Impedance Cardiography (ICG)
Impedance cardiography (ICG), also known as thoracic electrical bioimpedance (TEB), is a noninvasive diagnostic procedure that measures the volume of blood flow in the thorax. This diagnostic test obtains information about a patient's hemodynamic status, and provides information about conditions such as congestive heart failure, hypertension and the pacemaker maintenance. This technology was originally used by NASA in the 1960s to better understand the cardiac cycle of astronauts when in space.
The ICG technology evaluates changes in thoracic impedance to changes in volume over time. The ICG procedure is performed by placing four sensors on the neck and chest to transmit and detect electrical charges in the thorax in order to measure the resistance in the chest and determine the force that the heart has to pump against in order to deliver blood to the rest of the body.