There are many types of heart monitors, but I was given a Zio XT ambulatory cardiac monitor to wear for seven days. This monitor is simply a data logger and has no means to transmit data or alert anyone if an anomaly is found. 

However, the device has a button that can be pressed if the person wearing the monitor experiences an unusual feeling or pain in the heart. A log book is provided so that the person reporting the condition can “bookmark” when the event occurred, and can write down what physical activity was occurring in the time that led up to the event.