Impedance cardiography (ICG) is a noninvasive technique for assessing cardiovascular function by measuring variations in thoracic bioelectrical impedance associated with cardiac activity.
Changes in blood volume during the cardiac cycle leads to corresponding impedance variations, from which the impedance cardiogram and its first derivative (dZ/dt) can be derived.
From dZ/dt, specific waveform points (A, B, C, X, O) are identified. Using these points, key hemodynamic parameters such as:
- Stroke Volume (SV)
- Left Ventricular Ejection Time (LVET)
can be calculated continuously and noninvasively.
Due to its noninvasive nature, simplicity, and capability for continuous monitoring, ICG has been widely applied in vital signs monitoring (VSM) and cardiovascular assessment.