Tasering could affect heartbeat, Toronto researchers find

May 1, 2008
Sharon Kirkey, Canwest News Service

Despite the theory that stun guns don't harm internal organs such as the heart, Canadian researchers are reporting that, in fact, research suggests stun gun discharges are able to stimulate heart muscle under certain circumstances.

"In our view it is inappropriate to conclude that stun gun discharges cannot lead to adverse cardiac consequences in all real-world settings," Dr. Kumaraswamy Nanthakumar, of the University of Toronto, and colleagues report in the Canadian Medical Association Journal, published online Thursday.

The researchers studied a total of 150 discharges in six anesthetized pigs and found that 74 of the discharges resulted in stimulation of the myocardium, or heart muscle.

"We took care to ensure that the gun barbs did not pierce deep into the tissue," the researchers reported, just days before a B.C. inquiry into the death of Polish immigrant Robert Dziekanski is set to begin. Dziekanski was Tasered by the RCMP last October after he began behaving erratically in a secure area of Vancouver airport, and died shortly after.

The researchers from the University of Toronto and two Toronto hospitals found that the positioning of the barbs, which transmit the electrical impulses from the device, played a key role. Placing them across the chest, nearest the heart, simulated "the worst-case scenario of creating a current vector that directly passes through the heart," the researchers reported.

If the barbs were placed away from the chest and across the abdomen, none of the 56 test discharges stimulated the heart, "suggesting that the location of the barbs had a crucial influence on stimulating the heart."

In one study, the pigs' blood pressure was suddenly lost after a stun gun, such as a Taser, was discharged. In another study, two animals died from ventricular fibrillation - rapid, uncontrolled contraction of the heart - immediately after being Tasered.

"This suggests that sufficient current density was produced by the stun gun to stimulate the heart, which, according to theory, should not and could not occur."

"Three different studies involving pigs, one of which was performed by us, have shown that a stun gun discharge can stimulate the heart,"Nanthakumar noted.

The team cautions that a human's chest is different from that of a pig, and that "one should be prudent in extrapolating data from animals to humans because of this fact." Still, most of what's known about cardiac defibrillation comes from studies in animals, not humans.

In an accompanying editorial, CMAJ deputy editor Dr. Matthew Stanbrook says deaths occurring in association with Tasers "make the safety of these devices a public health issue."

He says police should share information about their use, and that information that should be analyzed by independent researchers, "on the principle that the assertion that Tasers have saved lives of police and suspects alike, while plausible, should be proven, not merely asserted as fact."

"New and independent research, both epidemiologic and biological, into whether Tasers can kill is essential to settle this issue."

More than 300 deaths following stun gun use have been documented, 20 of them in Canada.
The devices are used to physically incapacitate a person by discharging controlled electric energy into the body.

The Toronto researchers found no conclusive evidence to show whether stun guns can cause erratic heartbeats sometime later, after the stun gun discharge is complete.