ORLANDO, Fla., Nov. 6 (UPI) -- More than 500 lives could be saved annually in the United States and Canada if automated external defibrillators were widely placed in public spaces.

The paddle-fitted, battery-powered devices, known as AEDs, are used to shock and revive people whose hearts have suddenly stopped beating before paramedics can reach them at senior care facilities, hospitals, sports stadiums, community centers, shopping malls, airports and the lobbies of large hotels and office buildings.

Principal investigator Dr. Myron "Mike" L. Weisfeldt, a cardiologist at The Johns Hopkins University School of Medicine in Baltimore, said more than 300,000 Americans of all ages die from sudden cardiac death annually.

"Our results were emphatically clear, Good Samaritans, when given access to automated defibrillators in potentially fatal emergencies, save lives," Weisfeldt said in a statement. "This is a serious matter of public health policy and similar to previous discussions about placing fire extinguishers near building exits, wearing seat belts while driving, or manufacturing cars with airbags."

The devices costs about $2,000 and are equipped with a digital instruction screen that provides simple, step-by-step directions that a bystander can apply.

The findings were presented at the American Heart Association’s annual scientific sessions in Orlando, Fla.