On the eve of the British Columbia inquiry into the death of Robert Dziekanski, a review of scientific data in CMAJ (Canadian Medical Association Journal) finds that in some cases, stun guns may stimulate the heart in experimental models. This evidence is contrary to current views that stun guns only affect skeletal muscles.
"The frequency and the shape of the pulses generated by stun guns are designed to incapacitate the target by electrically overwhelming his or her control of these muscles," state Dr. K. Nanthakumar and colleagues. "In principle, these pulses are designed to act only on skeletal muscles and to not affect internal organs such as the heart." The evidence that stun guns do not stimulate the heart is based on "…theoretical studies [that] suggest that stun guns cannot deliver the amount of energy required to stimulate the heart or cause ventricular fibrillation."
Dr. Nanthakumar and collegues point out that most theoretical and some experimental studies reveal that cardiac stimulation does not occur with stun gun discharges. However, experimental studies on pigs by 3 independent groups of investigators found that "a stun gun discharge can stimulate the heart" depending on the location of the stun gun barbs. Barbs that are located such that they form a vector across the heart have greater effect than those focused on the abdomen. In one study, swine blood pressure was abruptly lost after discharge of a stun gun, and another study "reported the deaths of 2 animals caused by ventricular fibrillation immediately after the stun gun discharge….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."