Implantable cardioverter-defibrillators (ICDs) are the standard of care for preventing sudden cardiac death in patients who are predisposed to malignant ventricular arrhythmias. Causes of inappropriate ICD shock include equipment malfunction, improper arrhythmia evaluation, misinterpretation of myopotentials, and electromagnetic interference. As the number of implanted ICDs has increased, other contributors to inappropriate therapy have become known, such as minimal electrical current leaks that mimic ventricular fibrillation. We present the case of a 63-year-old man with a biventricular ICD who received 2 inappropriate shocks, probably attributable to alternating-current leaks in a swimming pool. In addition, we discuss ICD sensitivity and offer recommendations to avoid similar occurrences

Angert-Gilman, J.

Goldner, B.

Makaryus, J. N.

Patel, A.

Yacoub, M.

English

PubMed

Hofstra Northwell Academic Works (Hofstra Northwell School of Medicine)

Journal Articles 2014 Inappropriate Implantable Cardioverter-Defibrillator Shocks Attributed to Alternating-Current Leak in a Swimming Pool J. N. Makaryus Hofstra Northwell School of Medicine J. Angert-Gilman Northwell Health M. Yacoub Northwell Health A. Patel Hofstra Northwell School of Medicine B. Goldner Hofstra Northwell School of Medicine Follow this and additional works at: https://academicworks.medicine.hofstra.edu/publications  Part of the Cardiology Commons Recommended Citation Makaryus J, Angert-Gilman J, Yacoub M, Patel A, Goldner B. Inappropriate Implantable Cardioverter-Defibrillator Shocks Attributed to Alternating-Current Leak in a Swimming Pool. . 2014 Jan 01; 41(1):Article 1789 [ p.]. Available from: https://academicworks.medicine.hofstra.edu/publications/1789. Free full text article. This Article is brought to you for free and open access by Donald and Barbara Zucker School of Medicine Academic Works. It has been accepted for inclusion in Journal Articles by an authorized administrator of Donald and Barbara Zucker School of Medicine Academic Works. For more information, please contact academicworks@hofstra.edu. Texas Heart Institute Journal http://dx.doi.org/10.14503/THIJ-12-3005      61© 2014 by the Texas Heart ® Institute, HoustonInappropriate Implant­able Cardioverter­Defibrillator ShocksAttributed to Alternating-Current Leak in a Swimming PoolImplantable cardioverter-defibrillators (ICDs) are the standard of care for preventing sud-den cardiac death in patients who are predisposed to malignant ventricular arrhythmias. Causes of inappropriate ICD shock include equipment malfunction, improper arrhythmia evaluation, misinterpretation of myopotentials, and electromagnetic interference. As the number of implanted ICDs has increased, other contributors to inappropriate therapy have become known, such as minimal electrical current leaks that mimic ventricular fibrillation. We present the case of a 63-year-old man with a biventricular ICD who received 2 inap-propriate shocks, probably attributable to alternating-current leaks in a swimming pool. In addition, we discuss ICD sensitivity and offer recommendations to avoid similar occur-rences. (Tex Heart Inst J 2014;41(1):61-3)I mplantable cardioverter-defibrillators (ICDs) provide primary and secondary pre-vention of sudden cardiac death in patients who are predisposed to malignant ventricular arrhythmias.1-3 Despite the clinical eff icacy and improved technical specifications of newer ICDs, inappropriate shocks can still affect patients who have implanted devices. We review the case of a patient whose inappropriate ICD shocks were most likely caused by the leakage of small amounts of alternating current in a swimming pool.Case ReportA 63-year-old man with a history of atrial fibrillation, coronary artery disease, myo-cardial infarction, multivessel coronary artery bypass grafting, and ischemic cardio-myopathy presented at our electrophysiology clinic for device interrogation. Two months earlier, the patient’s previous permanent pacemaker had been upgraded to a biventricular ICD: a Protecta XT model D314TRG CRT-D (Medtronic, Inc.; Minneapolis, Minn) with battery voltage of 3.1645 V. The atrial lead was a 52-cm Fineline® II EZ Sterox model 4470 (Boston Scientific Corporation; Natick, Mass), implanted in 2008; the right ventricular lead was a 65-cm 6947 Sprint Quattro® (Medtronic), implanted in 2008; and the left ventricular lead was a QuickFlex µ LV, model 1258T (St. Jude Medical, Inc.; St. Paul, Minn), implanted in 2011. The patient had experienced 2 distinct device discharges immediately after jumping into a swimming pool while vacationing in St. Lucia approximately 2 weeks before the current presentation. He described no prodromal symptoms, chest pain, palpitations, dizziness, syncope, or aftereffects. A cardiologist in St. Lucia had ruled out ischemia, heart failure, and electrolyte disturbances. Interrogation of the ICD revealed 2 shocks for electrical activity that the device had interpreted as ventricular fibrillation (Fig. 1). The remainder of the interrogation report revealed normal function, sensing, and evaluation of thresholds by iterative output testing; 3 unrelated episodes of paroxysmal atrial fibrillation had not evoked therapy. The discharges corresponded with the times when the patient was in the swimming pool.CaseReportsJohn N. Makaryus, MDJulia Angert-Gilman, RNMena Yacoub, BSApoor Patel, MDBruce Goldner, MDKey words: Arrhythmias, cardiac/etiology; cardiac pacing, artificial; defibrilla-tors, implantable/adverse effects; electricity/adverse effects; electromagnetic phenomena; electrophysiol-ogy; environmental expo-sure; equipment safety; signal-to-noise ratio; swim-ming poolsFrom: Department of Cardiology, Division of Electrophysiology, North Shore–Long Island Jewish Health System, New Hyde Park, New York 11040Dr. Makaryus is now at the Division of Cardiology, Department of Medicine, Columbia University  Medical Center-New York Presbyterian Hospital,  New York, New York.Address for reprints: Bruce Goldner, MD, Department of Cardiology, North Shore–Long Island Jewish Health System, 270-05 76th Ave., New Hyde Park, NY 11040-1402E-mail: bgoldner@nshs.eduVolume 41, Number 1, 201462      Inappropriate ICD Shocks from Electrical Current Leak in Swimming PoolDiscussionFrom 12% to 21% of ICD patients receive at least one inappropriate shock at some point after device implan-tation. Causes of inappropriate discharge include exter-nal noise, atrial dysrhythmias or oversensing, muscle myopotentials, lead-connector or mechanical faults, and electromagnetic interference (EMI).4 Inappropri-ate discharge for improperly sensed atrial dysrhythmias remains relatively frequent; however, advanced techno-logical specifications used in the production and pro-gramming of newer devices have minimized EMI as a cause of inappropriate discharge. Inappropriate shocks have been associated with ad-verse overall outcomes and decreased quality of life. The occurrence of inappropriate therapy has been associated with a doubled overall mortality rate from proarrhyth-mia, hemodynamic compromise, or the direct mechani-cal effects of the shocks themselves.5 It is therefore crucial to anticipate and optimally avoid possible causes of EMI. Inappropriate therapy attributable to EMI can occur if a mechanically paced patient comes into direct contact with the source emitting the signal, or even if the ICD or PPM is within the source’s electromagnetic field.6 En-vironmental sources of EMI include digital music play-ers and headphones, screening equipment in airports, refrigerators, TASERs, and even casino slot machines. Effects include improper mode-switching, asynchro-nous pacing, and inappropriate antitachycardia pacing or shocks.7 The various types of EMI can be classified in accordance with the frequency of the encountered energy and the electromagnetic field’s strength. Contact with even minimal amounts of electricity can prove hazardous to patients who have a PPM or ICD, especially the latest-generation leads and devices. Homes or recreational facilities might have equipment installed improperly or electrical systems that are not grounded suff iciently to counteract leaking current. Some PPMs and ICDs can detect alternating current as low as 10 µA, depending on their sensitivity settings.8 It is difficult to detect such minute levels of leaking alter-nating current with use of commercial testing devices. In specif ic regard to our patient’s case, the testing of electrical current in a swimming pool might not be rou-tine.6 Few reported cases of inappropriate device therapy have been attributed to electrical current in water. Lee and colleagues6 reported the case of a 70-year-old patient with a Medtronic GEM® model 7227 ICD who was shocked 5 times while swimming in a pool. Garg and associates9 reported the case of a child with left ventricu-lar noncompaction and a Medtronic Micro Jewel II 7223Cx who was shocked inappropriately after entering a swimming pool and once again after using a shower powered by an electric generator. Chan and co-authors10 described 2 cases of inappropriate discharge. The first in-Fig. 1  A) Initial portion of electrogram strip shows substantial noise and electromagnetic interference. The interference corresponds to the time when the patient was in the swimming pool. B) Continuation of electrogram shows noise, interpreted by the device as an intrinsic ventricular signal. C) Continuation of electrogram shows electromagnetic interference, interpreted as ventricular fibrillation and evoking 2 shocks. D) Electrogram shows the termination of electromagnetic interference and resumption of biventricular pacing, most likely corresponding to when the patient was pulled from the swimming pool.  AP = atrial pacing; AR = atrial refractory; BV = biventricular pacing; CD = charge delivered; CE = charge ended; FS = ventricular fibrillation sensed; VS = ventricular-sensedA BC DTexas Heart Institute Journal Inappropriate ICD Shocks from Electrical Current Leak in Swimming Pool      63volved a man with a Medtronic Jewel Plus® Active Can® 7220C who was operating a power drill outdoors in the rain; the other was a man with a Medtronic GEM® II DR model 7271 who touched a washing machine with his wet hand. Of note, all of the abovementioned pa-tients had leads with integrated bipolar sensing. The sensitivity of every ventricular lead was set at 0.3 mV, the lowest possible value. At this setting, newer devices can detect even minimal levels of electrical activity. Bipolar sensing can minimize the effects of EMI. In a true bipolar lead, the defibrillation coil and the ring electrode are separate and have independent conductors. However, in an integrated bipolar lead, the defibrillation coil also serves as the ring electrode, which results in a larger sensing vector (distance from the defibrillation coil to the can). The farther apart the 2 points are from which a device is programmed to collect information, the more susceptible the patient is to EMI.11 Integrated bipolar sensing technology can filter far-field signal po-tentials and focus on local myocardial potentials; how-ever, the gathered information differs because of the altered field of view.12 Despite the differences between integrated and true bipolar sensing, both methods ap-pear to be clinically effective. Currently, most devices are equipped with integrated sensing, as was our patient’s ICD.13 Although increased ICD sensitivity can protect pa-tients who are predisposed to malignant ventricular dysrhythmias, it comes at the price of potentially over-sensing environmental stimuli. Electricity is delivered by means of alternating current, usually at a frequency of 50 to 60 Hz. In our patient, the alternating current was misinterpreted as ventricular fibrillation at an aver-age cycle length of approximately 130 ms. The use of true bipolar sensing can minimize much detection of EMI, but at the cost of a narrower detection vector. Also potentially helpful is the use of an auto-adjusting algo-rithm, as well as auto-gain.12 Further discoveries in this area might minimize day-to-day activity restrictions in patients with implanted devices. Despite all the improvements in device performance, lead technology, and programming that were not fore-seeable even 10 years ago, inappropriate discharge re-mains a challenge that can lead to morbidity and death. We think that more research and development should focus on updating devices so that they filter common EMI sources and still detect myocardial signals associ-ated with dysrhythmias. Meanwhile, clinicians should advise patients to avoid potential hazards, including swimming pools that might contain leaking alternat-ing current. In addition, pool manufacturers should be advised of this risk to ICD and PPM patients and be urged to minimize electrical leaks.References  1. Buxton AE, Lee KL, Fisher JD, Josephson ME, Prystowsky EN, Hafley G. A randomized study of the prevention of sud-den death in patients with coronary artery disease. Multi-center Unsustained Tachycardia Trial Investigators [published erratum appears in N Engl J Med 2000;342(17):1300]. N Engl J Med 1999;341(25):1882-90.  2. Moss AJ, Zareba W, Hall WJ, Klein H, Wilber DJ, Cannom DS, et al. Prophylactic implantation of a defibrillator in pa-tients with myocardial infarction and reduced ejection frac-tion. N Engl J Med 2002;346(12):877-83.  3. Kadish A, Dyer A, Daubert JP, Quigg R, Estes NA, Anderson KP, et al. Prophylactic defibrillator implantation in patients with nonischemic dilated cardiomyopathy. N Engl J Med 2004;350(21):2151-8.  4. Powell BD, Asirvatham SJ, Perschbacher DL, Jones PW, Cha YM, Cesario DA, et al. Noise, artifact, and oversensing re-lated inappropriate ICD shock evaluation: ALTITUDE noise study. Pacing Clin Electrophysiol 2012;35(7):863-9.  5. Daubert JP, Zareba W, Cannom DS, McNitt S, Rosero SZ, Wang P, et al. Inappropriate implantable cardioverter-defibril-lator shocks in MADIT II: frequency, mechanisms, predic-tors, and survival impact. J Am Coll Cardiol 2008;51(14): 1357-65.  6. Lee SW, Moak JP, Lewis B. Inadvertent detection of 60-Hz alternating current by an implantable cardioverter defibrilla-tor. Pacing Clin Electrophysiol 2002;25(4 Pt 1):518-9.  7. Cohan L, Kusumoto FM, Goldschlager NF. Environmental effects on cardiac pacing systems. In: Kusumoto FM, Gold-schlager NF, editors. Cardiac pacing for the clinician. New York: Springer Science+Media, LLC; 2008. p. 595-618.  8. Astridge PS, Kaye GC, Whitworth S, Kelly P, Camm AJ, Per-rins EJ. The response of implanted dual chamber pacemakers to 50 Hz extraneous electrical interference. Pacing Clin Elec-trophysiol 1993;16(10):1966-74.  9. Garg A, Wadhwa M, Brown K, Luckett C, Vaughn T, Birgersdotter-Green U, Feld G. Inappropriate implantable cardioverter defibrillator discharge from sensing of external alternating current leak. J Interv Card Electrophysiol 2002;7 (2):181-4.10. Chan NY, Wai-Ling Ho L. Inappropriate implantable cardio-verter-defibrillator shock due to external alternating current leak: report of two cases. Europace 2005;7(2):193-6.11. Stevenson WG, Soejima K. Recording techniques for clinical electrophysiology. J Cardiovasc Electrophysiol 2005;16(9): 1017-22.12. Warnowicz-Papp MA. The pacemaker patient and the elec-tromagnetic environment. Clin Prog Pacing Electrophysiol 1983;1(2):166-76.13. Verga TA, Gillberg JM, Greenberg RM, Deger FT. True bipolar and integrated bipolar sensing and detection by im-plantable defibrillators. Pacing Clin Electrophysiol 2011;34 (11):1561-8.

Inappropriate Implantable Cardioverter-Defibrillator Shocks Attributed to Alternating-Current Leak in a Swimming Pool

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Inappropriate Implantable Cardioverter-Defibrillator Shocks Attributed to Alternating-Current Leak in a Swimming Pool

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