Takeshi Toyoshima

A Novel Assessment Methodology for the EMI Occurrence in Implantable Medical Devices Based Upon Magnetic Flux Distribution of RFID Reader/writers

With respect to the EMI affecting implantable medical devices caused by radio frequency identification reader/writers (RFID R/W), experimental investigations are conducted to develop a risk assessment methodology based upon the measurement of the EMF distribution around RFID R/W. First, fundamental EMI occurrence mechanisms of implantable- cardiac pacemakers and -cardioverter-defibrillators (ICD) are described. Secondly, the characteristics of the radio wave emitted by the RFID R/W are described. Next, EMI test experiments and measurements of the field distributions are performed. Then, a novel experimental assessment methodology is proposed. The EMI characteristics derived from magnetic flux distributions are compared with the experimental results to confirm the effectiveness of the proposed methodology. Finally, it is shown that the probability of EMI occurrence can be estimated using the statistical processing of the proposed methodology.

In vitro Assessment of Electromagnetic Interference due to Low-Band RFID reader/writers on Active Implantable Medical Devices

Introduction: The electromagnetic interference (EMI) of active implantable medical devices (AIMDs) due to 125–135 kHz and HF (13.56MHz) radio‐frequency identification (RFID) reader/writers are discussed based on in vitro experiments. The purpose of this paper is to clarify the detailed EMI occurrence conditions of both implantable cardiac pacemakers and implantable cardioverter defibrillators (ICDs) when used in proximity to commercial lowband RFID reader/writers.

Investigation of optimal position for implantable loop recorders by potential mapping with Reveal DX.

Electrode positioning is important for the operation of implantable loop recorders (ILRs). This study aimed to investigate optimal electrode positions for the implantation of ILRs.

An experimental validation of a detailed numerical model for predicting implantable medical devices EMI due to low-band RFID reader/writers

The numerical assessment methodology of RFID/IMD-EMI was confirmed based on the result of the in-vitro experiments and the numerical analyses. The maximum interference distances obtained by the experiments and the FDTD analysis agreed very well. The good repeatability of the experiments and detailed modeling in the analyses achieve this high accuracy estimation. These results clarify the interference voltages due to the magnetic field generated around the low-band RFID reader/writer and they can be estimated by using precise and detailed analysis.

Practical method to evaluate electromagnetic interference in active implantable medical devices

It is known that some of external electromagnetic fields cause interference (EMI) to an active implantable medical device (AIMD) such as a cardiac pacemaker. Therefore it is important to establish a method to evaluate whether a particular electromagnetic environment would cause EMI to the AIMD or not. For this evaluation, the AIMD should be placed in a human body model, which is a kind of a saline tank. However, if the AIMD handles more than one chamber of the heart, signal leakage between the chambers comes up in the human body model. And it becomes difficult to monitor the output from only one chamber and to inject a simulated cardiac signal (EGM) only to the intended chamber. The author had worked out a new electrode that can reduce signal leakage of the output to less than 4 %, and injected EGM leakage to less than 3%, whereas the output leakage is 44% and the EGM leakage is 71% by another commonly-used method.

Measurement of body surface energy leakage of defibrillation shock by an implantable cardioverter defibrillator.

NIWANO, S., et al.: Measurement of Body Surface Energy Leakage of Defibrillation Shock by an Implantable Cardioverter Defibrillator. Leakage of electrical current from the body surface during a defibrillation shock delivery by an ICD device was evaluated in 27 patients with life‐threatening ventricular tachyarrhythmias. All patients underwent the implantation of the Medtronic Jewel Plus ICD system, and the defibrillation shocks were delivered between the active can implanted in the left subclavicular region and the endocardial lead placed in the right ventricle. At the time of measurement of the effect of electrical energy delivery for defibrillation, the shocks were delivered in a biphasic form at the energy level of 20 or 30 J. During each delivery of the defibrillation shock, the electrical current to the body surface was measured through large skin electrodes (6.2 cm2) that were pasted at the following positions: (1) parallel position: the electrodes were placed at the left shoulder and the right low‐chest, and the direction of the electrode vector was parallel to the direction of the defibrillation energy flow, and (2) cross position: the electrodes were placed at the right shoulder and the left low‐chest, and the vector of the electrodes was roughly perpendicular to the direction of the energy flow. The energy leakages were measured in 80 defibrillation shocks. The peak leakage current during the shock delivery at energy of 30 J was 48 ± 26 mA at the parallel position and 19 ± 15 mA at the cross position (P = 0.0002). The energy leakage at a 30‐J shock was 7.4 ± 7.2 mJ at the parallel position and 1.4 ± 2.3 mJ at the cross position (P = 0.0002). The actual maximum energy leakage was 105 mA, 29 mJ, and 106 V that appeared at the parallel position. The body surface leakage of the defibrillation energy of the ICD device was evaluated. The power of the energy leakage strongly depended on the angle between the alignment of the recording electrodes and the direction of the energy flow. The highest current leakage to the body surface reached a considerable level, but the energy leakage was small because of the short duration of the defibrillation shock.

Significant impact of electrical storm on mortality in patients with structural heart disease and an implantable cardiac defibrillator

BACKGROUND Electrical storm (E-Storm), defined as multiple episodes of ventricular arrhythmias within a short period of time, is an important clinical problem in patients with an implantable cardiac defibrillator (ICD) including cardiac resynchronization therapy devices capable of defibrillation. The detailed clinical aspects of E-Storm in large populations especially for non-ischemic dilated cardiomyopathy (DCM), however, remain unclear. OBJECTIVE This study was performed to elucidate the detailed clinical aspects of E-Storm, such as its predictors and prevalence among patients with structural heart disease including DCM. METHODS We analyzed the data of the Nippon Storm Study, which was a prospective observational study involving 1570 patients enrolled from 48 ICD centers. For the purpose of this study, we evaluated 1274 patients with structural heart disease, including 482 (38%) patients with ischemic heart disease (IHD) and 342 (27%) patients with DCM. RESULTS During a median follow-up of 28months (interquartile range: 23 to 33months), E-Storm occurred in 84 (6.6%) patients. The incidence of E-Storm was not significantly different between patients with IHD and patients with DCM (log-rank p=0.52). Proportional hazard regression analyses showed that ICD implantation for secondary prevention of sudden cardiac death (p=0.0001) and QRS width (p=0.015) were the independent risk factors for E-storm. In a comparison between patients with and without E-Storm, survival curves after adjustment for clinical characteristics showed a significant difference in mortality. CONCLUSION E-Storm was associated with subsequent mortality in patients with structural heart disease including DCM.

Active implantable medical device EMI assessments for electromagnetic emitters operating in various RF bands

This paper describes the electromagnetic interference (EMI) characteristics of active implantable medical devices based on assessments of Radio Frequency Identification interrogators. Typical examples of interrogators operating in various RF bands are tested to estimate the EMI experienced by implantable-cardiac pacemakers and -cardioverter-defibrillators. The EMI occurrence mechanism and some experimental EMI evaluation results for typical devices are shown. Observed characteristics of the EMI are discussed based upon the transmission radio wave specifications. This discussion can give a good perspective on the same EMI issue raised by wireless power transmission systems.

Is the pace/sense conductor related to a high voltage short circuit in a dual coil ICD system? An experimental study

We carried out a bench study of implantable cardioverter‐defibrillator (ICD) performance in order to investigate whether the right ventricular (RV) ring contributes to the occurrence of a high‐voltage (HV) short circuit.