Dr Amin Karami told a meeting of the American Heart Association that pacemaker batteries needed to be replaced approximately every seven years.

BBC: Heartbeat 'could power pacemaker'

ATLANTA, Georgia (CNN) -- A pacemaker device could help up to half of all heart failure patients live a more active life, researchers told the American College of Cardiology Tuesday.

CNN: Pacemakers found to help heart failure patients

Their team showed that the device could generate 18 times the amount of energy needed to power a pacemaker using a normal heart beat, according to Dr. Karami.

WSJ: Harnessing Energy From the Body to Power Devices