Cardiac monitoring generally refers to continuous or intermittent monitoring of heart activity, generally by electrocardiography, with assessment of the patient’s condition relative to their cardiac rhythm. It is different from hemodynamic monitoring, which monitors the pressure and flow of blood within the cardiovascular system. The two may be performed simultaneously on critical heart patients. Cardiac monitoring with a small device worn by an ambulatory patient (one well enough to walk around) is known as ambulatory electrocardiography (such as with a Holter monitor, wireless ambulatory ECG, or an implantable loop recorder). Transmitting data from a monitor to a distant monitoring station is known as telemetry or biotelemetry.