Cardiac stimulation with electronic control device application.

BACKGROUND: Electronic control devices (ECDs) are weapons used to incapacitate violent subjects. Subjects have died suddenly after ECD application, but because cardiac dysrhythmias have been inconsistently observed during ECD application in animals, the cause for death is uncertain. OBJECTIVES: The objective was to identify the factors contributing to cardiac stimulation during ECD application detected by transesophageal echocardiography. METHODS: Four Yorkshire pigs were anesthetized, paralyzed with vecuronium, and restrained in a supine position. A GE 6T echo probe was placed in the esophagus to directly visualize left ventricular function. M-mode echocardiography was used to estimate heart rate. Two dart locations, chest and abdomen, were assessed. ECD applications were delivered from one of five commercially available devices (Taser X26, Singer S200 AT, Taser M26, Taser X3, and Taser C2) in random order to each pig, four times in each orientation. RESULTS: Cardiac stimulation, characterized by multiple PVCs or the sudden increase in ventricular contraction rate during application, did not occur with abdominal dart location. With chest dart application in small pigs, cardiac stimulation occurred with all ECDs except with the Taser X3 (p < 0.0001). In large pigs, cardiac stimulation occurred only during chest application of the S200 AT (chest vs. abdomen: 207 beats/min, vs. 91 beats/min, p < 0.0001). CONCLUSION: Cardiac stimulation occurs during ECD application in pigs, and is dependent upon subject size, dart orientation, and ECD. The Taser X3 did not result in cardiac stimulation in small or large pigs.

Cardiac safety of conducted electrical devices in pigs and their effect on pacemaker function.

OBJECTIVE: The aims of this study are to evaluate the cardiac safety of the Stinger S-200 Conducted Energy Weapon Device (CED) (Stinger Systems, Tampa, Fla) on a human-sized pig model and to test the effect of various commercially available CEDs, specifically the Stinger S-200, TASER M26 (Taser International, Scottsdale, Ariz), and TASER X26 on pacemaker function. METHODS: Two groups of pigs, divided based on weight as group 1 (n = 3, 67.3 ± 4.7 kg) and group 2 (n = 3, 89.3 ± 1.2 kg), were used. In protocol 1, the Stinger S-200 was applied in multiple different orientations to simulate possible field scenarios across the heart. In protocol 2, a single-chamber bipolar lead connected to a pacemaker was placed in the right ventricle of the pig, and different CEDs were applied to test the pacemaker function during CED application. RESULTS: In protocol 1, the S-200 was applied a total of 216 times in the 6 pigs, and neither episodes of ventricular fibrillation nor episodes of sustained ventricular tachycardia were noted. In protocol 2, the CED discharges (1) were recognized by the pulse generator and sensed as either high-rate atrial or ventricular activity, (2) did not affect the native rhythm, (3) did not conduct down the lead systems to cause any extra systoles, and (4) had no effect on paced rhythm. CONCLUSIONS: In this model, the application of the S-200 in various orientations across the heart did not result in any sustained abnormal cardiac rhythms. None of the tested CEDs adversely affected the functioning of the tested pacemaker. Stinger Systems has now replaced the S-200 with the S-200T with a different output.

Electrical parameters of projectile stun guns.

Projectile stun guns have been developed as less-lethal devices that law enforcement officers can use to control potentially violent subjects, as an alternative to using firearms. These devices apply high voltage, low amperage, pulsatile electric shocks to the subject, which causes involuntary skeletal muscle contraction and renders the subject unable to further resist. In field use of these devices, the electric shock is often applied to the thorax, which raises the issue of cardiac safety of these devices. An important determinant of the cardiac safety of these devices is their electrical output. Here the outputs of three commercially available projectile stun guns were evaluated with a resistive load and in a human-sized animal model (a 72 kg pig).

Cardiac safety of the surface application of the stinger s200.

Electronic Control Devices (ECDs) have been developed as less-lethal devices that law enforcement officers can use to control potentially violent subjects, as an alternative to using firearms. These devices apply high voltage, low amperage, pulsatile shocks to the subject, which causes involuntary skeletal muscle contraction and renders the subject unable to further resist. In field use of these devices, the electric shock is often applied to the thorax, which raises the issue of the cardiac safety of these devices. The present study evaluates the cardiac safety of the application of one such device to the torso of experimental animals.

Cardiac current density distribution by electrical pulses from TASER devices.

TASERs deliver electrical pulses that can temporarily incapacitate subjects. The goal of this paper is to analyze the distribution of TASER currents in the heart and understand their chances of triggering cardiac arrhythmias. The models analyzed herein describe strength-duration thresholds for myocyte excitation and ventricular fibrillation induction. Finite element modeling is used to compute current density in the heart for worst-case TASER electrode placement. The model predicts a maximum TASER current density of 0.27 mA/cm(2) in the heart. It is conclude that the numerically simulated TASER current density in the heart is about half the threshold for myocytes excitation and more than 500 times lower than the threshold required for inducing ventricular fibrillation. Showing a substantial cardiac safety margin, TASER devices do not generate currents in the heart that are high enough to excite myocytes or trigger VF.

Cardiac safety of neuromuscular incapacitating defensive devices.

Neuromuscular incapacitation (NMI) devices discharge a pulsed dose of electrical energy to cause muscle contraction and pain. Field data suggest electrical NMI devices present an extremely low risk of injury. One risk of delivering electricity to a human is the induction of ventricular fibrillation (VF). We hypothesized that inducing VF would require a significantly greater NMI discharge than a discharge output by fielded devices. The cardiac safety of NMI discharges was studied in nine pigs weighing 60 +/- 28 kg. The minimum fibrillating level was defined as the lowest discharge that induced VF at least once, the maximum safe level was defined as the highest discharge which could be applied five times without VF induction, and the VF threshold was defined as their average. A safety index was defined as the ratio of the VF threshold to the standard discharge level output by fielded NMI devices. A VF induction protocol was applied to each pig to estimate the VF threshold and safety index. The safety index for stored charge ranged from 15X to 42X as weight increased from 30 to 117 kg (P < 0.001). Discharge levels above standard discharge and weight were independently significant for predicting VF inducibility. The safety index for an NMI discharge was significantly and positively associated with weight. Discharge levels for standard electrical NMI devices have an extremely low probability of inducing VF.

Transthoracic defibrillation of dogs with Edmark, biphasic, and quadriphasic waveforms.

Patients with high transthoracic impedance are reported to be at higher risk of poor outcomes when treated by present defibrillators. This study evaluates the defibrillation efficacy of biphasic truncated exponential (BTE), quadriphasic truncated exponential (QTE), and Edmark waveforms at simulated low, average, and high impedance levels. Waveforms were tested at 2 energy levels in random order in anesthetized dogs (n = 15, 16.9 +/- 1.2 kg), and a supplemental study estimated the ED50 peak current for BTE and QTE at a simulated high impedance level. Overall, BTE and QTE were equivalent, and both were superior to Edmark at equal delivered energies (P<.0001). However, in simulated high impedance patients at 24 J, QTE was superior to BTE (71% vs. 49%, P =.011 (borderline significance-see text)). Supplemental study, QTE mean ED50 peak current was lower than BTE (7.9 vs. 8.9 A, P =.0049). QTE and BTE waveforms were superior to Edmark at all studied conditions, but QTE appears to be superior to BTE in simulated high impedance patients.