In medicine, a<unk>  (often simply<unk>  is a type of ambulatory electrocardiography device, a portable device for cardiac monitoring (the monitoring of the electrical activity of the cardiovascular system) for at least 24 to 72 hours (often for two weeks at a time). The<unk> 's most common use is for monitoring ECG heart activity (electrocardiography or ECG). Its extended recording period is sometimes useful for observing occasional cardiac arrhythmias which would be difficult to identify in a shorter period. For patients having more transient symptoms, a cardiac event monitor which can be worn for a month or more can be used. The<unk>  was developed at the<unk>  Research Laboratory in Helena Montana by experimental physicists Norman J.<unk>  and Bill Glasscock, who started work on radio telemetry in 1949. Inspired by a suggestion from cardiologist Paul Dudley White in the early 1950s, they redirected their efforts toward development of a wearable cardiac monitoring device. The<unk>  was released for commercial production in 1962. When used to study the heart, much like standard electrocardiography, the<unk>  records electrical signals from the heart via a series of electrodes attached to the chest. Electrodes are placed over bones to minimize artifacts from muscular activity. The number and position of electrodes varies by model, but most<unk> s employ between three and eight. These electrodes are connected to a small piece of equipment that is attached to the patient's belt or hung around the neck, keeping a log of the heart's electrical activity throughout the recording period. A 12-lead<unk>  system is also available when precise ECG’s information is required to analyse the exact origin of the abnormal signals.
Holter monitor
Heart rate monitor
Vectorcardiography
Cardiotocography
Electrical cardiometry
Electrocardiography
Impedance cardiography
Sphygmograph