Safety of magnetic resonance imaging in patients with permanent pacemakers: a collaborative clinical approach.
ABSTRACT This study aimed to characterize the interactions of pacemakers with magnetic resonance imaging (MRI) and to identify device characteristics that could predict adverse interactions.
The safety of MRI in patients with indwelling pacemaker systems remains uncertain. Previous studies demonstrated safety in most patients, but unpredictable, potentially concerning changes in pacemaker behavior have occurred.
We prospectively studied patients with pacemaker devices in situ who were not pacemaker dependent and in whom MRI was essential for adequate diagnosis and treatment. All patients were monitored by electrocardiography and pulse oximetry during scanning; devices were interrogated and cardiac enzymes were measured before and after scanning.
Of 32 patients studied (46 MRI examinations), 28 patients had a dual-chamber system and one had a biventricular device. Regions scanned were the head and spine. Devices were reprogrammed to asynchronous pacing or sense-only mode in all except six patients before MRI. During six scanning episodes (five patients), "power-on" resetting of the device was noted. Magnet-mode pacing was noted during four episodes (three patients). Occasional premature ventricular contractions were noted in one patient. No significant changes in battery voltage, sensed P wave and R wave, pacing thresholds, lead impedance, or cardiac enzymes were noted immediately after MRI or at 1-month follow-up.
Overall, no significant changes were seen in pacemaker device function, and no adverse clinical events were observed. A minority of patients with older devices had unpredictable changes in device behavior, which stresses the need for close monitoring during and careful device interrogation after scanning.
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ABSTRACT: To assess the current knowledge about the potential hazard from MRI in patients with devices such as pacemakers and implantable cardioverter defibrillators (ICDs). 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. 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.Current Opinion in Cardiology 01/2015; 30(1):65-73. DOI:10.1097/HCO.0000000000000132 · 2.59 Impact Factor
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ABSTRACT: BackgroundConventional 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.MethodsWe 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.ResultsAll 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.ConclusionsThis 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.Journal of Cardiovascular Magnetic Resonance 06/2014; 16(1):39. DOI:10.1186/1532-429X-16-39 · 5.11 Impact Factor
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ABSTRACT: Magnetic resonance imaging (MRI) has been safely performed in some patients with cardiac implantable electronic devices (CIEDs) under careful protocols. Pacemaker dependent patients are often excluded, in part due to concern of "power-on reset" (PoR), which can result in a change from asynchronous to inhibited pacing with consequent inhibition of pacing due to noise from the MRI. We reviewed risk factors for PoR during MRI. Prospective data were collected starting in 2008 in patients with CIEDs undergoing clinically indicated MRI. Eligible patients were not pacemaker dependent. Devices were interrogated pre- and post-MRI, programmed to asynchronous pacing or inhibition mode with tachyarrhythmia therapies off, and reprogrammed to their original settings post-MRI. MRI scans (n=256) were performed in 198 patients with non-MRI conditional CIEDs between 2008-2013 (median age 66, IQ 57-77; 59% men). PoR occurred during 9 MRI scans (3.5%) in 8 patients. PoR was more frequent with Medtronic devices than other generator brands (n=9/139 vs. 0/117, 6% vs. 0%, p=0.005). Devices with PoR were all released before 2002 and were implanted from 1999 to 2004. Effects of PoR included a decrease in heart rate during MRI (n=4) and transient anomalous battery life indication (n=1). All devices functioned normally following MRI. PoR occurs infrequently but can cause deleterious changes to pacing mode and heart rate. MRI scans should not be performed in pacemaker dependent patients with older, at risk generators. Continuous monitoring during MRI is essential as unrecognized PoR may inhibit pacing or accelerate power depletion due to high pacing output. Copyright © 2014. Published by Elsevier Inc.Heart rhythm: the official journal of the Heart Rhythm Society 11/2014; 12(3). DOI:10.1016/j.hrthm.2014.10.039 · 4.92 Impact Factor