Original contribution
Cardiac Monitoring of Human Subjects Exposed to the Taser®

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Abstract

The Taser® (TASER International, Scottsdale, AZ) is a high-voltage, low-amperage device used by many law enforcement agencies. Our objective in this study was to evaluate for rhythm changes utilizing cardiac monitoring during deployment of the Taser® on volunteers. A prospective, observational study evaluated law enforcement personnel who had continuous electrocardiographic monitoring immediately before, during, and after having a voluntary exposure to the Taser X-26®. Changes in cardiac rate, rhythm, ectopy, morphology, and conduction intervals were measured. A total of 105 subjects were evaluated. The mean shock duration was 3.0 s (range 0.9–5 s). Mean heart rate increased 15 beats/min (95% CI 12.6–18.3), from 122 beats/min before shock to 137 beats/min immediately after shock. One subject had a single premature ventricular contraction both before and after the shock, but no other subject developed ectopy or dysrhythmia. Poor inter-rater agreement prevented determination of the overall effect of shock on conduction intervals. However, several interpretable tracings demonstrated change in QT duration—either shortening or prolongation after shock. Human subjects exposed to a brief shock from the Taser® developed significant increases in heart rate, but there were no cardiac dysrhythmias or morphologic changes. Alterations in the QT interval were observed in some subjects but their true incidence and clinical significance are unknown.

Introduction

Over the past decade there has been growing interest in less-lethal weapons to control violent and dangerous subjects without the use of firearms. The Taser® (short for Thomas A. Swift Electric Rifle, TASER® International, Scottsdale, AZ) is a handheld weapon that delivers high voltage, low amperage electricity causing forceful muscular contractions and incapacitation. This type of weapon is also known as a neuromuscular incapacitating device (NID) or conductive energy device (CED).

The electricity generated by the Taser® is neither a direct nor an alternating current, but actually a combination of both, consisting of a dampened, pulse sinusoidal wave. The output is 50,000 volts, with a maximal current of nearly 36 milliamps.

Although the weapon is generally regarded as safe, there have been injuries as well as sudden death reported in association with its use. Concerns have been raised over possible cardiac damage and induction of dangerous dysrhythmias, including ventricular fibrillation (1, 2). Prior studies using animal models have evaluated the cardiac effects of CEDs (3, 4, 5). The general conclusions reached from these studies are that the device operates at an electrical level below that of the threshold for ventricular fibrillation and is safe. Experience with CED use on humans includes reports of their safe deployment on more than 100,000 police volunteers (6).

We sought to evaluate the effect of a CED, the Taser X-26®, on the heart rhythm, rate, and electrocardiographic conduction intervals after deployment of a brief shock.

Section snippets

Study Design

This was a prospective, observational study of resting, adult law enforcement officers with the San Diego Police Department and the San Diego County Sheriff‘s Department. The subjects enrolled in our study were credentialed officers and not trainees. All subjects were already undergoing training with the Taser® X-26 and had the opportunity to volunteer to receive a CED activation as part of the training with the weapon. Only those subjects who had already volunteered to be exposed to the CED as

Results

A total of 115 subjects were enrolled into the study. Ten subjects’ data were excluded due to electrocardiographic leads becoming dislodged during the shock. Of the 105 remaining subjects, average shock duration was 3.0 s (range 0.9–5 s). No change in cardiac morphology was appreciated in any subject. No ectopy was appreciable except in one subject with an isolated premature ventricular contraction both before and after the CED activation.

The mean change in heart rate in the 105 subjects was an

Discussion

Conducted energy devices (CEDs) such as the Taser X-26® are being increasingly used as an alternative to lethal force. The devices are generally regarded as safe, especially when compared to conventional firearms (7). The weapons are neither analyzed nor licensed by the Food and Drug Administration, and human studies were not required for their approval. The device is considered a less-lethal weapon, rather than a firearm, under the Bureau of Alcohol, Tobacco and Firearms.

The CED used in our

Conclusions

In this study in human volunteers, a significant increase in heart rate was found after a brief shock from a CED, the Taser X-26®. There were no other identified cardiac rhythm disturbances or morphology changes except for a few subjects who appeared to have QT changes, the significance of which is unclear.

Acknowledgments

We thank the San Diego Police Department and the San Diego County Sheriff’s Department volunteers who participated in this study. Additionally, the authors thank the San Diego Fire-Rescue Department for providing the cardiac monitors used in the study.

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