Go into cardiac arrest and your chances of survival plummet every minute you don't get help. CPR-trained citizens can save lives, but how would they know if there's an emergency? Now, there's an app for that. The city of Chesapeake on Wednesday launched a free mobile app called PulsePoint, which notifies CPR-trained users of sudden cardiac arrests in nearby public places. The idea is to get people the help before first responders arrive.