Herzschr Elektrophys 17:137–139 (2006) DOI 10.1007/s00399-006-0527-8

H. Nägele M. Azizi

Received: 10 December 2005 Accepted after revision: 15 March 2006

CASE REPORT

Inappropriate ICD discharge induced by electrical interference from a physio-therapeutic muscle stimulation device

Inadäquate ICD-Schockabgabe durch elektromagnetische Interferenz mit einem physiotherapeutischen Muskelstimulator " Zusammenfassung Dieser Bericht stellt den Fall eines Patienten dar, der während einer Reizstromanwendung im Lendenbereich im Rahmen einer Physiotherapie eine Schocktherapie durch seinen implantierten Cardioverter-Defibrillator (ICD) erhalten hat. Die Analyse des gespeicherten Elektrogramms zeigt, dass es sich um eine inadäquate Therapie durch elektromagnetische Interferenz mit dem Reizstrom gehandelt hat. Auf diese mögliche Interaktion sollten sowohl Patienten mit einem ICD, als auch Physiotherapeuten im Vorfeld hingewiesen werden. " Schlüsselwörter Elektromagnetische Interferenz – inadäquate ICD-Therapie – implantierbarer Cardioverter-Defibrillator

Priv.-Doz. Dr. H. Nägele ()) Dr. M. Azizi St. Adolfstift Medical Clinic Hamburger Str. 41 21465 Reinbek, Germany

Since the introduction of special detection algorithms, inappropriate implantable cardioverter defibrillator (ICD) shocks induced by intrinsic cardiac signals (for example due to supraventricular arrhythmia, T-wave sensing etc.) have been reduced in the new device generation [3]. Due to a significant increase in the utilization

" Summary This report illustrates the case of a patient with an implantable cardioverter defibrillator (ICD) who during physiotherapy with transcutaneous electrical stimulation of the lumbar musculature perceived a shock discharge by the ICD. Analysis of the stored electrogram showed inappropriate therapy due to electromagnetic interference with the external stimulation. Patients as well as physiotherapists should be informed about this potential interaction to avoid such iatrogenic, inappropriate ICD therapy. " Key words Electromagnetic interference – inappropriate ICD therapy – implantable cardioverter defibrillator

of electrical devices in daily life, external signals by electromagnetic interference (EMI) may become increasingly important. Oversensing of EMI is facilitated by the automatic sensitivity adjustment algorithms, a basic function of implantable defibrillation devices to detect ventricular fibrillation with very small potentials.

The incidence of ICD malfunction induced by EMI seems to be in the range of about 1% per year and patient [1]. As potential causes of ICD discharges induced by EMI, regular 50 Hz current, chiropractic treatments and devices for muscle, nerve or sexual stimulation have been described [1, 2, 5]. Even distant sources can transmit electrical

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Fig. 1 Stored ICD electrogram during electromagnetic interference of a muscle stimulation device Abb. 1 Gespeichertes Elektrogramm während einer elektromagnetischen Interferenzepisode zwischen ICD und Reizstromgerät

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Inappropriate ICD discharge induced by electrical interference from a physio-therapeutic muscle stimulation device

signals such as remote cellular phones, remote control of toys, washing machines or fish ponds [4, 7–9]. The individual perception of these preventable, unnecessary and often painful events is usually strong and can disturb the confidence between physicians or other health-care workers and patients. For this reason the awareness on potential sources of EMI and ICDs cannot be overemphasized. We report about a 62 year old male patient with ischemic cardiomyopathy who had received an ICD in 2003 due to recurrent ventricular tachycardia. The device was a single-chamber ICD (Ventak Prizm 2 VR, Guidant Corp., Indianapolis, IN, USA). During the 3 years of follow-up there were 3 episodes of ventricular tachycardias in the VF zone for which appropriate detection was confirmed upon manual review of the stored electrograms and which were treated appropriately with 31 J shocks. The device was programmed to VVI bradycardia pacing at 30 min–1 (3.0 Volt/0.4 ms), detection of ventricular tachyarrhythmia was programmed to 2 zones (VT zone 170–210 min–1, VF-zone > 210

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min–1). The ventricular refractory period was set to 250 ms, sensitivity was left nominal. The intrinsic amplitude at time of implantation was 18 mV and at the time of the last ICD interrogation 8.8 mV. The lead impedance at that time was 691 Ohm with a shock impedance 58 Ohm and a ventricular threshold of 0.8 Volt at 0.4 ms impulse width. Due to lower back pain the patient attended a physiotherapist who applied muscle stimulation therapy in the region of the upper lumbar region. The device used was a Physiomed No. 21 system (PHYSIOMED Elektromedizin AG, Schnaittach/Laipersdorf, Germany). The current was transferred by adhesive electrodes and was set to 40 mA at 50 Hertz. After a short moment of stimulation the patient experienced a defibrillator shock leading to an immediate termination of muscle stimulation. Together with the physiotherapist, the patient immediately attended our outpatient clinic and was interrogated 30 min later. The stored electrogram of the event is shown in the figure. The interference of a 50 Hertz current can easily be recognized. It lead to false positive VF detec-

tion and ultimately to a shock discharge of the defibrillator. A check of defibrillator functions revealed normal values, basically identical to the follow-up two weeks earlier. After information about potential sources of interference and contraindicated medical procedures in patients with an implanted defibrillator, patient and physiotherapist went home. Our case report shows that electrical interference can occur during electrical therapies such as physiotherapeutic muscle stimulation. All medical and paramedical personnel using devices for electrical neuro- or muscular stimulation (e. g. TENS) with a possibility to activate or inhibit implanted electrical cardiac devices such as pacemakers or defibrillators have to be instructed not use this therapy in such a patient population [6]. In cases of doubt, consultation with the follow-up center should be performed. In our opinion, similar to rooms with magnetic resonance imaging, adhesives should be applied to instruments for transcutaneous neuro- or muscular stimulation to prevent their use in patients with implanted pacemakers or defibrillators.

4. Vlay SC (2002) Fish pond electromagnetic interference resulting in an inappropriate implantable cardioverter defibrillator shock. PACE 25:1532 5. Vlay SC (1998) Electromagnetic interference and ICD discharge related to chiropractic treatment. PACE 21:2009 6. Volkmann H (2004) Interference of implanted pacemaker in medical practice. Herzschr Electrophys 15:65–72 7. Sabate X, Moure C, Nicolas J, Sedo M, Navarro X (2001) Washing machine associated 50 Hz detected as ventricular fibrillation by an implanted cardioverter defibrillator. PACE 24:1281–1283

8. Irnich W (1994) A serious case of radiofrequency EMI, when an ICD wearer manipulated a remote control of a toy car. PACE 17:685 9. Fetter JG, Ivans V, Benditt DG, Collins J (1998) Digital cellular telephone interaction with implantable cardioverter-defibrillators. J Am Coll Cardiol. 31:623–628

References 1. Kolb C, Zrenner B, Schmitt C (2001) Incidence of electromagnetic interference in implantable cardioverter defibrillators. PACE 24:465–468 2. Siu CW, Tse HF, Lau CP (2005) Inappropriate implantable cardioverter defibrillator shock from a transcutaneous muscle stimulation device therapy. J Interv Card Electrophysiol 13(1):73–75 3. Gradaus R, Block M, Brachmann J, Breithardt G et al on behalf of the German EURID registry (2003) Mortality, morbidity, and complications in 3344 patients with implantable cardioverter defibrillators. PACE 26:1511–1518

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