Abstract: A monitoring system uses infrared photoplethysmography to monitor the pulse of a person wearing a wrist unit, and the wrist unit sends RF signals which describe his heart condition to a base unit. If the wrist unit detects a cardiac arrest or if the wearer manually signals an emergency, both the wrist and the base units sound local alarms. The base unit also telephones others outside of the user's home to alert them to the emergency. The wrist unit is designed to be fail-safe and to prevent false alarms. When the wrist unit fails to detect a pulse, it makes several further attempts to detect a pulse before signalling a cardiac arrest emergency. A prioritization and output activation circuit activates wrist unit outputs, including audio signals, an RF signal transmitter, and a display, according to a predetermined priority when more than one condition requiring a response exists.