doi: 10.1161/CIRCULATIONAHA.107.692129
(Circulation. 2007;115:e472-e474.)
© 2007 American Heart Association, Inc.
Images in Cardiovascular Medicine |
Duration of Discharge of Neuromuscular Incapacitating Device and Inappropriate Implantable Cardioverter-Defibrillator Detections
From the University of Toronto, Toronto, Canada.
Correspondence to Kumaraswamy Nanthakumar MD, Division of Cardiology, University Health Network, Toronto General Hospital, 150 Gerrard St West, PMCC 3–522, Toronto ON M5G 2C4, Canada. E-mail nanthaj{at}yahoo.com
Neuromuscular-incapacitating devices (NID) are being used increasingly worldwide by law-enforcement authorities to restrain violent behavior.1 Electrical noise-related, inappropriate detection by implantable cardioverter-defibrillator (ICD) has been documented.2,3 Detection of NID discharge by ICD has been described,4,5 but the effects of duration of NID discharge and ICD detection and therapy have not been established. The authors hypothesized that a longer duration of NID energy might lead to shocks from the defibrillator.4
With the approval of the animal care committee of our institution, we tested this hypothesis in a pig implanted with Medtronic 7275 GEM III DR ICD. The method used for performing the experiment in a pig model has been described previously.6 In the present study, we used subcutaneous insertion of the darts. Particular attention was given to ensure that the darts were in the subcutaneous tissue and not any deeper, to avoid any possibility of direct stimulation through the pericardium. Two darts were placed: one in the right parasternal region, 5 cm from the midline; and another at the left lateral border of the thorax. The interdart distance was 30 cm. The NID energy was delivered for 5 and 15 s across the chest, using the M26 TASER (TASER International, Scottsdale, Ariz). When the NID discharge was delivered for 5 s, the device detected NID energy as ventricular fibrillation (VF), but no ICD shock was delivered; during charging of the capacitors, the device reconfirmed that the episode had terminated (Figure 1). However, when the NID energy was delivered for a longer time (15 s), the device detected NID energy as VF, and a shock was delivered (Figure 2A). As the NID energy continued, the device redetected this as VF, and even though the NID delivery had stopped during capacitor charging, a second ICD shock was delivered because the device was in committed mode during the second therapy for VF (Figure 2B).
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The implications of the present study are that (1) in patients with more recent devices, longer (15 s) NID energy delivery could result in ICD discharge; (2) because most devices are committed to deliver a shock after the first VF therapy, inappropriate shock may be delivered during sinus rhythm, even after NID energy is no longer being delivered; and (3) with older ICD models that only have committed shock delivery, even a short burst of NID energy delivery could result in inappropriate ICD discharges.
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1. Kornblum RN, Reddy SK. Effects of the Taser in fatalities involving police confrontation. J Forensic Sci. 1991; 36: 434–448.[Medline] [Order article via Infotrieve]
2. Kolb C, Zrenner B, Schmitt C. Incidence of electromagnetic interference in implantable cardioverter defibrillators. Pacing Clin Electrophysiol. 2001; 24: 465–468.[CrossRef][Medline] [Order article via Infotrieve]
3. Sweesy MW, Holland JL, Smith KW. Electromagnetic interference in cardiac rhythm management devices. AACN Clin Issues. 2004; 15: 391–403.[Medline] [Order article via Infotrieve]
4. Haegeli LM, Sterns LD, Adam DC, Leather RA. Effect of a Taser shot to the chest of a patient with an implantable defibrillator. Heart Rhythm. 2006; 3: 339–341.[CrossRef][Medline] [Order article via Infotrieve]
5. Marine JE. Stun guns: a new source of electromagnetic interference for implanted cardiac devices. Heart Rhythm. 2006; 3: 342–344.[CrossRef][Medline] [Order article via Infotrieve]
6. Nanthakumar K, Billingsley IM, Masse S, Dorian P, Cameron D, Chauhan V, Downar E, Sevaptsidis E. Cardiac electrophysiological consequences of neuromuscular incapacitating device discharges. J Am Coll Cardiol. 2006; 48: 798–804.
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