An electrocardiograph is commonly referred to as an ECG or EKG, which stands for electrocardiogram. It is a device that measures the electrical activity of the heart and produces a graphical representation of this activity. Other synonyms for electrocardiograph include cardiac monitor, heart monitor, and heart rate monitor. These devices are used in hospitals and medical facilities to monitor and diagnose various heart conditions such as arrhythmias, ischemia, and infarctions. Other related terms include Holter monitor and event monitor, which are devices used to monitor the heart's electrical activity over a longer period of time, usually 24 hours or more.