Magnetic Resonance Imaging-Conditional External Cardiac Defibrillator

HomeCirculation: Cardiovascular ImagingVol. 9, No. 10Magnetic Resonance Imaging-Conditional External Cardiac Defibrillator Free AccessEditorialPDF/EPUBAboutView PDFView EPUBSections ToolsAdd to favoritesDownload citationsTrack citationsPermissions ShareShare onFacebookTwitterLinked InMendeleyReddit Jump toFree AccessEditorialPDF/EPUBMagnetic Resonance Imaging-Conditional External Cardiac DefibrillatorExpanding Access and Safety During Magnetic Resonance Imaging Stephanie C. El Hajj, MD and Michael R. Gold, MD, PhD Stephanie C. El HajjStephanie C. El Hajj From the Division of Cardiology, Department of Medicine, Medical University of South Carolina, Charleston. and Michael R. GoldMichael R. Gold From the Division of Cardiology, Department of Medicine, Medical University of South Carolina, Charleston. Originally published11 Oct 2016https://doi.org/10.1161/CIRCIMAGING.116.005573Circulation: Cardiovascular Imaging. 2016;9:e005573Magnetic resonance imaging (MRI) is the most rapidly growing imaging modality in clinical medicine, including cardiac disorders.1 One of the limitations of MRI is the need to avoid certain metallic objects in close proximity to the MRI machine, including external cardiac defibrillators. Similarly, patients with implantable devices with ferromagnetic components are contraindicated for MRI because of the risks of heating, dislodgement, and other problems. Included in this contraindicated list are patients with implantable cardiac rhythm devices, although it is estimated that a large number of such patients will be indicated for an MRI.2 This has led to medical device manufacturers modifying the designs of pacemaker systems to make them MRI-conditional. The modifications included using less ferromagnetic material, developing lead wires with reduced radiofrequency heating to prevent thermal damage at the point of contact with the myocardium, and reducing electromagnetic interference to prevent inappropriate pacing and changes to provide battery protection. There are now robust data supporting the safety and reliability of MRI with the implantable pacemakers.3,4 MRI-conditional implantable cardioverter defibrillator systems have recently become available as well with several studies, supporting safety and low risk when exposed to 1.5-T whole-body MRI. Implantable cardioverter defibrillator systems evaluated after MRI revealed no delay in detection or treatment of ventricular tachyarrhythmias.5–7 However, these devices are inactivated for arrhythmia therapy while in the MRI bore.See Article by Schmidt et alPatients who have implantable cardioverter defibrillator systems have, by definition, an increased risk of ventricular arrhythmias. These patients, as well as other groups of cardiac patients and severely ill noncardiac patients, are at risk for cardiac arrhythmias and are not protected in the MRI procedure room. Arrhythmia diagnosis is equally challenging because electrocardiogram monitoring cannot be performed during MRI, so pulse oximetry is often used to assess heart rate. Cardiac arrest during MRI requires inactivating the scan, removing the patient from the bore, recording a rhythm, and defibrillating if appropriate. This significantly prolongs time to detection and time to return of spontaneous circulation, which is directly related to neurological outcomes and survival.8 Prompt defibrillation is now the cornerstone of resuscitation from cardiac arrest. Although the incidence of cardiac arrests in the MRI scanner is not known to our knowledge, it is logical to make MRI available and safer for high-risk patients.In this issue of Circulation: Cardiovascular Imaging, the study by Schmidt et al9 aimed to make a commercial external cardiac defibrillator 1.5-T MRI-conditional. They applied some of the same modifications used in MRI-conditional implantable cardioverter defibrillator systems. This included adding a low pass filter to remove the large amount of radiofrequency interference emitted by the generator. To prevent the MRI-induced heating of the cables, they constructed a long high-voltage cable using copper-insulated cable and placed radiofrequency traps constructed from copper tubes at increments along the cable. MRI-compatible 12-lead ECG systems are being developed; however, they were not available at the time of this study, so MRI-compatible hemodynamic and oxygenation monitors were used as a surrogate.Similar to the studies of the MRI-conditional implantable cardiac devices, the goals of this study included determining the safety of the equipment, the efficacy of the therapy (ie, defibrillation), and the preservation of image quality. Studies were performed in both swine and healthy human volunteers. Further studies are needed to validate these results and combine this system with the MRI-compatible electrocardiogram leads. It will also be important to establish whether transcutaneous pacing can be achieved with this system.This interesting article established the potential of MRI-conditional external cardiac defibrillators. If this system proves to be safe, effective, and can be commercialized, then this will help to eliminate one of the important barriers to MRI in high-risk or critically ill patients. With the growing field of MRI-guided interventions, an MRI-conditional external cardiac defibrillator with monitoring and pacing capabilities will be an important step toward providing care comparable to that in cardiac procedural rooms.DisclosuresNone.FootnotesThe opinions expressed in this article are not necessarily those of the editors or of the American Heart Association.Correspondence to Michael R. Gold, MD, PhD, Division of Cardiology, Department of Medicine, Medical University of South Carolina, 114 Doughty St, MSC 592, Charleston, SC 29425. E-mail [email protected]References1. 2015 MR Benchmark Report. IMV Medical Information Division, Inc.Google Scholar2. Kalin R, Stanton MS. Current clinical issues for MRI scanning of pacemaker and defibrillator patients.Pacing Clin Electrophysiol. 2005; 28:326–328. doi: 10.1111/j.1540-8159.2005.50024.x.CrossrefMedlineGoogle Scholar3. Gimbel JR, Bello D, Schmitt M, Merkely B, Schwitter J, Hayes DL, Sommer T, Schloss EJ, Chang Y, Willey S, Kanal E; Advisa MRI System Study Investigators. Randomized trial of pacemaker and lead system for safe scanning at 1.5 Tesla.Heart Rhythm. 2013; 10:685–691. doi: 10.1016/j.hrthm.2013.01.022.CrossrefMedlineGoogle Scholar4. Wilkoff BL, Bello D, Taborsky M, Vymazal J, Kanal E, Heuer H, Hecking K, Johnson WB, Young W, Ramza B, Akhtar N, Kuepper B, Hunold P, Luechinger R, Puererfellner H, Duru F, Gotte MJ, Sutton R, Sommer T; EnRhythm MRI SureScan Pacing System Study Investigators. Magnetic resonance imaging in patients with a pacemaker system designed for the magnetic resonance environment.Heart Rhythm. 2011; 8:65–73. doi: 10.1016/j.hrthm.2010.10.002.CrossrefMedlineGoogle Scholar5. Gold MR, Sommer T, Schwitter J, Kanal E, Bernabei MA, Love CJ, Surber R, Ramza B, Cerkvenik J, Merkely B. Impact of magnetic resonance imaging on ventricular tachyarrhythmia sensing: results of the Evera MRI Study.Heart Rhythm. 2016; 13:1631–1635. doi: 10.1016/j.hrthm.2016.05.014.CrossrefMedlineGoogle Scholar6. Schwitter J, Gold MR, Al Fagih A, Lee S, Peterson M, Ciuffo A, Zhang Y, Kristiansen N, Kanal E, Sommer T; Evera-MRI Study Investigators. Image quality of cardiac magnetic resonance imaging in patients with an implantable cardioverter defibrillator system designed for the magnetic resonance imaging environment.Circ Cardiovasc Imaging. 2016; 9:e004025. doi: 10.1161/CIRCIMAGING.115.004025.LinkGoogle Scholar7. Gold MR, Kanal E, Schwitter J, Sommer T, Yoon H, Ellingson M, Landborg L, Bratten T. Preclinical evaluation of implantable cardioverter-defibrillator developed for magnetic resonance imaging use.Heart Rhythm. 2015; 12:631–638. doi: 10.1016/j.hrthm.2014.12.012.CrossrefMedlineGoogle Scholar8. Rea TD, Eisenberg MS, Becker LJ, Murray JA, Hearne T. Temporal trends in sudden cardiac arrest: a 25-year emergency medical services perspective.Circulation. 2003; 107:2780–2785. doi: 10.1161/01.CIR.0000070950.17208.2A.LinkGoogle Scholar9. Schmidt EJ, Watkins RD, Zviman MM, Guttman MA, Wang W, Halperin HA. A magnetic resonance imaging–conditional external cardiac defibrillator for resuscitation within the magnetic resonance imaging scanner bore.Circ Cardiovasc Imaging. 2016; 9:e005091. doi: 10.1161/CIRCIMAGING.116.005091.LinkGoogle Scholar Previous Back to top Next FiguresReferencesRelatedDetails October 2016Vol 9, Issue 10 Advertisement Article InformationMetrics © 2016 American Heart Association, Inc.https://doi.org/10.1161/CIRCIMAGING.116.005573PMID: 27729367 Originally publishedOctober 11, 2016 Keywordsheart ratedefibrillatorsmagnetic resonance imagingEditorialsheatingcopperPDF download Advertisement SubjectsCardiopulmonary Resuscitation and Emergency Cardiac Care