Duration of Discharge of Neuromuscular Incapacitating Device and Inappropriate Implantable Cardioverter-Defibrillator Detections
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).
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.