Scientists build a biological pacemaker by injecting a modified virus…

Our heartbeats are triggered by a steady stream of electrical signals, which cause our heart muscles to contract with a regular rhythm. For some people, however, the ‘pacemaker cells' responsible for generating these pulses can fail, resulting in an erratic heartbeat. Normally, this problem is addressed by surgery and … » 12/17/12 8:00am 12/17/12 8:00am