CLINICAL RESEARCH: CARDIAC IMAGING
Magnetic Resonance Imaging at 1.5-T in Patients With Implantable Cardioverter-Defibrillators
Claas P. Naehle, MD*,*,
Katharina Strach, MD*,
Daniel Thomas, MD*,
Carsten Meyer, MD*,
Markus Linhart, MD ,
Sascha Bitaraf, MD ,
Harold Litt, MD, PhD ,
Jörg Otto Schwab, MD,
Hans Schild, MD* and
Torsten Sommer, MD||
* Department of Radiology, University of Bonn, Bonn, Germany
Department of Cardiology, University of Bonn, Bonn, Germany
Department of Internal Medicine–Cardiology, Katholisches Klinikum Koblenz–Marienhof, Koblenz, Germany
Department of Radiology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania
|| Department of Radiology, German Red Cross Hospital, Neuwied, Germany
Manuscript received January 22, 2009;
revised manuscript received March 9, 2009,
accepted April 15, 2009.
* Reprint requests and correspondence: Dr. Claas P. Naehle, Department of Radiology, University of Bonn, Sigmund-Freud-Str. 25, 53105 Bonn, Germany (Email: cp{at}naehle.net).
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Abstract
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Objectives: Our aim was to establish and evaluate a strategy for safe performance of magnetic resonance imaging (MRI) at 1.5-T in patients with implantable cardioverter-defibrillators (ICDs).
Background: Expanding indications for ICD placement and MRI becoming the imaging modality of choice for many indications has created a growing demand for MRI in ICD patients, which is still considered an absolute contraindication.
Methods: Non–pacemaker-dependent ICD patients with a clinical need for MRI were included in the study. To minimize radiofrequency-related lead heating, the specific absorption rate was limited to 2 W/kg. ICDs were reprogrammed pre-MRI to avoid competitive pacing and potential pro-arrhythmia: 1) the lower rate limit was programmed as low as reasonably achievable; and 2) arrhythmia detection was programmed on, but therapy delivery was programmed off. Patients were monitored using electrocardiography and pulse oximetry. All ICDs were interrogated before and after the MRI examination and after 3 months, including measurement of pacing capture threshold, lead impedance, battery voltage, and serum troponin I.
Results: Eighteen ICD patients underwent a total of 18 MRI examinations at 1.5-T; all examinations were completed safely. All ICDs could be interrogated and reprogrammed normally post-MRI. No significant changes of pacing capture threshold, lead impedance, and serum troponin I were observed. Battery voltage decreased significantly from pre- to post-MRI. In 2 MRI examinations, oversensing of radiofrequency noise as ventricular fibrillation occurred. However, no attempt at therapy delivery was made.
Conclusions: MRI of non–pacemaker-dependent ICD patients can be performed with an acceptable risk/benefit ratio under controlled conditions by taking both MRI- and pacemaker-related precautions. (Implantable Cardioverter Defibrillators and Magnetic Resonance Imaging of the Heart at 1.5-Tesla; NCT00356239)
Key Words: magnetic resonance imaging • implantable cardioverter-defibrillator • safety
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Abbreviations and Acronyms
| | ATP = antitachycardia pacing | | DC = direct current | | ICD = implantable cardioverter-defibrillator | | MRI = magnetic resonance imaging | | PM = pacemaker | | RF = radiofrequency | | SAR = specific absorption rate |
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Recent studies have suggested that magnetic resonance imaging (MRI) at 1.5-T can be performed safely in patients with implanted cardiac pacemakers (PMs) in carefully selected circumstances. In comparison with PMs, safety issues in imaging of patients with implantable cardioverter-defibrillators (ICDs) are more complex. Although MRI was performed without complications previously (1–5), the presence of an ICD is still considered an off-label procedure and a strong relative contraindication for MRI (6,7), and most patients with ICDs are denied for MRI despite its unparalleled capabilities for diagnosis and planning of treatment. The purpose of our study was to establish a strategy for safe performance of MRI at 1.5-T in ICD patients and to evaluate the safety and feasibility of this strategy.
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Methods
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Study subjects.
Eighteen patients with an ICD and an urgent clinical indication for MRI were enrolled prospectively. Inclusion and exclusion criteria are shown in Table 1. The study design is summarized in Table 2. The institutional review board of the relevant institution approved the study protocol. Signed informed consent was obtained from all subjects.
MRI system and sequences.
All MRI examinations were performed on an actively shielded 1.5-T MRI scanner (Intera, 1.5-T, Philips, Best, the Netherlands) (gradient system: maximum amplitude 33 mT/m, maximum slew rate 80 mT/m/s, minimum rise time 0.41 ms). All clinically relevant MRI sequences necessary for diagnosis were performed. To minimize the risk of radiofrequency (RF)-related lead heating, the specific absorption rate (SAR) was limited to 2 W/kg.
Pre/post-MRI ICD evaluation and reprogramming.
All ICDs were interrogated before and immediately after MRI (Fig. 1). The following parameter changes pre/post MRI were defined to be clinically significant and MRI-related: 1) pacing capture threshold increase  1.0 V at 0.4 ms pulse duration; 2) increase or decrease of pacing lead impedance to >2,000  or <200 ; 3) increase or decrease of high-voltage lead impedance to >80 or <10 (8); and 4) ability to interrogate the device. If any MRI-related parameter changes were noted, a chest X-ray and an ICD test were performed. Before MRI, all ICDs were reprogrammed to minimize the risk of interference with the MRI system (Fig. 1). Serum troponin I was measured within 1 h before and 12 to 24 h after MRI to detect myocardial injury. Each patient was asked to immediately inform the investigator of any torquing, movement, or heating sensation about the ICD pocket, and other unusual sensations during MRI.
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Figure 1 ICD Interrogation and Reprogramming Pre-MRI, Post-MRI, and at Follow-Up
ICD = implantable cardioverter-defibrillator; MRI = magnetic resonance imaging; 0X0 = sense-only mode.
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Statistical analysis.
Troponin I levels were compared using the Student t test; all other parameters were compared using the Wilcoxon signed rank test. The level of significance was set to a value of 0.05.
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Results
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The study group consisted of 18 consecutive patients (mean age 61.8 years) on which a total of 18 MRI examinations were performed. ICD models, ICD leads, and scanned MRI regions are given in Table 3. The 3-month follow-up interrogation was performed after 18 of 18 (100%) examinations (mean follow-up interval 92.8 days, range 73 to 115 days).
Clinical events during the MRI examinations.
All MRI examinations (100%) were completed safely. None of the patients reported any torque or heating sensations, or other unusual symptoms during MRI. No unexpected changes in heart rate or rhythm, indicating inhibition of ICD output, shock delivery, or sustained atrial or ventricular arrhythmias were observed during any MRI examination (0 of 18, 0%).
ICD reprogramming.
In 18 of 18 (100%) patients, the underlying intrinsic heart rate was >50 beats/min, and the ICDs were reprogrammed to an inhibited pacing mode with subthreshold pacing, or pacing was programmed "off" (Table 3). In 17 of 18 patients (94.4%), the ICD was programmed to a monitor-only mode (arrhythmia detection on, therapies delivery off). In 1 patient (1 of 18, 5.6%), both arrhythmia detection and therapy delivery were programmed "off," as a monitor-only mode was not available in the specific device (Atlas, St. Jude Medical, St. Paul, Minnesota). In no patient (18 of 18, 100%) did an electrical reset occur during MRI.
ICD status.
In all devices (18 of 18, 100%), the capability to interrogate the ICD device using telemetry remained preserved. No clinically significant change of pacing capture threshold or lead impedance was observed (Table 4). Mean percentage change in lead impedance from pre-MRI to post-MRI was –1.86 ± 5.10 , and from pre-MRI to follow-up 0.57 ± 4.43 . Mean battery voltage was 3.86 ± 1.48 V pre-MRI, 3.83 ± 1.48 V post-MRI, and 3.90 ± 1.52 V at follow-up (Table 4). The decrease in battery voltage from pre- to post-MRI was statistically significant (p = 0.0420). A full recovery of battery voltage at follow-up was observed after 4 of 16 (25.0%) MRI examinations. Mean charge time pre-MRI, post-MRI, and at follow-up are given in Table 4. There was a significant decrease in the charge time from 11.15 ± 4.86 s pre-MRI to 9.48 ± 4.28 s post-MRI (p = 0.0034).
RF oversensing/therapy delivery.
For 1 device (St. Jude Medical, Atlas) assessment of RF oversensing was not possible, as both tachyarrhythmia detection and therapy had to be deactivated in this device. For the remaining 17 magnetic resonance (MR) examinations, RF oversensing as ventricular arrhythmia occurred in 2 of 17 examinations (11.8%). As both devices (Guidant CPI Ventak Prizm DR and Guidant CPI Ventak Prizm 2 VR, Guidant [now Boston Scientific], Indianapolis, Indiana) had been reprogrammed to a detection-only mode before MRI according to the study protocol, no attempt at therapy delivery (0 of 2, 0%) was made.
Troponin I.
Eighteen blood samples were analyzed, and no increase of troponin I level above the upper normal limit of 0.1 ng/ml was observed after any of the examinations (0 of 18, 0%) (Table 4).
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Discussion
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ICDs primarily monitor heart rate and rhythm for malignant tachycardia and deliver antitachycardia pacing (ATP) or direct current (DC) shock delivery to restore normal heart rate and rhythm. Therefore, ICDs differ from PMs to a great extent: 1) increased ferromagnetic mass (larger battery, presence of transformer and capacitor), increasing magnetic translation forces and torque; 2) longer leads with a larger diameter with shock coils; 3) advanced integrated circuitry allowing for analysis of both heart rate and rhythm; and 4) additional hardware (e.g., transformer, integrated circuitry, capacitor) and software to allow for therapy delivery with risk of damage to hardware components and inappropriate therapy delivery due to oversensing of electromagnetic noise by the MRI system.
RF-related heating.
RF-related heating for ICD leads has been shown to reach up to 7.2°C in vitro (9), which is generally considered negligible in terms of safety and biologic effects (10). However, RF-induced heating is difficult to simulate in vitro given the numerous possible combinations of devices and leads and the infinite number of possible different geometric configurations of the leads within the chest, which are known to alter the amount of heating considerably (11). Therefore, to be conservative, we limited the SAR to 2.0 W/kg in our study to minimize the risk of RF-related lead heating. Maximum RF-induced heating occurs at the electrode-tissue boundary and may lead to deterioration of pacing thresholds (9,12). The finding that lead impedances and pacing thresholds remained unchanged in our study and that no increase in troponin I was measured after MRI confirm that no clinically relevant thermal injury occurred at the ICD lead tips (Fig. 2). These findings are concordant with previous studies and several case reports, which also did not find any evidence for thermal injury after MRI in ICD patients (1–5,9).
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Figure 2 Midventricular Short-Axis MRIs of the Heart in a Patient With a Chronic MI
(Left) Steady-state free precession sequence, demonstrating wall thinning of the septal wall. (Right) Three-dimensional inversion recovery viability imaging, indicating the myocardial scar in the septum (black arrow). Note the susceptibility artifacts in the right ventricle due to the implantable cardioverter-defibrillator lead (open arrows) and in the pectoral region due to the implantable cardioverter-defibrillator (*). MI = myocardial infarction; MRI = magnetic resonance imaging.
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MRI interference with ICD functionality.
Oversensing of RF Fields
In our study, oversensing of RF noise as ventricular fibrillation was observed in 2 of 17 MRI examinations (Fig. 3). Due to deactivation of therapy delivery before MRI, no attempt at therapy delivery was recorded (Fig. 4). To date, it seems highly unlikely that ICDs can perform DC shock delivery within the MR environment. For DC shock delivery (20 to 700 V), the battery voltage (3 to 6 V) has to be transformed to charge the capacitor. However, the static magnetic field saturates the transformer, resulting in a short circuit with ineffective voltage transformation and the inability to charge the capacitor (13). However, other important safety issues are associated with oversensing of MR noise by ICDs: 1) unintended attempts to charge the capacitor can cause battery depletion; 2) some ICD devices permanently inactivate therapy delivery after a certain number of unsuccessful attempts to charge the capacitor, which might necessitate device replacement; 3) inappropriate ATP due to RF oversensing could induce ventricular arrhythmia due to asynchronous stimulation; and 4) a short circuit within the electronic circuits may permanently damage the ICD (14,15), necessitating device replacement. Therefore, to minimize the risk of attempted inadequate therapy delivery due to RF oversensing, therapy delivery (ATP and DC shock) was completely deactivated before MRI.
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Figure 3 EGM Recorded at the Beginning of an MRI Sequence
Traces shown from top to bottom are: ventricular electrogram (EGM), shock coil EGM, and marker channel. Initial ventricular EGM shows regular sensing of intrinsic ventricular signals with correct classification as ventricular sensing (VS) (*). After the start of t scan sequence with radiofrequency pulses for image acquisition, oversensing of radiofrequency noise in the ventricular EGM occurs with classification as ventricular fibrillation (VF) (arrows) by the arrhythmia detection algorithm (see marker channel). MRI = magnetic resonance imaging.
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Figure 4 EGM With Sustained Oversensing of RF Noise by an ICD During MRI
Traces shown from top to bottom are ventricular electrogram (EGM), shock coil EGM, and marker channel. Radiofrequency (RF) noise (ventricular channel, top trace) is classified as ventricular fibrillation (VF) (arrows) by the arrhythmia detection algorithm (see marker channel). However, no therapy delivery was attempted as the device was reprogrammed to a monitor only mode (*) before MRI. Abbreviations as in Figure 1.
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Reed Switch
In magnetic fields >200 mT, the reed switch remains open in 50% of spatial orientations and is closed only in 50% of spatial orientations (13) with consecutive deactivation of therapy delivery. Reactivation of therapy delivery after opening of the reed switch is manufacturer dependent (16). Therefore, ICD reprogramming before MRI with deactivation of therapy delivery and ICD interrogation after MRI is mandatory to ensure appropriate device programming with reactivated arrhythmia detection and therapy delivery.
Capacitor Testing
The time needed to fully charge the capacitor is an important indicator for effective therapy delivery, because a prolonged charge time can lead to ineffective therapy delivery (17,18). In our study, the charge time decreased significantly from pre- to post-MRI measurement. We theorize that this decrease in charge time is not MRI related, but rather due to the charge test performed before MRI, leaving the capacitor already reformatted for post-MRI testing and leading to a decreased charge time by itself.
Battery Voltage
In the present study on ICDs in the MRI environment, a slight, but significant (p = 0.0420) decrease in battery voltage (3.86 ± 1.48 V vs. 3.83 ± 1.51 V) was demonstrated from pre- to post-MRI. Several mechanisms can lead to battery depletion: 1) charging of the capacitor due to oversensing of RF noise; 2) sustained activation of telemetry due to closure of the reed switch; and 3) electrical short circuits within the ICD. In the present studies, no attempts to charge the capacitor were noted, and it is unknown to what extent the activation of telemetry and possible short circuits contributed to the drop in battery voltage. Therefore, it is mandatory to perform a complete device interrogation immediately after MRI to assess if: 1) battery depletion; 2) an electrical reset with subsequent restoration of factory default settings; or 3) permanent inactivation of therapy delivery due to multiple attempts to charge the capacitor has occurred.
Contrary to previous PM studies, in which a complete recovery was noted in 66.1% of the MRI examinations (12), in this study a complete recovery of battery voltage was noted in only 4 of 16 examinations (25.0%). In addition, after 3 of 16 (18.8%) examinations in our study, a persisting decrease in battery voltage 0.05 V was observed. This finding may be of major importance for several reasons: 1) a decrease in battery voltage can lead to a prolonged charge time, which, in turn, delays therapy delivery for malignant ventricular tachycardia and decreases the likelihood of successful rhythm conversion (19); and 2) a decrease in battery voltage may necessitate early device replacement.
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Conclusions
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The results of the present study demonstrate that MR examinations in patients with ICDs may be performed safely under controlled conditions and using several precautionary measures, including: 1) minimizing the risk of RF-related lead heating and myocardial thermal injury limitation by limiting the SAR to 2.0 W/kg; 2) reprogramming the ICD with deactivation of therapy delivery; 3) reprogramming the ICD to VVI pacing with the lowest possible lower rate limit; 4) continuous monitoring of electrocardiogram and pulse oximetry; 5) presence of an electrophysiologist and full resuscitation facilities at the MRI site; 6) ICD interrogation immediately after MRI to exclude clinically relevant changes in the technical and functional ICD parameters; and 7) exclusion of PM-dependent ICD patients. Utilizing these ICD, MRI, and monitoring-related safety precautions, we did not observe any damage to the ICD systems, any unexpected changes in heart rate or rhythm, any attempted therapy delivery, or any evidence for RF-related myocardial thermal damage during or after MRI. Therefore, we believe that in selected patients with an urgent clinical need to undergo MRI in the absence of an alternative imaging modality, MRI in patients with ICDs at 1.5-T carries an acceptable benefit/risk ratio.
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Footnotes
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Dr. Litt has received research grants from Siemens Medical Solutions (Malvern, Pennsylvania). Dr. Schwab is a consultant to Medtronic (Minneapolis, Minnesota) and St. Jude Medical (St. Paul, Minnesota). Dr. Sommer is a consultant to Medtronic (Minneapolis, Minnesota).
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References
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1. Naehle CP, Sommer T, Meyer C, et al. Strategy for safe performance of magnetic resonance imaging on a patient with implantable cardioverter defibrillator Pacing Clin Electrophysiol 2006;29:113-116.[CrossRef][Medline]2. Wollmann C, Grude M, Tombach B, et al. Safe performance of magnetic resonance imaging on a patient with an ICD Pacing Clin Electrophysiol 2005;28:339-342.[CrossRef][Medline] 3. Roguin A, Donahue JK, Bomma CS, Bluemke DA, Halperin HR. Cardiac magnetic resonance imaging in a patient with implantable cardioverter-defibrillator Pacing Clin Electrophysiol 2005;28:336-338.[CrossRef][Medline] 4. Gimbel JR, Kanal E, Schwartz KM, Wilkoff BL. Outcome of magnetic resonance imaging (MRI) in selected patients with implantable cardioverter defibrillators (ICDs) Pacing Clin Electrophysiol 2005;28:270-273.[CrossRef][Medline] 5. Nazarian S, Roguin A, Zviman MM, et al. Clinical utility and safety of a protocol for noncardiac and cardiac magnetic resonance imaging of patients with permanent pacemakers and implantable-cardioverter defibrillators at 1.5-Tesla Circulation 2006;114:1277-1284.[Abstract/Free Full Text] 6. Roguin A, Schwitter J, Vahlhaus C, et al. Magnetic resonance imaging in individuals with cardiovascular implantable electronic devices Europace 2008;10:336-346.[Abstract/Free Full Text] 7. Levine GN, Gomes AS, Arai AE, et al. Safety of magnetic resonance imaging in patients with cardiovascular devices: an American Heart Association scientific statement from the Committee on Diagnostic and Interventional Cardiac Catheterization, Council on Clinical Cardiology, and the Council on Cardiovascular Radiology and Intervention: endorsed by the American College of Cardiology Foundation, the North American Society for Cardiac Imaging, and the Society for Cardiovascular Magnetic Resonance Circulation 2007;116:2878-2891.[Abstract/Free Full Text] 8. Becker R, Ruf-Richter J, Senges-Becker JC, et al. Patient alert in implantable cardioverter defibrillators: toy or tool? J Am Coll Cardiol 2004;44:95-98.[Abstract/Free Full Text] 9. Roguin A, Zviman MM, Meininger GR, et al. Modern pacemaker and implantable cardioverter/defibrillator systems can be magnetic resonance imaging safe: in vitro and in vivo assessment of safety and function at 1.5-T Circulation 2004;110:475-482.[Abstract/Free Full Text] 10. Haverkamp W, Hindricks G, Gulker H, et al. Coagulation of ventricular myocardium using radiofrequency alternating current: bio-physical aspects and experimental findings Pacing Clin Electrophysiol 1989;12:187-195.[CrossRef][Medline] 11. Nordbeck P, Weiss I, Ehses P, et al. Measuring RF-induced currents inside implants: impact of device configuration on MRI safety of cardiac pacemaker leads Magn Reson Med 2009;61:570-578.[CrossRef][Web of Science][Medline] 12. Sommer T, Naehle CP, Yang A, et al. Strategy for safe performance of extrathoracic magnetic resonance imaging at 1.5-Tesla in the presence of cardiac pacemakers in non-pacemaker-dependent patients: a prospective study with 115 examinations Circulation 2006;114:1285-1292.[Abstract/Free Full Text] 13. Luechinger R, Duru F, Zeijlemaker VA, Scheidegger MB, Boesiger P, Candinas R. Pacemaker reed switch behavior in 0.5, 1.5, and 3.0 tesla magnetic resonance imaging units: are reed switches always closed in strong magnetic fields? Pacing Clin Electrophysiol 2002;25:1419-1423.[CrossRef][Medline] 14. Luechinger R, Duru F, Candinas R, Boesiger P. Safety considerations for magnetic resonance imaging of pacemaker and ICD patients Herzschr Elektrophys 2004;15:73-81.[CrossRef] 15. Roguin A, Zviman MM, Meininger GR, et al. Modern pacemaker and implantable cardioverter/defibrillator systems can be magnetic resonance imaging safe: in vitro and in vivo assessment of safety and function at 1.5-T (reply) Circulation 2005;111:e434. 16. Rasmussen MJ, Friedman PA, Hammill SC, Rea RF. Unintentional deactivation of implantable cardioverter-defibrillators in health care settings Mayo Clin Proc 2002;77:855-859.[Abstract/Free Full Text] 17. Larsen MP, Eisenberg MS, Cummins RO, Hallstrom AP. Predicting survival from out-of-hospital cardiac arrest: a graphic model Ann Emerg Med 1993;22:1652-1658.[CrossRef][Web of Science][Medline] 18. Valenzuela TD, Roe DJ, Cretin S, Spaite DW, Larsen MP. Estimating effectiveness of cardiac arrest interventions: a logistic regression survival model Circulation 1997;96:3308-3313.[Abstract/Free Full Text] 19. Gradaus R, Bode-Schnurbus L, Weber M, et al. Effect of ventricular fibrillation duration on the defibrillation threshold in humans Pacing Clin Electrophysiol 2002;25:14-19.[CrossRef][Medline]
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Abstract
Methods