IntroductionElectromagnetic interferences with automatic

implantable cardioverter defibrillators (ICDs)have been documented for several devices as elec-tronic article surveillance systems,1 slot ma-chines,2 electric razors,3 or hand held radiofre-quency remote controls.4 Usually, those kind ofinterferences are easy to recognize in the storedelectrograms (EGMs) of ICDs due to the typicalpattern of electrical noise.

Case ReportAn ICD (Medtronic model 7221 [Minneapolis,

MN, USA] and integrated bipolar Sprint electrode6942) were implanted in a 56-year-old man whosuffered symptomatic ventricular tachycardias(VTs). The ICD was programmed with VT (400 ms,NID 5 16) and ventricular fibrillation (VF) (300ms, NID 5 18/24) zones, antitachycardia pacing(ATP), and defibrillation shocks. Sensitivity wasprogrammed to 0.3 mV after testing correct VF de-tection at 1.2 mV during the implant.

During the 8 months following ICD implanta-tion, the patient was followed-up regularly, andhe had multiple and appropriate ATP treatmentsdue to VT but no shocks due to VF. Usual episodesin this patient were noticed as palpitations fol-lowed by immediate cessation.

The patient came to the hospital complaining

of a shock without warning symptoms of any kind.After interrogation of the device, the ICD dis-played a detected episode classified as VF and a24-J shock was delivered. Analyzing the EGM andevent marker of the episode (Fig. 1), a pattern ofelectrical noise was observed. Impedance of thelead was normal, similar to all previous follow-ups (53 ohms for high voltage impedance), andsensing after the episode was correct (no morenoise observed). The patient explained that theshock was delivered when he was at home in thelaundry room. He was there getting the clothes,and he felt the shock just when he touched thewashing machine. As it was not grounded andthere was no evidence of lead failure, an electricalleak from the washing machine causing 50-Hz in-terference was inferred (alternating current [AC]in Spain has a voltage of 220 V and a frequency of50 Hz). After the episode, the washing machinewas repaired with a grounding plug and the pa-tient did not suffer more inappropriate shocks.

CommentsIn this case, a typical pattern of sensed noise

(three sensed and one undersensed) is observed:after a R wave sense, there is a delay before thenext sensed noise because of the automatic au-toadjusting sensitivity threshold mechanism(which increases sensitivity up to 75% of the EGMpeak after a sensed event), as shown in the eventmarker. This does not happen in a real VF, wherenearly all waves are sensed, because differencesbetween waves are not so important.

ConclusionsThe authors conclude that the washing ma-

chine had an electric leak (interference seen in the

Washing Machine Associated 50 Hz Detected AsVentricular Fibrillation by An ImplantedCardioverter DefibrillatorXAVIER SABATÉ,* CRISTINA MOURE,* JOAN NICOLÁS,* MIQUEL SEDÓ,†and XAVIER NAVARRO‡From the *Ciutat Sanitaria I Universitaria de Bellvitge, Barcelona, †Tachyspecialist, MedtronicIbérica, and the ‡Scientific and Clinical Department, Medtronic Ibérica, Spain

SABATÉ, X., ET AL.: Washing Machine Associated 50 Hz Detected As Ventricular Fibrillation by An Im-planted Cardioverter Defibrillator. This case report describes a patient with an automatic ICD who suf-fered a defibrillation shock without warning symptoms. An electrical interference can be observed in thestored EGM of the episode. The patient explained that the moment he felt the shock he was touching awashing machine. After correct grounding of this machine the patient did not suffer more inappropriateshocks. (PACE 2001; 24:1281–1283)

implantable defibrillators, interference, electrical noise.

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Address for reprints: Xavier Sabaté, M.D., Unitat d’Arritmies.Ciutat Sanitària I Universitària de Bellvitge, Feixa Llarga s/n,08907 Hospitalet de Llobregat, Barcelona, Spain. Fax: 134-93-2607619.

Received April 4, 2000; revised September 12, 2000; acceptedSeptember 22, 2000.

Reprinted with permission fromJOURNAL OF PACING AND CLINICAL ELECTROPHYSIOLOGY , Volume 24, No. 8, August 2001

Copyright © 2000 by Futura Publishing Company, Inc., Armonk, NY 10504-0418.

SABATÉ, ET AL.

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Figure 1. (A) Episode report, detection settings and therapy data. (B) The patient comes in thelaundry room. Electrical noise is seen on the ventricular electrogram. (C) The patient gets closerto the washing machine. The amplitude of the interference becomes bigger. (D) The patient touchesthe washing machine. The interference is large enough to be sensed by the detection circuit. TheFib Detection Criteria is fulfilled and therapy delivered. The shock moves the patient away fromthe interference field and he jumps out of the room.

registration), and that right after the shock the pa-tient was no longer near the washing machine.The main problem of noise sensing and VF inter-pretation are inappropriate shocks that affect thepatient’s quality-of-life. In Spain, the impositionof grounding plugs for home electrical applianceis quite recent, and many old houses still do nothave them. This episode emphasizes the need toadvise patients with an ICD to have correctlygrounded electrical equipment.

References1. Mathew P, Lewis C, Neglia J, et al. Interaction between electronic ar-

ticle surveillance systems and implantable defibrillators: Insightsfrom a fourth generation ICD. PACE 1997; 20:2857–2859.

2. Madrid A, Sanchez A, Bosch E, et al. Dysfunction of implantable de-fibrillators caused by slot machines. PACE 1997; 20:212–214.

3. Seifert T, Block M, Borggrefe M, et al. Erroneus discharge of an im-plantable cardioverter defibrillator caused by an electric razor.PACE 1995; 18:1592–1594.

4. Man KC, Davidson T, Langberg JJ, et al. Interference from a handheld radiofrequency remote control causing discharge of an im-plantable defibrillator. PACE 1993; 16:1756–1758.

FALSE VF BY WASHING MACHINE

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