According to the American Heart Association, approximately 166,200 out-of-hospital cardiac arrests occur each year. It is estimated that a victim's chances of survival are reduced by 7-10 percent for every minute that passes without treatment. Obviously, time is very critical in such situations. In most cardiac arrest cases, there is little to no warning to the victim that their heart has stopped and thus no time to notify others that emergency care is immediately required. To help alert the victim and others that a cardiac arrest episode has occurred, an ambulatory alarm and notification system has been built for individuals at high risk of cardiac arrest. The cardiac arrest alert system uses a ring-style photoplethysmograph that is connected to an armband unit which performs signal processing and wireless transmission and possesses an audible alarm. A wristband interface provides visual and tactile warnings, a reset button and a threshold adjuster. If the user's heart rate goes outside the preset range or is not detected by the system, a visual and tactile warning notifies the user of the situation. If the device is not reset or the problem not rectified within several seconds, the device then goes into full activation mode and sounds a loud alarm to notify nearby individuals who may be able to provide emergency assistance to the user. In full activation mode, the device also wirelessly transmits a signal to a central unit that, when signaled, automatically calls 911 and plays a pre-recorded message that states the incident and specifies the location. An additional phone number can also be stored so that another notification call is automatically performed. The central unit has a speaker so that the notification message is locally audible as well. In emergency situations, the cardiac arrest alert system will provide a life-saving service by rapidly alerting the user as well as nearby individuals and emergency respondents who can provide immediate assistance.