLUSION. Late gadolinium enhancement CMRI is the reference standard for assessing myocardial viability in patients with ventricular tachycardia before ablation of arrhythmogenic substrates. The use of late gadolinium enhancement CMRI for patients with CIEDs is safe as long as an imaging protocol is in place and precaution measures are taken.

Clinical safety of the ProMRI implantable cardioverter-defibrillator systems during head and lower lumbar magnetic resonance imaging at 3 T: results of the ProMRI 3T ENHANCED Master study

AIMS

There have been no published studies on the safety of magnetic resonance imaging (MRI) at 3 Tesla (3 T) in patients with MRI-conditional implantable cardioverter-defibrillators (ICDs). The aim of this study was to assess clinical safety of the Biotronik ProMRI ICD system during non-diagnostic head and lower lumbar scans under 3 T MRI conditions.

METHODS AND RESULTS

The study enrolled 129 patients at 12 sites in Australia, Singapore, and Europe. Predefined head and lower lumbar MR scans (total duration ≈30 min) were performed in 112 patients. Three primary endpoints were evaluated from the pre-MRI to the 1-month post-MRI visit: (i) freedom from serious adverse device effects (SADEs) related to MRI (hypothesized to be >90%); (ii) pacing threshold invariance for all leads (geometric mean of the patient-wise ratios for 1 month vs. pre-MRI was hypothesized to be <1.07); and (iii) sensing amplitude invariance (geometric mean of the ratios was hypothesized to be >0.993). No MRI-related SADE occurred (SADE-free rate 100%, 95% confidence interval 95.98-100%). Pacing threshold and sensing amplitudes fulfilled the invariance hypotheses with high statistical significance (P < 0.0013). No threshold increase >0.5 V or sensing amplitude decrease by >50% was observed (secondary endpoints). Lead impedances, battery capacity, and detection and treatment of arrhythmias by ICDs were not affected by MRI scans.

CONCLUSION

The head and lower lumbar scans under specific 3 T MRI conditions were safe in the investigated MR-conditional ICD systems. There was no evidence of harm to the patients or any negative influence of the MRI scan on the implanted systems.

Provision of MR imaging for patients with cardiac implantable electronic devices (CIEDs): a single-center experience and national survey

BACKGROUND

Patients with cardiac implantable electronic devices (CIEDs) were traditionally denied access to MR imaging due to safety concerns.

AIMS

The aim of this study was to review a single-center experience of MR imaging at 1.5T of patients with CIEDs and survey national availability of this service.

METHODS

Three hundred thirty-four patients with CIEDs were included in the review. Two hundred nine patients did not progress to MRI due to non MR-conditional CIEDs, retained pacing leads, recent implant insertion, and other patient factors. A record was made of CIED type, number of body parts imaged, numbers of repeat studies and complications. All devices were scanned with cardiology involvement.

RESULTS

One hundred twenty-five patients, 90 males, 35 females, aged 20-91 years progressed to MR imaging. Eighty-six patients had pacemakers, 15 had implantable cardioverter devices (ICDs), and 24 had implantable loop recorders (ILRs). Twenty-one patients had more than one body part scanned. Regions scanned included spine n = 82, joints n = 42, head n = 40, heart n = 8, and abdomen/pelvis n = 13. Twenty-six patients had multiple separate MR studies (range 2-6). Three complications included diaphragmatic stimulation when the device was switched to MR-conditional mode resulting in scan abandonment, device failure post-MRI requiring manufacturer reprogramming, and patient dizziness post reprogramming requiring cardiology review. One cardiac study was non-diagnostic due to artifact from a low left-sided ICD. Imaging of patients with pacemakers is available in 14 of 42 (38%) hospitals with MR units nationally.

CONCLUSION

MR-conditional CIEDs can be safely scanned with diagnostic quality at 1.5T using a protocol involving radiology and cardiology.

[Pacemaker and MRI in clinical practice]

The number of cardiac pacemaker wearers is continuously increasing in Germany as well as worldwide. The probability of indications for a magnetic resonance imaging (MRI) examination during the lifetime is approximately 50-75% for every person. An MRI examination is nowadays possible for pacemaker wearers under certain conditions. Due to the technical developments during the last 10 years certain MRI-conditional pacemakers are available. The recommendations of the German and American medical specialist societies currently allow an MRI examination in patients with conventional pacemakers beyond the approval conditions (off-label use) under prespecified conditions, based on the study data. This article summarizes the information on conditions of use and reprogramming strategies as well as on the study situation for the clinical routine.

State-of-the-art approach towards magnetic resonance imaging of the nervous system structures in patients with cardiac implantable electronic devices

INTRODUCTION

MRI generated forces are the source of potential complications in patients with cardiac implantable electronic devices (CIED). The technological progress, and growing clinical evidence concerning the operation of the contemporary MR non-conditional CIEDs during MRI, have started to significantly change our every-day clinical practice. Nevertheless, a lot of patients who could have an MRI performed safely, still have been refused the examination.

STATE-OF-THE-ART

In many clinical situations, an MRI examination in a patient with a CIED is reasonable, and is linked to a negligible risk of complications if performed under strict precautions. The MagnaSave Registry that evaluated the influence of nonthoracic MRI on the function of MR non-conditional CIEDs, and numerous studies involving thoracic and non-thoracic MRIs in patients with legacy CIEDs, have confirmed the feasibility and safety of such examinations. In this article, practical tips aimed towards improving the safety of MRI in MR conditional and non-conditional CIED patients are largely based on the very recently released (2017) HRS expert consensus statement.

CLINICAL IMPLICATIONS

Clinical data emphasize the necessity of making the MRI more accessible to CIED patients, also in the case of MR non-conditional systems or when the thorax MR imaging is clinically reasonable. This goal should be achieved by increasing the number of centers complying with respective recommendations and applying protocols that would guarantee the highest safety level.

FUTURE DIRECTIONS

Further studies are warranted to assess safety issues related to the main current contraindication to MRI, i.e., the presence of abandoned leads.

Cardiac implanted electronic devices and MRI safety in 2018-the state of play

Traditionally, the presence of cardiac implanted electronic devices (CIEDs) was a contra-indication to magnetic resonance (MR) imaging. Professional groups from around the world are releasing updated guidelines for the imaging of MR-conditional and legacy CIEDs, reflecting increasing evidence that this can be performed safely when strict protocols are followed.

KEY POINTS

• The presence of a pacemaker or automatic implanted cardioverter defibrillator is no longer an absolute contraindication to magnetic resonance imaging. • Strict protocols enable diagnostic quality images to be obtained with minimal risk. • Close collaboration among radiologists, cardiologists and device manufacturer representatives is required.

An eight-year prospective controlled study about the safety and diagnostic value of cardiac and non-cardiac 1.5-T MRI in patients with a conventional pacemaker or a conventional implantable cardioverter defibrillator

OBJECTIVES

To investigate safety and diagnostic value of 1.5-T MRI in carriers of conventional pacemaker (cPM) or conventional implantable defibrillator (cICD).

METHODS

We prospectively compared cPM/cICD-carriers undergoing MRI (study group, SG), excluding those device-dependent or implanted <6 weeks before enrolment or prior to 01/01/2000, with cPM/cICD-carriers undergoing chest x-ray, CT or follow-up (reference group, RG).

RESULTS

142 MRI (55 cardiac) were performed in 120 patients with cPM (n=71) or cICD (n=71). In the RG 98 measurements were performed in 95 patients with cPM (n=40) or cICD (n=58). No adverse events were observed. No MRI prolonged/interrupted. All cPM/cICD were correctly reprogrammed after MRI without malfunctions. One temporary communication failure was observed in one cPM-carrier. Immediately after MRI, 12/14 device interrogation parameters did not change significantly (clinically negligible changes of battery voltage and cICD charging time), without significant variations for SG versus RG. Three-12 months after MRI, 9/11 device interrogation parameters did not change significantly (clinically negligible changes of battery impedance/voltage). Non-significant changes of three markers of myocardial necrosis. Non-cardiac MRI: 82/87 diagnostic without artefacts; 4/87 diagnostic with artefacts; 1/87 partially diagnostic. Cardiac MRI: in cPM-carriers, 14/15 diagnostic with artefacts, 1/15 partially diagnostic; in cICD-carriers, 9/40 diagnostic with artefacts, 22 partially diagnostic, nine non-diagnostic.

CONCLUSIONS

A favourable risk-benefit ratio of 1.5-T MRI in cPM/cICD carriers was reported.

KEY POINTS

• Cooperation between radiologists and cardiac electrophysiologists allowed safe 1.5-T MRI in cPM/cICD-carriers. • No adverse events for 142 MRI in 71 cPM-carriers and 71 cICD-carriers. • Ninety-nine per cent (86/87) of non-cardiac MRI in cPM/cICD-carriers were diagnostic. • All cPM-carrier cardiac MRIs had artefacts, 14 examinations diagnostic, 1 partially diagnostic. • Twenty-three per cent (9/40) of cardiac MRI in cICD-carriers were non-diagnostic.

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.

Safety and utility of magnetic resonance imaging in patients with cardiac implantable electronic devices

BACKGROUND

Off-label magnetic resonance imaging (MRI) for patients with cardiac implantable electrical devices has been limited owing to concerns about safety and unclear diagnostic and prognostic utility.

OBJECTIVE

The purpose of this study was to define major and minor adverse events with off-label MRI scans.

METHODS

We prospectively evaluated patients with non-MRI-conditional cardiac implantable electrical devices referred for MRI scans under a strict clinical protocol. The primary safety outcome was incidence of major adverse events (loss of pacing, inappropriate shock or antitachycardia pacing, need for system revision, or death) or minor adverse events (inappropriate pacing, arrhythmias, power-on-reset events, heating at the generator site, or changes in device parameters at baseline or at 6 months).

RESULTS

A total of 189 MRI scans were performed in 123 patients (63.1% [78] men; median age 70 ± 18.5 years; 56.9% [70] patients with implantable cardioverter-defibrillators; 33.3% [41] pacemaker-dependent patients) predominantly for brain or spinal conditions. A minority of scans (22.7% [43]) were performed for urgent or emergent indications. Major adverse events were rare: 1 patient with loss of pacing, no deaths, or system revisions (overall rate 0.5%; 95% confidence interval 0.01-2.91). Minor adverse events were similarly rare (overall rate 1.6%; 95% confidence interval 0.3-4.6). Nearly all studies (98.4% [186]) were interpretable, while 75.1% [142] were determined to change management according to the prespecified criteria. No clinically significant changes were observed in device parameters acutely after MRI or at 6 months as compared with baseline across all patient and device categories.

CONCLUSION

Off-label MRI scans performed under a strict protocol demonstrated excellent short- and medium-term safety while providing interpretable imaging that frequently influenced clinical care.

Cardiac MRI in patients with complex CHD following primary or secondary implantation of MRI-conditional pacemaker system

OBJECTIVES

In patients with CHD, cardiac MRI is often indicated for functional and anatomical assessment. With the recent introduction of MRI-conditional pacemaker systems, cardiac MRI has become accessible for patients with pacemakers. The present clinical study aims to evaluate safety, susceptibility artefacts, and image reading of cardiac MRI in patients with CHD and MRI-conditional pacemaker systems. Material and methods CHD patients with MRI-conditional pacemaker systems and a clinical need for cardiac MRI were examined with a 1.5-T MRI system. Lead function was tested before and after MRI. Artefacts and image readings were evaluated using a four-point grading scale.

RESULTS

A total of nine patients with CHD (mean age 34.0 years, range 19.5-53.6 years) received a total of 11 cardiac MRI examinations. Owing to clinical indications, seven patients had previously been converted from conventional to MRI-conditional pacemaker systems. All MRI examinations were completed without adverse effects. Device testing immediately after MRI and at follow-up showed no alteration of pacemaker device and lead function. Clinical questions could be addressed and answered in all patients.

CONCLUSION

Cardiac MRI can be performed safely with high certainty of diagnosis in CHD patients with MRI-conditional pacemaker systems. In case of clinically indicated lead and box changing, CHD patients with non-MRI-conditional pacemaker systems should be considered for complete conversion to MRI-conditional systems.

Cardiovascular Magnetic Resonance Imaging in Patients with an Implantable Loop Recorder

BACKGROUND

Implantable loop recorders (ILRs) allow continuous cardiac monitoring for 3-6 years and are a valuable tool for the investigation of syncopal episodes, palpitations, and atrial fibrillations as well as risk stratification after myocardial infarction. Although magnetic resonance imaging (MRI) in patients with ILRs has been shown to be safe, the impact of ILRs on cardiac MRI image quality has not been investigated yet. Thus, we tested the diagnostic value of cardiac MRI in patients with various types of ILRs.

METHODS

Two patients with an ILR and a clinical indication to assess myocardial burden of scarring and fibrosis or stress-induced myocardial ischemia underwent cardiac MRI. Device interrogation was performed prior to, immediately after, and 3 months after cardiac MRI.

RESULTS

The post-MRI follow-ups revealed no change in programmed ILR parameters, sensing fidelity, and battery parameters. However, ILRs caused significant, uninterpretable hyperintensity artifacts in cardiac MRI.

CONCLUSIONS

Further clinical studies are warranted to investigate whether modified MRI techniques are helpful to eliminate imaging artifacts.

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 and implantable cardiac electronic devices

PURPOSE OF REVIEW

To assess the current knowledge about the potential hazard from MRI in patients with devices such as pacemakers and implantable cardioverter defibrillators (ICDs).

RECENT FINDINGS

Most data concern 'MRI unsafe' devices, with only a few studies on 'MRI conditional' devices. No 'MRI safe' cardiac devices are currently available. Studies on 'MRI unsafe' devices tend to be small scale and reflect the experience of individual centres; few provide long-term follow-up data. Many newer devices are approved as 'MRI conditional' based on technical simulations or postmarket surveillance studies. With adequate measures taken before performing an MRI scan, reported complication rates are generally low, but there is a nonnegligible residual risk for power-on reset and lead heating. The presence of abandoned, older leads may affect the propensity for lead heating during MRI with newer devices, including those designated 'MRI conditional'. Very little research has been carried out on the hazard from MRI scans in patients with ICDs, but registry data indicate more events with ICDs than with pacemakers.

SUMMARY

The limited available data indicate a manageable but not negligible MRI-associated hazard in patients with implantable cardiac devices. Further controlled studies and large, independent registries, particularly in Europe, are needed to provide important safety information.

Canadian Heart Rhythm Society and Canadian Association of Radiologists Consensus Statement on Magnetic Resonance Imaging with Cardiac Implantable Electronic Devices

Magnetic resonance imaging (MRI) has historically been considered contraindicated for individuals with cardiac implantable electronic devices (CIEDs) such as pacemakers and implantable defibrillators. Magnetic resonance scanners produce magnetic fields that can interact negatively with the metallic components of CIEDs. However, as CIED technology has advanced, newer MRI conditional devices have been developed that are now in clinical use and these systems have had demonstrated safety in the MRI environment. Despite the supportive data of such CIED systems, physicians remain reluctant to perform MRI scanning of conditional devices. This joint statement by the Canadian Heart Rhythm Society and the Canadian Association of Radiologists describes a collaborative process by which CIED specialists and clinics can work with radiology departments and specialists to safely perform MRI in patients with MRI conditional CIED systems. The steps required for patient and scanning preparation and the roles and responsibilities of the CIED and radiology departments are outlined. We also briefly outline the risks and a process by which patients with nonconditional CIEDs might also receive MRI in highly specialized centres. This document supports MRI in patients with MRI conditional CIEDs and offers recommendations on how this can be implemented safely and effectively.

Immediate and 12 months follow up of function and lead integrity after cranial MRI in 356 patients with conventional cardiac pacemakers

BACKGROUND

Conventional cardiac pacemakers are still often regarded as a contraindication to magnetic resonance imaging (MRI). We conducted this study to support the hypothesis that it is safe to scan patients with cardiac pacemakers in a 1.5 Tesla MRI, if close supervision and monitoring as well as adequate pre- and postscan programming is provided.

METHODS

We followed up 356 patients (age 61.3 ± 9.1 yrs., 229 men) with single (n = 132) or dual chamber (n = 224) cardiac pacemakers and urgent indication for a cranial MRI for 12 months. The scans were performed at 1.5T. During the scan patients were monitored with a 3-lead ECG and pulse oximetry. Prior to the scan pacemakers were programmed according to our own protocol.

RESULTS

All 356 scans were completed without complications. No arrhythmias were induced, programmed parameters remained unchanged. No pacemaker dysfunction was identified. Follow-up examinations were performed immediately, 2 weeks, 2, 6, and 12 months after the scan. There was no significant change of pacing capture threshold (ventricular 0.9 ± 0.4 V@0.4 ms, atrial 0.9 ± 0.3 V@0.4 ms) immediately (ventricular 1.0 ± 0.3 V@0.4 ms, atrial 0.9 ± 0.4 V@0.4 ms) or at 12 months follow-up examinations (ventricular 0.9 ± 0.2 V@0.4 ms, atrial 0.9 ± 0.3 V@0.4 ms). There was no significant change in sensing threshold (8.0 ± 4.0 mV vs. 8.1 ± 4.2 mV ventricular lead, 2.0 ± 0.9 mV vs. 2.1 ± 1.0 mV atrial lead) or lead impedance (ventricular 584 ± 179 Ω vs. 578 ± 188 Ω, atrial 534 ± 176 Ω vs. 532 ± 169 Ω) after 12 months.

CONCLUSIONS

This supports the evidence that patients with conventional pacemakers can safely undergo cranial MRI in a 1.5T system with suitable preparation, supervision and precautions. Long term follow-up did not reveal significant changes in pacing capture nor sensing threshold.

Effects of external electrical and magnetic fields on pacemakers and defibrillators: from engineering principles to clinical practice

The overall risk of clinically significant adverse events related to EMI in recipients of CIEDs is very low. Therefore, no special precautions are needed when household appliances are used. Environmental and industrial sources of EMI are relatively safe when the exposure time is limited and distance from the CIEDs is maximized. The risk of EMI-induced events is highest within the hospital environment. Physician awareness of the possible interactions and methods to minimize them is warranted.

Safety of MRIs in patients with pacemakers and defibrillators

With a burgeoning population, increases in life expectancy, and expanding indications, the number of patients with cardiac devices such as pacemakers and implantable cardioverter defibrillators continues to increase each year. A majority of these patients will develop an indication for magnetic resonance imaging (MRI) in their lifetime. MRIs have established themselves as one of the most powerful imaging tools for a variety of conditions. However, given the historic safety concerns, many physicians are reluctant to use MRIs in this patient population. In this paper, we discuss the potential adverse effects of MRIs in patients with cardiac devices, review key studies that have addressed strategies to limit adverse effects, and provide our cardiovascular MRI laboratory's protocol for imaging patients with implanted cardiac devices.

ACR guidance document on MR safe practices: 2013

Because there are many potential risks in the MR environment and reports of adverse incidents involving patients, equipment and personnel, the need for a guidance document on MR safe practices emerged. Initially published in 2002, the ACR MR Safe Practices Guidelines established de facto industry standards for safe and responsible practices in clinical and research MR environments. As the MR industry changes the document is reviewed, modified and updated. The most recent version will reflect these changes.

Approach to the patient with transient alteration of consciousness

Evaluating transient impairment of consciousness is critical to diagnose epileptic seizures, syncope, parasomnias, organic encephalopathies, and psychogenic nonepileptic seizures. Effective evaluation of episodic unconscious events demands interactive interviewing of the patient and witnesses of the events, with judgment as to historians' observational abilities. When generalized tonic-clonic seizures have been witnessed by medical staff or other reliable observers, a search for concomitant nonconvulsive events and for comorbid illnesses often elucidates diagnoses unsuspected by the referring physician. Consultation for stupor-coma should not miss a potentially reversible acute severe encephalopathy, particularly when reversibility requires timely therapy. Perspicacious analyses of complex cognitive-motor phenomena support judicious application of diagnostic procedures, including brief or prolonged EEG and video-EEG, EKG tilt-table testing, EKG loop monitoring, and brain imaging.

MRI-Conditional Cardiac Implantable Electronic Devices: What's New and What Can We Expect in the Future?

OPINION STATEMENT

The use of magnetic resonance imaging (MRI) as a diagnostic technique is rapidly expanding. The number of patients who undergo implantation of permanent pacemaker, implantable cardioverter defibrillator (ICD), and/or cardiac resynchronization therapy devices is increasing in parallel. Cardiovascular implants are subject to potentially harmful effects from MRI, and the routine use of this imaging modality for patients with standard cardiovascular devices is contraindicated. Several recent publications have suggested that MRI can safely be performed in standard cardiovascular device recipients with appropriate patient selection, device programming, and strict monitoring. In addition, MRI "conditional" device systems are now available that are specifically designed to be safe in the MRI environment. Such new technologies may simplify and improve overall safety of MRI in the setting of pacemaker and ICD systems. Although the availability of MRI conditional devices represents a significant breakthrough, their current use is limited to specific MRI conditions. MRI conditional cardiac device technology will likely continue to evolve with increased efforts to improve simplicity, safety, and generalizability under all MRI conditions.

MRI in patients with pacemakers: overview and procedural management

BACKGROUND

Magnetic resonance imaging (MRI) is generally contraindicated for patients with a pacemaker (PM) or implantable cardiac defibrillator (ICD), because of the risk of life-threatening interference with the device. Nevertheless, the question whether to perform MRI despite the presence of these devices can still arise when MRI is vitally indicated. In some hospitals, special precautionary measures are taken so that MRI can be performed in such cases.

METHODS

This review is based on the authors' experience in 42 patients who underwent MRI at our university hospital, on the pertinent literature, and on the recommendations of medical societies.

RESULTS

Because of its excellent image quality, MRI is often an indispensable diagnostic tool. Structured multidisciplinary management enables it to be performed safely even in patients with a PM or ICD. Pre- and post-MRI checks of the device are recommended, as well as extensive monitoring and the availability of the necessary personnel to deal with an emergency. In general, the pacing and defibrillator functions should be deactivated; for pacemaker-dependent patients, the asynchronous pacing mode should be activated. No serious incidents have occurred when these precautions have been observed, either among our own patients or in the literature. Newer PM systems have been approved for MRI scanning under certain conditions.

CONCLUSION

In patients with a PM or ICD, the benefit of MRI may far outweigh its risks if the indication has been established for the particular patient as an interdisciplinary decision and if the appropriate precautions are observed during scanning. Now that newer PM systems have been approved for MRI scanning, the problem seems close to being solved.