Observational Study of Human Electrical Muscle Incapacitation and Cardiac Effects

Abstract : Human Electrical Muscular Incapacitation (HEMI) is used to subdue combative individuals. Changes in cardiac electrical activity have been proposed as the cause of death in a small fraction of these individuals. A study of 212 patient exposures to 1000 volts found 28 (14 ) developed QT prolongation. The current study sought to determine if changes in QTc interval occur after HEMI exposure. Twenty-four participants had EKG readings before a 5-second HEMI exposure and within 30 minutes after exposure. All subject EKGs were read by a data-blinded cardiac electrophysiologist who calculated a QT corrected (QTc) interval. QTc interval was calculated using Bazett, Fridericia, and Framingham methods. QTc prolongation was defined as 430 ms and a threshold of 30 ms for identifying QTc lengthening. Using the Bazett method, five participants experienced QTc prolongation and six had QTc lengthening. One participant developed QTc prolongation exceeding 500 ms, which carries a risk of developing multifocal ventricular tachycardia. These results suggest that HEMI exposure may cause EKG changes with a risk of ventricular tachycardia.