Do we need pacemakers resistant to magnetic resonance imaging?

Irnich, Werner; Irnich, Burkhard; Bärtsch, Christine; Stertmann, W. A.; Gufler, Hubert; Weiler, G

doi:10.1016/j.eupc.2005.02.120

Cited by 134 publications

(104 citation statements)

References 14 publications

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“…Measurements with a "pacemaker patient simulation model" (described in Ref. 15) in am MRI machine with isolated sinusoidal gradients showed that the waveform is no half sinus wave, as expected under steady state conditions, but resembles a sinus square pulse probably due to the limited frequency response of the gradient coil. Figure 5 demonstrates the waveshape of the induced voltage measured in a 1.5T MRI machine (Philips Gyroscan, Philips Medical Systems, Best, The Netherlands).…”

Section: Investigation Of Experimental Resultsmentioning

confidence: 99%

Stimulation threshold comparison of time‐varying magnetic pulses with different waveforms

Irnich¹,

Hebrank²

2008

Magnetic Resonance Imaging

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Purpose: To clarify whether sinusoidal pulses possess lower thresholds than rectangular ones at perception threshold, a statement often made that contradicts the theory of stimulation. Materials and Methods:The results of a nerve stimulation study with 65 volunteers and with trapezoidal and sinusoidal gradient pulses were used to apply the combination of the electric field, induced in the tissue of the human body, with the "Fundamental Law of Electrostimulation." This law claims that the waveshape of a pulse is not essential as long as the amplitude of the pulse does not decrease below rheobase (rheobase condition). Results:If the rheobase condition is applied to sinusoidal waveforms and the pulse duration and amplitude is corrected accordingly, both trapezoidal and sinusoidal gradient pulses have identical threshold amplitudes as a function of pulse duration. Conclusion:The "Fundamental Law of Electrostimulation," including the "rheobase condition," proved to be a good basis for describing magnetic field stimulation (magnetostimulation) and that application of it to magnetostimulation is suitable as the basis for describing magnetic field stimulation with various waveforms. For nonrectangular pulses, pulse durations and pulse amplitudes must be corrected according to the "rheobase condition." The exponential Blair Equation is less suited to be applied in magnetostimulation. NATIONAL AND INTERNATIONAL BODIES have discussed possible hazards due to gradient switching in magnetic resonance imaging (MRI) systems and have formulated limiting exposure levels of magnetic fields (1). KeyHowever, there is still interest in understanding the process of stimulation in human subjects exposed to timevarying magnetic fields as they are used in MRI. The need to avoid painful peripheral nerve stimulation (PNS) or, even worse, cardiac stimulation, due to rapidly switched magnetic fields sets an upper limit on the magnetic field gradient strengths that can be employed in fast MRI. It is generally recognized that in whole-body imaging the ygradient coil causes PNS at the lowest rates of gradient change (2,3). A search of the literature of which electric fields can stimulate the heart revealed that the rheobase field strength of the heart for single monophasic stimuli is Ϸ60 V/m (4), and thus, 10 times higher than the lowest assumed threshold for 20 m diameter nerves with 6.2 V/m (5). Due to the fact that cardiac magnetostimulation has not yet been reported in humans and is not expected with the hardware currently available, the following considerations are focused on PNS, the first sensations that appear in whole-body MRI.Since publication of our first article on electrostimulation by time-varying magnetic fields (4), it is mostly accepted in the MRI literature that it is the electric field and not the current density that is responsible for magnetostimulation and that there is a hyperbolic relationship between pulse duration and the electric field characterized by the terms rheobase and chronaxie as they were introduced by Lapicq...

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Section: Investigation Of Experimental Resultsmentioning

confidence: 99%

Stimulation threshold comparison of time‐varying magnetic pulses with different waveforms

Irnich¹,

Hebrank²

2008

Magnetic Resonance Imaging

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“…There are only individual reports of complications from case reports of patients who underwent an MR examination without specific safety precautions because the physician was unaware of the presence of a pacemaker/ICD system. This includes at least 7 cases with a fatal outcome [28]. Both the true number of MR-related complications and the reference value, namely the total number of patients who underwent such an "accidental" MR examination, are not known.…”

Section: Introductionmentioning

confidence: 99%

MR Imaging in Patients with Cardiac Pacemakers and Implantable Cardioverter Defibrillators

Sommer

Bauer

Fischbach

et al. 2017

Fortschr Röntgenstr

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▪ MR conditional pacemaker and ICD systems have been tested and approved for MR examination under specific conditions ("in-label" use). Precise understanding of and compliance with the terms of use for the specific pacemaker system are essential for patient safety. ▪ The risk for an ICD patient during MR examinations is to be considered significantly higher compared to PM patients due to the higher vulnerability of the structurally damaged myocardium and the higher risk of irreversible damage to conventional ICD systems.The indication for a MR examination of an ICD patient should therefore be determined on a stricter basis and the expected risk/ benefit ratio should be critically reviewed. ▪ This complex subject requires close collaboration between radiology and cardiology.

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“…Le domaine hospitalier est très particulier : chirurgie (bistouri électrique, ablathérapie), imagerie médicale (IRM), thérapie par stimulation électromagnétique, monitoring... De nombreuses investigations ont été menées sur l'IRM (Achenbach et al, 1997 ;Irnich et al, 2005), qui est devenu un moyen de diagnostic quotidien. Cependant, la présence d'un implant est considérée comme une contre-indication à ce type d'imagerie, contre-indication qui commence à être remise en cause dans un esprit d'évaluation bénéfice/risque du patient.…”

Section: L'environnement Médico-hospitalierunclassified

Implants médicaux et champs électromagnétiques basses fréquences 0–100 kHz

Kourtiche

Nadi

Souques³

et al. 2014

Radioprotection

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Résumé -Présents dans notre environnement les rayonnements électromagnétiques (EM) suscitent de multiples questions quant à leurs effets potentiels pour les porteurs de dispositifs médicaux actifs implantés (DMAI). Le nombre croissant de porteurs d'implants médicaux, y compris dans la population active, a entraîné un questionnement quant à leur comportement en présence d'un champ EM. L'interaction entre le corps humain et les champs EM reste complexe et dépend de multiples facteurs tels que la fréquence, la puissance et la modulation des champs. Nous présentons ici une revue de cette problématique dans le cas des champs EM basse fréquence. Abstract -Medical implants and low-frequency EM fields 0-100 kHz.Medical implants and low-frequency EM fields 0-100 kHz. Present in our environment, electromagnetic (EM) radiation raises many questions about its potential effects on active implantable medical devices (AIMD). The interaction between EM fields and the human body is complex and depends on multiple factors such as the frequency, power and modulation of the fields. The growing number of people with medical implants, including workers, has led to questions about their behavior in the presence of an EM environment. We present here a review of this issue in the case of low-frequency exposure.

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Do we need pacemakers resistant to magnetic resonance imaging?

Cited by 134 publications

References 14 publications

Stimulation threshold comparison of time‐varying magnetic pulses with different waveforms

Stimulation threshold comparison of time‐varying magnetic pulses with different waveforms

MR Imaging in Patients with Cardiac Pacemakers and Implantable Cardioverter Defibrillators

Implants médicaux et champs électromagnétiques basses fréquences 0–100 kHz

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