Add Yahoo as a preferred source to see more of our stories on Google. As people follow Nancy Guthrie's disappearance, people are wondering how investigators are using her pacemaker to find her.

Q: My mom is 93, and her doctor says she needs a pacemaker to control a heart arrhythmia. How does a pacemaker work? Is the operation dangerous for someone her age?

CHICAGO — One person’s used pacemaker is another person’s treasure. A program to refurbish used pacemakers could expand access to the lifesaving devices. In a clinical trial of nearly 300 people, ...