Safe performance of magnetic resonance of the heart in patients with magnetic resonance conditional pacemaker systems: the safety issue of the ESTIMATE study

An algorithm for pacing and cardioverting electronic devices undergoing magnetic resonance imaging: The PACED-MRI protocol

OBJECTIVE

Cardiac implantable electronic devices (CIEDs) have traditionally been a contraindication for magnetic resonance imaging (MRI). However, there is an increasing amount of literature to suggest that MRI can be safely performed in select patients with pacemakers and implantable cardioverter defibrillators by following a standardized protocol. We created an institutional protocol, made accessible as an online form, that is primarily technologist-driven and does not require direct electrophysiologist supervision. The purpose of this study was to evaluate the PACEDMRI protocol for screening and completing MRI in patients with MR conditional CIEDs.

SUBJECTS AND METHODS

After the implementation of our standardized PACED-MRI protocol, patients with MR conditional CIEDs who were referred for MRI were included in the study. On the day of the MRI, the device company representative utilized our protocol accessed through PACEDMRI.com. If all parameters and criteria within the protocol were met, the examination proceeded. The device representative programed the CIED to the appropriate mode for MRI as instructed by the PACED-MRI protocol. CIED interrogation was performed immediately before and after MRI. The on-call electrophysiology nurse practitioner was notified only if the protocol instructed the team to not proceed with MRI. CIED programming changes, malfunctions, and intraprocedural events were documented. Additionally, any adverse outcomes were recorded including peri-MRI symptom onset, arrhythmia, and death.

RESULTS

One hundred thirty-eight MRI examinations were performed on patients with MR conditional CIEDs (100 pacemakers: 38 implantable cardiac defibrillators). There was no incidence of symptom onset requiring early termination of the MRI, death, or arrhythmic events during or after MRI. No significant changes in lead parameters, including sensing amplitudes, lead thresholds, or lead impedances were noted on post-MRI device interrogation. Out of the 138 completed MRIs, the on-call electrophysiology provider was notified on one, non-urgent occasion.

CONCLUSION

The implementation of the standardized, technologists-driven PACED-MRI protocol allowed for a multidisciplinary approach to MRI for patients with MR conditional CIEDs. This study demonstrates that the PACED-MRI protocol can be used for patients with MR conditional CIEDs undergoing MRI without the need for direct electrophysiologist supervision.

Current Status and Issues Concerning Magnetic Resonance Imaging in Patients with a Magnetic Resonance Conditional Cardiac Implantable Electrical Device: A Single-center Study

Objective Following the introduction of magnetic resonance (MR)-conditional cardiac implantable electrical devices (CIEDs), patients with CIEDs have undergone MRI scanning more frequently. As the required settings of MRI equipment for scanning patients with a CIED vary by device, a number of precautions should be taken to allow safe examinations, including the confirmation of conditions and selection of MRI modes appropriate for pacing status in individual patients. In this study, we examined the current status and issues concerning the performance of MRI examinations in patients with an MRI-conditional CIED. Method and Results We reviewed a total of 262 MRI scans. The most common site of MRI scanning was the head, followed by the spine, abdomen, and heart in order. Regarding the MRI mode, DOO was most often used, followed by OFF, AOO, and finally VOO mode, to maintain atrioventricular synchrony. Although no obvious adverse events were observed related to MRI scanning, there were several cases encountered that might have been predisposed to a significant incident or in which the patient's intrinsic pulse rates or subjective symptoms changed before and during scanning. Conclusion As MRI is a very useful diagnostic tool for cerebrovascular diseases and orthopedic disorders, the demand for MRI scanning is high when treating these areas. Although MRI scanning in patients with MR-conditional devices was performed without any adverse events, there were incidents that could have potentially led to major harm. This highlights the importance of confirming the appropriate MRI mode is being used before scanning and monitoring patients during scanning.

Utility of Noncontrast Magnetic Resonance Angiography for Aneurysm Follow-Up and Detection of Endoleaks after Endovascular Aortic Repair

Objective

To assess the noncontrast two-dimensional single-shot balanced turbo-field-echo magnetic resonance angiography (b-TFE MRA) features of the abdominal aortic aneurysm (AAA) status following endovascular aneurysm repair (EVAR) and evaluate to detect endoleaks (ELs).

Materials and Methods

We examined four aortic stent-grafts in a phantom study to assess the degree of metallic artifacts. We enrolled 46 EVAR-treated patients with AAA and/or common iliac artery aneurysm who underwent both computed tomography angiography (CTA) and b-TFE MRA after EVAR. Vascular measurements on CTA and b-TFE MRA were compared, and signal intensity ratios (SIRs) of the aneurysmal sac were correlated with the size changes in the AAA after EVAR (AAA prognoses). Furthermore, we examined six feasible b-TFE MRA features for the assessment of ELs.

Results

There were robust intermodality (r = 0.92–0.99) correlations and interobserver (intraclass correlation coefficient = 0.97–0.99) agreement. No significant differences were noted between SIRs and aneurysm prognoses. Moreover, “mottled high-intensity” and “creeping high-intensity with the low-band rim” were recognized as significant imaging findings suspicious for the presence of ELs (p < 0.001), whereas “no signal black spot” and “layered high-intensity area” were determined as significant for the absence of ELs (p < 0.03). Based on the two positive features, sensitivity, specificity, and accuracy for the detection of ELs were 77.3%, 91.7%, and 84.8%, respectively. Furthermore, the k values (0.40–0.88) displayed moderate-to-almost perfect agreement.

Conclusion

Noncontrast MRA could be a promising imaging modality for ascertaining patient follow-up after EVAR.

Pearls and Pitfalls in Pediatric Fontan Operation Imaging

The Fontan operation or the total cavopulmonary connection is a palliative surgery for single ventricle congenital heart disease where the systemic venous return circumvents a pumping chamber and flows directly into the pulmonary circuit. With surgical and medical advances, there has been improvement in life expectancy of these patients, however, it has also resulted in unique complications from the physiology that requires diligent surveillance. A critical component relies on optimal imaging for diagnosis and treatment of these complications. This article describes the normal anatomy of the Fontan circulation, current imaging modalities and techniques, and frequently encountered complications seen when imaging the patients who have undergone Fontan palliation.

Clinical safety of ProMRI implantable cardioverter-defibrillator systems during head and lower lumbar magnetic resonance imaging at 1.5 Tesla

Magnetic resonance imaging (MRI) has long been contraindicated in patients with implanted pacemakers, defibrillators, and cardiac resynchronisation therapy (CRT) devices due to the risk of adverse effects through electromagnetic interference. Since many recipients of these devices will have a lifetime indication for an MRI scan, the implantable systems should be developed as ‘MRI-conditional’ (be safe for the MRI environment under predefined conditions). We evaluated the clinical safety of several Biotronik ProMRI (‘MRI-conditional’) defibrillator and CRT systems during head and lower lumbar MRI scans at 1.5 Tesla. The study enrolled 194 patients at 22 sites in Australia, Canada, and Europe. At ≥9 weeks after device implantation, predefined, non-diagnostic, specific absorption rate (SAR)-intensive head and lower lumbar MRI scans (total ≈30 minutes per patient) were performed in 146 patients that fulfilled pre-procedure criteria. Three primary endpoints were evaluated: freedom from serious adverse device effects (SADEs) related to MRI and defibrillator/CRT (leading to death, hospitalisation, life-threatening condition, or potentially requiring implanted system revision or replacement), pacing threshold increase, and sensing amplitude decrease, all at the 1-month post-MRI clinical visit. No MRI-related SADE occurred. Lead values remained stable, measured in clinic and monitored daily by the manufacturer home monitoring technology.

Evaluation of the safety of MRI scans in patients undergoing dual-chamber pacemaker implantation

The safety of magnetic resonance imaging (MRI) scans in patients undergoing dual-chamber pacemaker (Medtronic's EnRhythm MRI SureScan IPG (implantable pulse generator) and CapSureFix MRI pacing electrodes) implantation were evaluated. A total of 86 patients undergoing this pacemaker implantation who were admitted to Huanggang Hospital from June 2006 to March 2017 were continuously selected. On average 6.8±2.3 months after the implantation, the first MRI scan was conducted. The mean scan time was 2.2±0.9 and mean duration was 45.6±12.3 min; mean follow-up visit period was 40.5±15.6 months, and after follow-up, all the abnormal symptoms of patients and pacemaker abnormalities after scans were recorded. Causes of receiving MRI scans included neurological diseases (27%), spinal diseases (14%), cancers (26%), joint injuries (25%) and visceral systems (8%). A total of 12 cases (14.0%) showed significant discomfort symptoms, 10 cases (11.6%) showed pacemaker abnormalities, and the incidence rate was 25.6%. Multivariate logistic regression analysis showed that the basic types of cardiovascular diseases, dependence on pacemakers, duration of education, pacing threshold, impedance and MRI scan time were related to the occurrence of adverse scan results (p<0.05). In conclusion, MRI scans show that MRI-compatible dual-chamber pacemaker was relatively safe.

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.

Safety of Magnetic Resonance Imaging in Patients with Cardiac Devices

BACKGROUND

Patients who have pacemakers or defibrillators are often denied the opportunity to undergo magnetic resonance imaging (MRI) because of safety concerns, unless the devices meet certain criteria specified by the Food and Drug Administration (termed "MRI-conditional" devices).

METHODS

We performed a prospective, nonrandomized study to assess the safety of MRI at a magnetic field strength of 1.5 Tesla in 1509 patients who had a pacemaker (58%) or an implantable cardioverter-defibrillator (42%) that was not considered to be MRI-conditional (termed a "legacy" device). Overall, the patients underwent 2103 thoracic and nonthoracic MRI examinations that were deemed to be clinically necessary. The pacing mode was changed to asynchronous mode for pacing-dependent patients and to demand mode for other patients. Tachyarrhythmia functions were disabled. Outcome assessments included adverse events and changes in the variables that indicate lead and generator function and interaction with surrounding tissue (device parameters).

RESULTS

No long-term clinically significant adverse events were reported. In nine MRI examinations (0.4%; 95% confidence interval, 0.2 to 0.7), the patient's device reset to a backup mode. The reset was transient in eight of the nine examinations. In one case, a pacemaker with less than 1 month left of battery life reset to ventricular inhibited pacing and could not be reprogrammed; the device was subsequently replaced. The most common notable change in device parameters (>50% change from baseline) immediately after MRI was a decrease in P-wave amplitude, which occurred in 1% of the patients. At long-term follow-up (results of which were available for 63% of the patients), the most common notable changes from baseline were decreases in P-wave amplitude (in 4% of the patients), increases in atrial capture threshold (4%), increases in right ventricular capture threshold (4%), and increases in left ventricular capture threshold (3%). The observed changes in lead parameters were not clinically significant and did not require device revision or reprogramming.

CONCLUSIONS

We evaluated the safety of MRI, performed with the use of a prespecified safety protocol, in 1509 patients who had a legacy pacemaker or a legacy implantable cardioverter-defibrillator system. No long-term clinically significant adverse events were reported. (Funded by Johns Hopkins University and the National Institutes of Health; ClinicalTrials.gov number, NCT01130896 .).

Feasibility, safety, and potential demand of emergent brain magnetic resonance imaging of patients with cardiac implantable electronic devices

Background

The feasibility, safety, and potential demand of emergent magnetic resonance imaging (MRI) of patients with a cardiac implantable electronic device (CIED) in emergency situations are unknown.

Methods

We retrospectively compared emergent and scheduled MRI orders for patients with CIEDs at Kameda General Hospital, a tertiary hospital in Japan, from October 2012 to September 2016.

Results

We identified 11 emergent MRI orders via the emergency room and 38 scheduled MRI orders. Although the baseline characteristics were similar between the two groups, brain scanning was predominant in emergent scanning (p=0.002). The reasons for MRI and physicians who ordered it were also significantly different between the two groups (p<0.001, p=0.03, respectively). Among the emergent orders via the emergency room, 10 out of 11 were brain scans. Nine out of 10 patients underwent successful emergent brain MRI. The time from arrival at the emergency room to MRI was 144±29 min, and the time from the MRI order made by the cardiologist to its actual performance was 60±10 min. Four out of 9 patients had a diagnosis of acute stroke confirmed by emergent MRI, and two had emergent thrombolysis with a complete neurological recovery. All emergent scanning was conducted safely with no complications.

Conclusions

Our study found the potential demand of brain MRI of patients with CIEDs in emergency situations compared with scheduled scanning, which was shown to be feasible and safe for the diagnosis and treatment of an acute stroke.

Cardiac magnetic resonance imaging using wideband sequences in patients with nonconditional cardiac implanted electronic devices

BACKGROUND

Magnetic resonance imaging (MRI) has been performed safely in patients without MRI-conditional cardiac implantable electronic devices (CIEDs), but experience specifically with cardiac magnetic resonance imaging (CMR) is limited in this patient population.

OBJECTIVE

Evaluate the safety of CMR in non-MRI-conditional CIEDs and the interpretability of images using wideband sequences.

METHODS

We performed 114 consecutive CMR studies in 111 patients (mean age 59 ± 14 years, with 12 pacemakers, 73 implantable cardioverter defibrillators, 29 biventricular defibrillators) using a wideband pulse sequence for late gadolinium enhancement (LGE) imaging. A standardized protocol for device management and patient monitoring was followed. Patients were evaluated for major clinical adverse events and device parameter changes immediately after CMR and at clinical follow-up.

RESULTS

In total, 111 CMR studies were completed successfully. There were no patient deaths, new arrhythmias, immediate generator or lead failures, electrical resets, or pacing capture failures in dependent patients. Right atrial, right ventricular, and left ventricular lead impedances were significantly lower post CMR, with median differences -7 Ω (interquartile range [IQR] -20 to 0 Ω; P < .0001), 0 Ω (IQR -19 to 0 Ω; P = .0001), and -10 Ω (IQR -30 to 0 Ω; P = .023), respectively. These changes persisted through the follow-up period, with median differences -18.5 Ω (IQR -41 to -66 Ω; P = .007), -19 Ω (IQR -44 to -7 Ω; P = .006), and -30 Ω (IQR -130 to 0 Ω; P = .003), respectively. Ninety-seven studies (87%) had no artifact limiting interpretation.

CONCLUSIONS

CMR can be performed safely in non-MRI-conditional CIEDs using a standardized protocol. Use of a wideband pulse sequence for LGE imaging yields a high rate of studies unaffected by artifact.

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.

Deactivation vs. asynchronous pacing - prospective evaluation of a protocol for rhythm management in patients with magnetic resonance conditional pacemakers undergoing adenosine stress cardiovascular magnetic resonance imaging

Background

Cardiovascular Magnetic Resonance (CMR) imaging with adenosine stress is an important diagnostic tool in patients with known or suspected coronary artery disease (CAD). However, the method is not yet established for CAD patients with pacemakers (PM) in clinical practice. A possible reason is that no recommendations exist for PM setting (paused pacing or asynchronous mode) during adenosine stress. We elaborated a protocol for rhythm management in clinical routine for PM patients that considers heart rate changes under adenosine using a test infusion of adenosine in selected patients.

Methods

47 consecutive patients (mean age 72.3 ± 10,0 years) with MR conditional PM and known or suspected CAD who underwent CMR in clinical routine were studied in this prospective observational study. PM indications were sinus node dysfunction (SND, n = 19; 40,4%), atrioventricular (AV) block (n = 26; 55.3%) and bradyarrhythmia in permanent atrial fibrillation (AF, n = 2; 4.3%). In patients with SND, normal AV-conduction and resting HR >45 bpm at the time of CMR and in AF the PM was deactivated for the scan. In intermittent AV-block a test infusion of adenosine was given prior to the scan. All patients with permanent higher degree sinuatrial or AV-block or deterioration of AV-conduction in the adenosine test were paced asynchronously during CMR, in patients with preserved AV-conduction under adenosine the pacemaker was deactivated. CMR protocol included cine imaging, adenosine stress perfusion and late gadolinium enhancement.

Results

The adenosine test was able to differentiate between mandatory PM stimulation during CMR and safe deactivation of the device. In patients with permanent sinuatrial or AV-block (n = 11; 23.4%) or deterioration of AV conduction in the adenosine test (n = 5, 10.6%) asynchronous pacing above resting heart rate did not interfere with intrinsic rhythm, no competitive stimulation was seen during the scan. 10 of 15 (66,7%) patients with intermittent AV-block showed preserved AV-conduction under adenosine. As in SND and AF deactivation of the PM showed to be safe during CMR, no bradycardia was observed.

Conclusion

Our protocol for rhythm management during adenosine stress CMR showed to be feasible and safe and may be recommended for pacemaker patients undergoing routine CMR.

Comprehensive review on cardio-oncology: Role of multimodality imaging

Cancer and cardiovascular disease are the two leading causes of mortality worldwide. Evolving oncologic therapy, including the use of newer targeted agents, has led to an improvement in survival from childhood- and adult-onset cancers. Consequently, there has been a growing realization of cardiotoxic complications related to cancer therapy, with some complications manifesting over months to decades after completion of cancer treatment. This paper reviews cancer therapeutics-related cardiovascular toxicity and its manifestations, multimodality imaging techniques for surveillance and detection of this complication, and the current state of knowledge in this emerging field.

Review of Journal of Cardiovascular Magnetic Resonance 2015

There were 116 articles published in the Journal of Cardiovascular Magnetic Resonance (JCMR) in 2015, which is a 14 % increase on the 102 articles published in 2014. The quality of the submissions continues to increase. The 2015 JCMR Impact Factor (which is published in June 2016) rose to 5.75 from 4.72 for 2014 (as published in June 2015), which is the highest impact factor ever recorded for JCMR. The 2015 impact factor means that the JCMR papers that were published in 2013 and 2014 were cited on average 5.75 times in 2015. The impact factor undergoes natural variation according to citation rates of papers in the 2 years following publication, and is significantly influenced by highly cited papers such as official reports. However, the progress of the journal's impact over the last 5 years has been impressive. Our acceptance rate is <25 % and has been falling because the number of articles being submitted has been increasing. In accordance with Open-Access publishing, the JCMR articles go on-line as they are accepted with no collating of the articles into sections or special thematic issues. For this reason, the Editors have felt that it is useful once per calendar year to summarize the papers for the readership into broad areas of interest or theme, so that areas of interest can be reviewed in a single article in relation to each other and other recent JCMR articles. The papers are presented in broad themes and set in context with related literature and previously published JCMR papers to guide continuity of thought in the journal. We hope that you find the open-access system increases wider reading and citation of your papers, and that you will continue to send your quality papers to JCMR for publication.

Cardiac Implantable Electronic Device Safety during Magnetic Resonance Imaging

Background and Objectives

Although magnetic resonance imaging (MRI) conditional cardiac implantable electronic devices (CIEDs) have become recently available, non-MRI conditional devices and the presence of epicardial and abandoned leads remain a contraindication for MRIs.

Subjects and Methods

This was a single center retrospective study, evaluating the clinical outcomes and device parameter changes in patients with CIEDs who underwent an MRI from June 1992 to March 2015. Clinical and device related information was acquired by a thorough chart review.

Results

A total of 40 patients, 38 with a pacemaker (including epicardially located pacemaker leads) and 2 with implantable cardioverter defibrillators, underwent 50 MRI examinations. Among the patients, 11 had MRI conditional CIEDs, while the remaining had non-MRI conditional devices. Among these patients, 23 patients had traditional contraindications for an MRI: (1) nonfunctional leads (n=1, 2.5%), (2) epicardially located leads (n=9, 22.5%), (3) scanning area in proximity to a device (n=9, 22.5%), (4) devices implanted within 6 weeks (n=2, 5%), and (5) MRI field strength at 3.0 Tesla (n=6, 15%). All patients underwent a satisfactory MRI examination with no adverse events during or after the procedure. There were no significant changes in parameters or malfunctioning devices in any patients with CIEDs.

Conclusion

Under careful monitoring, MRI is safe to perform on patients with non-MRI conditional CIEDs, remnant leads, and epicardially located leads, as well as MRI-conditional devices.

CT and MR imaging of the thoracic aorta

At present time, both CT and MRI are valuable techniques in the study of the thoracic aorta. Nowadays, CT represents the most widely employed technique for the study of the thoracic aorta. The new generation CTs show sensitivities up to 100% and specificities of 98-99%. Sixteen and wider row detectors provide isotropic pixels, mandatory for the ineludible longitudinal reconstruction. The main limits are related to the X-ray dose expoure and the use of iodinated contrast media. MRI has great potential in the study of the thoracic aorta. Nevertheless, if compared to CT, acquisition times remain longer and movement artifact susceptibility higher. The main MRI disadvantages are claustrophobia, presence of ferromagnetic implants, pacemakers, longer acquisition times with respect to CT, inability to use contrast media in cases of renal insufficiency, lower spatial resolution and less availability than CT. CT is preferred in the acute aortic disease. Nevertheless, since it requires iodinated contrast media and X-ray exposure, it may be adequately replaced by MRI in the follow up of aortic diseases. The main limitation of MRI, however, is related to the scarce visibility of stents and calcifications.

MRI Mode Programming for Safe Magnetic Resonance Imaging in Patients With a Magnetic Resonance Conditional Cardiac Device

Although diagnostically indispensable, magnetic resonance imaging (MRI) has been, until recently, contraindicated in patients with an implantable cardiac device. MR conditional cardiac devices are now widely used, but the mode programming needed for safe MRI has yet to be established. We reviewed the details of 41 MRI examinations of patients with a MR conditional device. There were no associated adverse events. However, in 3 cases, paced beats competed with the patient's own beats during the MRI examination. We describe 2 of the 3 specific cases because they illustrate these potentially risky situations: a case in which the intrinsic heart rate increased and another in which atrial fibrillation occurred. Safe MRI in patients with an MR conditional device necessitates detailed MRI mode programming. The MRI pacing mode should be carefully and individually selected.

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.

Feasibility and safety of adenosine cardiovascular magnetic resonance in patients with MR conditional pacemaker systems at 1.5 Tesla

BACKGROUND

Cardiovascular Magnetic Resonance (CMR) with adenosine stress is a valuable diagnostic tool in coronary artery disease (CAD). However, despite the development of MR conditional pacemakers CMR is not yet established in clinical routine for pacemaker patients with known or suspected CAD. A possible reason is that adenosine stress perfusion for ischemia detection in CMR has not been studied in patients with cardiac conduction disease requiring pacemaker therapy. Other than under resting conditions it is unclear whether MR safe pacing modes (paused pacing or asynchronous mode) can be applied safely because the effect of adenosine on heart rate is not precisely known in this entity of patients. We investigate for the first time feasibility and safety of adenosine stress CMR in pacemaker patients in clinical routine and evaluate a pacing protocol that considers heart rate changes under adenosine.

METHODS

We retrospectively analyzed CMR scans of 24 consecutive patients with MR conditional pacemakers (mean age 72.1 ± 11.0 years) who underwent CMR in clinical routine for the evaluation of known or suspected CAD. MR protocol included cine imaging, adenosine stress perfusion and late gadolinium enhancement.

RESULTS

Pacemaker indications were sinus node dysfunction (n = 18) and second or third degree AV block (n = 6). Under a pacing protocol intended to avoid competitive pacing on the one hand and bradycardia due to AV block on the other no arrhythmia occurred. Pacemaker stimulation was paused to prevent competitive pacing in sinus node dysfunction with resting heart rate >45 bpm. Sympatho-excitatory effect of adenosine led to a significant acceleration of heart rate by 12.3 ± 8.3 bpm (p < 0.001), no bradycardia occurred. On the contrary in AV block heart rate remained constant; asynchronous pacing above resting heart rate did not interfere with intrinsic rhythm.

CONCLUSION

Adenosine stress CMR appears to be feasible and safe in patients with MR conditional pacemakers. Heart rate response to adenosine has to be considered for the choice of pacing modes during CMR.

Review of Journal of Cardiovascular Magnetic Resonance 2014

There were 102 articles published in the Journal of Cardiovascular Magnetic Resonance (JCMR) in 2014, which is a 6% decrease on the 109 articles published in 2013. The quality of the submissions continues to increase. The 2013 JCMR Impact Factor (which is published in June 2014) fell to 4.72 from 5.11 for 2012 (as published in June 2013). The 2013 impact factor means that the JCMR papers that were published in 2011 and 2012 were cited on average 4.72 times in 2013. The impact factor undergoes natural variation according to citation rates of papers in the 2 years following publication, and is significantly influenced by highly cited papers such as official reports. However, the progress of the journal's impact over the last 5 years has been impressive. Our acceptance rate is <25% and has been falling because the number of articles being submitted has been increasing. In accordance with Open-Access publishing, the JCMR articles go on-line as they are accepted with no collating of the articles into sections or special thematic issues. For this reason, the Editors have felt that it is useful once per calendar year to summarize the papers for the readership into broad areas of interest or theme, so that areas of interest can be reviewed in a single article in relation to each other and other recent JCMR articles. The papers are presented in broad themes and set in context with related literature and previously published JCMR papers to guide continuity of thought in the journal. We hope that you find the open-access system increases wider reading and citation of your papers, and that you will continue to send your quality papers to JCMR for publication.

Clinical value of cardiovascular magnetic resonance in patients with MR-conditional pacemakers

AIMS

Magnetic resonance (MR) conditional pacemakers are increasingly implanted into patients who may need cardiovascular MR (CMR) subsequent to device implantation. We assessed the added value of CMR for diagnosis and management in this population.

METHODS AND RESULTS

CMR and pacing data from consecutive patients with MR conditional pacemakers were retrospectively reviewed. Images were acquired at 1.5 T (Siemens Magnetom Avanto). The indication for CMR and any resulting change in management was recorded. The quality of CMR was rated by an observer blinded to clinical details, and data on pacemaker and lead parameters were collected pre- and post-CMR. Seventy-two CMR scans on 69 patients performed between 2011 and 2015 were assessed. All scans were completed successfully with no significant change in lead thresholds or pacing parameters. Steady-state free precession (SSFP) cine imaging resulted in a greater frequency of non-diagnostic imaging (22 vs. 1%, P < 0.01) compared with gradient echo sequences (GRE). Right-sided pacemakers were associated with less artefact than left-sided pacemakers. Late gadolinium enhancement imaging was performed in 59 scans with only 2% of segments rated of non-diagnostic quality. The CMR data resulted in a new diagnosis in 27 (38%) of examinations; clinical management was changed in a further 18 (25%).

CONCLUSIONS

CMR in patients with MR conditional pacemakers provided diagnostic or management-changing information in the majority (63%) of our cohort. The use of gradient echo cine sequences can reduce rates of non-diagnostic imaging. Right-sided device implantation may be considered in patients likely to require CMR examination.

Role of imaging in the evaluation of single ventricle with the Fontan palliation

The Fontan operation for single ventricle palliation consists of the creation of a complete cavopulmonary connection, usually by incorporating inferior vena caval flow into a pulmonary arterial circulation already receiving flow from the superior vena cava. In single ventricle palliated in this way, the anatomy is complex, and the pathophysiological complications are frequent; so, cardiac imaging is a key aspect of clinical surveillance. Common problems that echocardiography and MRI may disclose and characterise in the Fontan palliation of single ventricle include obstruction of systemic venous and pulmonary arterial flow, atrioventricular and semilunar valve dysfunction, unintended collateral flow patterns, ventricular dysfunction, aortic arch obstruction, interatrial obstruction, fenestration flow and patch leaks. Despite the broad scope of these modalities for detection of such problems, often no single imaging method is comprehensive in any given patient. Therefore, physicians must recognise the limitations of each modality, and circumvent these by application of suitable alternatives. New imaging tools are becoming available, which may ultimately prove to be of value in the Fontan circulation. Proper application of diverse new technologies such as four dimensional flow, computational fluid dynamics and three-dimensional printing will require critical evaluation in the single ventricle population.

Non-invasive focus localization, right ventricular epicardial potential mapping in patients with an MRI-conditional pacemaker system - a pilot study

Background

With the advent of magnetic resonance imaging (MRI) conditional pacemaker systems, the possibility of performing MRI in pacemaker patients has been introduced. Besides for the detailed evaluation of atrial and ventricular volumes and function, MRI can be used in combination with body surface potential mapping (BSPM) in a non-invasive inverse potential mapping (IPM) strategy. In non-invasive IPM, epicardial potentials are reconstructed from recorded body surface potentials (BSP). In order to investigate whether an IPM method with a limited number of electrodes could be used for the purpose of non-invasive focus localization, it was applied in patients with implanted pacing devices. Ventricular paced beats were used to simulate ventricular ectopic foci.

Methods

Ten patients with an MRI-conditional pacemaker system and a structurally normal heart were studied. Patient-specific 3D thorax volume models were reconstructed from the MRI images. BSP were recorded during ventricular pacing. Epicardial potentials were inversely calculated from the BSP. The site of epicardial breakthrough was compared to the position of the ventricular lead tip on MRI and the distance between these points was determined.

Results

For all patients, the site of earliest epicardial depolarization could be identified. When the tip of the pacing lead was implanted in vicinity to the epicardium, i.e. right ventricular (RV) apex or RV outflow tract, the distance between lead tip position and epicardial breakthrough was 6.0 ± 1.9 mm.

Conclusions

In conclusion, the combined MRI and IPM method is clinically applicable and can identify sites of earliest depolarization with a clinically useful accuracy.

Electronic supplementary material

The online version of this article (doi:10.1007/s10840-015-0054-9) contains supplementary material, which is available to authorized users.

Role of Cardiac MR Imaging in Cardiomyopathies

Cardiac MR imaging has made major inroads in the new millennium in the diagnosis and assessment of prognosis for patients with cardiomyopathies. Imaging of left and right ventricular structure and function and tissue characterization with late gadolinium enhancement (LGE) as well as T1 and T2 mapping enable accurate diagnosis of the underlying etiology. In the setting of coronary artery disease, either transmurality of LGE or contractile reserve in response to dobutamine can assess the likelihood of recovery of function after revascularization. The presence of scar reduces the likelihood of a response to medical therapy and to cardiac resynchronization therapy in heart failure. The presence and extent of LGE relate to overall cardiovascular outcome in cardiomyopathies. A major role for cardiac MR imaging in cardiomyopathies is to identify myocardial scar for diagnostic and prognostic purposes.

A priori model independent inverse potential mapping: the impact of electrode positioning

INTRODUCTION

In inverse potential mapping, local epicardial potentials are computed from recorded body surface potentials (BSP). When BSP are recorded with only a limited number of electrodes, in general biophysical a priori models are applied to facilitate the inverse computation. This study investigated the possibility of deriving epicardial potential information using only 62 torso electrodes in the absence of an a priori model.

METHODS

Computer simulations were used to determine the optimal in vivo positioning of 62 torso electrodes. Subsequently, three different electrode configurations, i.e., surrounding the thorax, concentrated precordial (30 mm inter-electrode distance) and super-concentrated precordial (20 mm inter-electrode distance) were used to record BSP from three healthy volunteers. Magnetic resonance imaging (MRI) was performed to register the electrode positions with respect to the anatomy of the patient. Epicardial potentials were inversely computed from the recorded BSP. In order to determine the reconstruction quality, the super-concentrated electrode configuration was applied in four patients with an implanted MRI-conditional pacemaker system. The distance between the position of the ventricular lead tip on MRI and the inversely reconstructed pacing site was determined.

RESULTS

The epicardial potential distribution reconstructed using the super-concentrated electrode configuration demonstrated the highest correlation (R = 0.98; p < 0.01) with the original epicardial source model. A mean localization error of 5.3 mm was found in the pacemaker patients.

CONCLUSION

This study demonstrated the feasibility of deriving detailed anterior epicardial potential information using only 62 torso electrodes without the use of an a priori model.

Predictive value of single photon emission computerized tomography and computerized tomography in osteonecrosis after femoral neck fracture: a prospective study

PURPOSE

Osteonecrosis of the femoral head (ONFH) is a very common complication after femoral neck fracture. The purpose of this study was to assess the femoral head vascularity after femoral neck fracture using single photon emission computerized tomography and computerized tomography (SPECT/CT), and to evaluate its value in predicting ONFH.

METHODS

Between January 2008 and March 2011, 120 patients diagnosed with femoral neck fracture underwent SPECT-CT before the internal fixation. The fracture was classified according to the Garden classification. The ratios of the radionuclide uptake of the fractured femoral head to that of the contralateral femoral head (F/N) were calculated to assess the femoral head vascularity. After a minimum of two years' follow-up, magnetic resonance imaging (MRI) was used as the "gold standard" for the diagnosis of possible ONFH.

RESULTS

A total of 114 patients completed the study. The SPECT/CT examination showed that the F/N ratios of Garden I, II, III and IV were 2.6, 1.8, 0.8, and 0.6, respectively. At the time of the most recent follow-up, osteonecrosis developed in two of the 27 patients who had a Garden Stage-II fracture, in eight of the 34 patients who had a Garden Stage-III fracture, and nine of the 27 patients who had a Garden Stage-VI fracture. With a cutoff of 0.55 from the receiver operating characteristic (ROC) curve, F/N ratio showed a sensitivity of 97%, a specificity of 79%, a positive predictive value of 95%, and a negative predictive value of 19%.

CONCLUSION

SPECT-CT proved to be reliable and valid for predicting ONFH after femoral neck fracture.

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.