The impedance cardiography technique in medical diagnosis

Abstract

Background: Thoracic Electrical Bioimpedance (TEB) Technology sometimes called the Impedance Cardiography (ICG). In 1940, the Impedance Cardiography emerged; the studies of this technique are realized to the cardiovascular diseases detection which used hemodynamic parameters measurements based on the skin electrodes contact by injecting a low amplitude alternating signal. The objective of this article is to review the various studies based on this signal type and to present the multiple methods used for the treatment and to have a correct analysis.
 Methods: This ICG technique consists for applying an electric field longitudinally across a segment of the thorax with amplitude in mean, high frequency and low amplitude current. To analyze the ICG signal, the signal denoising is necessary that’s why a multiple filters are proposed, and the Discrete Wavelet Transform (DWT) denoising is also used.
 Results: The ICG is considered advantageous compared to other invasive conventional techniques; it gives a good correlation, and solves the Doppler ultrasound and Thermodilution problems. According to the studies, the Daubechies wavelet family (db8) is the best DWT to eliminate the noises. There are several algorithms for the signal characteristic point’s detection.
 Conclusion: For the purpose of cardiovascular disease diagnosis and monitoring, the non-invasive ICG technique comes to solve the complexity problem for measurement and analyzing heart disease based on the thoracic electrical impedance change assessment that is due to blood velocity and resistivity changes (blood volume changes) in order to estimate several hemodynamic parameters.
 Keywords: ICG, cardiovascular disease, hemodynamic parameters, diagnosis and monitoring, correct analysis.

Cardiovascular diseases diagnosis by impedance cardiography

“…The ICG measurements can be affected by the biological composition, respiration, noise due to movement or equipment, blood circulation, volume blood from the transthoracic region, electrodes configuration and types [ 6 ]. The papers and studies presented in the previous section each focus on a given CVD and not on all CVDs.…”

“…It allows obtaining continuous and real-time hemodynamic data measurements as well as the diagnosis of several cardiovascular diseases, in particular by using the impedance cardiography (ICG) technique. It also provides a better distribution where the noises are minimal, and the electrode-skin surface impedance is low [ 6 ].…”