MRI-conditional Pacemaker System Research Articles

The cumulative effects and clinical safety of repeat magnetic resonance imaging on an MRI-conditional pacemaker system at 1.5 tesla.

BackgroundStudies have demonstrated magnetic resonance imaging (MRI) safety in the presence of MRI-conditional permanent pacemakers (PPM). However, since patients’ care may require serial MRIs, it is necessary to evaluate device safety and performance after multiple scans.ObjectivesWe evaluated safety and performance of MRI-conditional PPMs after serial MRIs over various anatomic regions performed during a multicenter, prospective, single-arm study (ProMRI).MethodsProMRI was a multiphase observational study designed to evaluate PPM performance after MRI scans. Our study evaluated PPM function in a cohort of patients who underwent multiple 1.5-T MRI scans. Selected patients underwent separate head, chest, and lumbar spine MRIs. Pacing capture threshold (PCT), lead impedance (LI), sensing amplitude, and battery capacity were collected before and after scanning. Freedom from serious adverse device effects (SADE) through 1 month post MRI served as a primary endpoint. Changes in PPM function parameters, including threshold success rate and sensing attenuation, were analyzed for statistical significance and clinical relevance.ResultsIn 81 patients no adverse events or SADE occurred. Statistically significant changes in ventricular PCT (0.034 ± 0.15 V) immediately after, ventricular LI immediately after (-18.7 ± 44.2 Ω) and 1 month post phase B (-19.8 ± 44.9 Ω), and atrial sensing attenuation immediately after (-0.27 ± 0.92 mV) and 1 month post phase B (-0.22 ± 0.92 mV) were noted. However, these changes were not clinically relevant in degree.ConclusionThese results demonstrate the safety and performance of the ProMRI PPM in patients undergoing 3 serial MRIs over various anatomic regions.

MR feature tracking in patients with MRI-conditional pacing systems: The impact of pacing.

To develop feature tracking (FT) software to perform strain analysis on conventional (nontagged) cardiac magnetic resonance imaging (MRI) function images. With the advent of MRI-conditional pacemaker systems, effects of cardiac pacing on myocardial strain can be studied using MR. In this study the impact of pacing on left ventricular (LV) strain was investigated using MR-FT in patients with an MRI-conditional cardiac implantable electronic device (CIED). FT was performed on 32 1.5T MR studies (16 patients with an MRI-conditional CIED and 16 control patients with normal scans). Short- and long-axis steady state free precession (SSFP) cines were used for the FT analysis. Strain was assessed using CVI(42) software (Circle Cardiovascular Imaging, Alberta, Canada). In addition, the intra- and interobserver variability was determined using the intraclass correlation coefficient. Of the 16 patients with an MRI-conditional CIED, five patients were paced during the MRI exam. Despite the occasional presence of susceptibility artifacts induced by the CIED, radial, circumferential, and longitudinal strain parameters could be derived for all patients. Peak radial strain and peak circumferential strain were reduced during pacing when compared to the control group; for radial strain: 20.1 ± 4.7% vs. 33.1 ± 6.9%, P < 0.001, and for circumferential strain -7.5 ± 3.5% vs. -14.9 ± 3.2%, P < 0.05. Peak strain parameters were reproducible on an intra- and interobserver level. MR-FT is feasible in patients with an MRI-conditional CIED and can be used to quantify regional wall motion. J. MAGN. RESON. IMAGING 2016;44:964-971.

The cumulative effects and clinical safety of repeat magnetic resonance imaging on an MRI-conditional Pacemaker system at 1 .5 Tesla

The cumulative effects and clinical safety of repeat magnetic resonance imaging on an MRI-conditional Pacemaker system at 1 .5 Tesla

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

BackgroundWith 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.MethodsTen 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.ResultsFor 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.ConclusionsIn conclusion, the combined MRI and IPM method is clinically applicable and can identify sites of earliest depolarization with a clinically useful accuracy.Electronic supplementary materialThe online version of this article (doi:10.1007/s10840-015-0054-9) contains supplementary material, which is available to authorized users.

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

IntroductionIn 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.MethodsComputer 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.ResultsThe 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.ConclusionThis study demonstrated the feasibility of deriving detailed anterior epicardial potential information using only 62 torso electrodes without the use of an a priori model.Electronic supplementary materialThe online version of this article (doi:10.1007/s00392-015-0891-7) contains supplementary material, which is available to authorized users.

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

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. 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. 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.

MRI Conditionally Safe Pacemakers

MRI scans of conventional (not MRI-conditional) pacemakers and implantable cardioverterdefibrillators (ICDs) can be performed safely under specific conditions in a controlled environment. MRI scanning of patients with pacemaker or ICD systems should be undertaken using a multidisciplinary approach that requires personnel trained in device management and advanced cardiac life support, availability of resuscitation equipment and facilities, and a thorough discussion of risk and benefits between patient and physician. MRI-conditional pacemaker systems have been redesigned to mitigate electromagnetic interference and heating. The safety of MRI in the setting of cardiac implantable electronic devices has been studied mainly using standard scanners with field strength of 1.5-T; therefore, the safety protocols should not be extrapolated to scanners with different field strengths or configurations, such as 3-T and open bore systems.

Preliminary Results of CMR in Nine Patients with Congenital Heart Disease and MRI-Conditional Pacemaker Systems

Preliminary Results of CMR in Nine Patients with Congenital Heart Disease and MRI-Conditional Pacemaker Systems

IRM cardiaque avec un stimulateur IRM compatible

Patients with cardiac implantable electronic devices are usually excluded from MRI examinations due to contraindication for MRI. The MRI-conditional pacemaker system may allow the benefits of MRI (system 1.5T) to be more accessible to pacemaker patients. A 62-year-old man was admitted with acute coronary syndrome and atrial fibrillation. A conventional angiography showed normal coronaries. A cardiac cardioversion revealed a significant sinus node dysfunction and a magnetic resonance imaging (MRI) compatible dual chamber system was implanted. At 6-week follow-up, a cardiac MRI revealed a typical anterior myocardial infarction with diagnostic quality images despite pacemaker. This is one of the first reports of cardiovascular MRI in a patient with MRI-conditional pacing system.

Cardiac magnetic resonance in a patient with MRI-conditional pacemaker

An implanted pacemaker is generally considered a contraindication for magnetic resonance imaging (MRI). The increasing number of indications for MRI and the rising prevalence of implanted cardiac pacemakers have prompted the recent development of MRI-conditional pacemaker systems.We present the case of a 68-year-old woman with left ventricular hypertrophy, hypertension, aortic valve stenosis and a family history of cardiac amyloidosis, who developed complete heart block. In view of the foreseeable need for cardiac MRI, an MRI-conditional dual chamber pacemaker was implanted. The MRI scan confirmed moderate left ventricular hypertrophy and aortic valve stenosis, and showed no delayed enhancement suggestive of amyloid heart disease. This case illustrates the feasibility of cardiac MRI in this setting and the usefulness of the recently introduced MRI-conditional pacemaker systems.

Cardiac magnetic resonance in a patient with MRI-conditional pacemaker

An implanted pacemaker is generally considered a contraindication for magnetic resonance imaging (MRI). The increasing number of indications for MRI and the rising prevalence of implanted cardiac pacemakers have prompted the recent development of MRI-conditional pacemaker systems.We present the case of a 68-year-old woman with left ventricular hypertrophy, hypertension, aortic valve stenosis and a family history of cardiac amyloidosis, who developed complete heart block. In view of the foreseeable need for cardiac MRI, an MRI-conditional dual chamber pacemaker was implanted. The MRI scan confirmed moderate left ventricular hypertrophy and aortic valve stenosis, and showed no delayed enhancement suggestive of amyloid heart disease. This case illustrates the feasibility of cardiac MRI in this setting and the usefulness of the recently introduced MRI-conditional pacemaker systems.

MRI in patients with cardiac implantable electronic devices

MRI is a powerful diagnostic tool; however, it is relatively contraindicated for patients with cardiovascular implantable electronic devices (CIEDs) such as pacemakers and implantable defibrillators. Several interactions with CIEDs have the potential to cause harm, and fatalities have been reported. Limited experience of MRI in patients with CIEDs under close supervision and utilizing specific scanning protocols has emerged from a small number of centers. Even then, adverse effects on the CIED have been reported. The recent development of MRI-conditional pacemaker systems and the demonstration of safe magnetic resonance scanning in a large clinical trial (EnRhythm MRI™ SureScan™ Pacing System Study) is a significant advance in the care of patients with CIEDs, opening up this important imaging modality to those previously denied it. Further development of MRI-conditional CIEDs, including implantable cardioverter-defibrillators, is expected but presents many technological challenges.