In an article published by the American Heart Association, a study of eight cases of people who lost consciousness immediately after being shocked by a TASER X26--the most common electronic control device (ECD) used by police, prisons and the military--concluded that ECD shocks can induce fatal cardiac arrest by capturing the heat rhythm and causing ventricular tachycardia/ventricular fibrillation (VT/VF). Seven of the eight died and the eighth suffered memory impairment after receiving the near-fatal shock.

The eight subjects of the study were all male and ranged from 16 to 44 years of age. Six were under the age of 25. All were struck in the chest with 9 or 13-mm barbs from a TASER X26, a handgun-shaped weapon which fires the barbs and attached conductive wires using compressed nitrogen, then delivers an initial 50,000-volt shock followed by 100-microsecond pulses at around 19 times per second consisting of a 2 to 4 amp, approximately 1200-volt, 100-microsecond discharge per pulse. The standard shock cycle lasts 5 seconds, but can be repeated, shortened or lengthened by the user.

The study noted that the safety of ECDs had been questioned and that Amnesty International had documented 334 post-ECD-shock deaths occurring between 2001 and 2008. A report from a commission of inquiry into the death of a man at the Vancouver, 8.C. airport concluded that there was evidence "that the electric current from a conducted energy weapon is capable of triggering ventricular capture...and that the risk of ventricular fibrillation increases as the tips of the probes get closer to the walls of the heart," but no peer-reviewed publication had heretofore concluded that ECD shocks can induce ventricular fibrillation leading to sudden cardiac arrest and death.

All the eight subjects were clinically healthy. All received one or both barbs in the anterior chest wall near the heart. All lost consciousness during or immediately following ECD discharge. In six cases, the first recorded rhythms were VT/VF. One had no heart rhythm and in one an external defibrillator reported a shockable rhythm but did not record it.

Two of the subjects had structural heart disease, two had elevated blood alcohol concentrations and two had both. However, these were considered unlikely to be the cause of the sudden loss of consciousness which occurred at the time or immediately after they received the TASER shocks, although it might have increased the likelihood of ECD-induced VT/VP. The study also concluded that it was unlikely that other known causes of in-custody death, such as "excited delirium" or restraint asphyxia, were factors in the deaths due to the proximity of the electroshock to the loss of consciousness.

The article noted that studies in pigs, sheep and humans established that shocks across the chest from the TASAER X26 and a new prototype ECD could cause cardiac capture. The pig studies also repeatedly showed that the TASER X26 could induce VT/VF at normal or higher-than-normal outputs. Similar studies attempting to induce VT/VF by placing the barbs in the anterior chest and using strong, multiple and/or lengthy exposures could not be conducted on humans due to ethical considerations. However, studies from years ago showed that runaway pacemakers could induce VT/VF.

The article noted that sudden death occurred infrequently after ECD use. However, it urged ECD users to consider the fact that ECD deployment was not risk-free and to avoid placing electrodes in the chest or administering lengthy or repeated shocks and to be prepared to resuscitate, including the use of an automated external defibrillator.

Source: Sudden Cardiac Arrest and Death Associated With Application of Shocks From a TASER Electronic Control Device, Douglas P. Zippes, M.D, www.ahajournals.org

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