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Biomedical Functional Imaging and Neuroengineering Laboratory

College of Science & Engineering > Dept. of Biomedical Engineering

Cardiac Electrical Imaging

It is of significance to noninvasively image cardiac electrical activity throughout the three dimensional (3D) myocardium. We have developed novel 3D cardiac electrical tomography techniques to image cardiac current density distributions within the myocardium (He & Wu, IEEE-TITB, 2001, pdf), and a heart-model based tomographic imaging approach to localize the site of origin of cardiac activation (Li & He, 2001, IEEE-TBME, pdf); Li et al., IEEE-TBME, 2003, pdf), image cardiac activation sequence (He et al., Physics Med. & Biol., 2002, Abstract), and image the transmembrane potential distribution (He et al., IEEE-TBME, 2003, pdf) within the 3D anisotropic myocardium in a realistic geometry inhomogeneous heart-torso model. The feasibility of our 3D imaging approach to estimate 3D activation sequence has been rigorously validated in a rabbit model using 3D intracardiac mapping (Zhang et al., Am. J. Physiology, 2005, Full Text). We have also developed a novel ECG inverse approach for imaging the 3D ventricular activation sequence, which is based on the estimation of the equivalent current density throughout the entire volume of ventricular myocardium (Liu et al, IEEE-TMI, 2006, pdf), and validated initially this approach in rabbits (Han et al., IEEE-TMI, 2008, pdf). The spatio-temporal coherence of ventricular excitation process has been utilized to derive the activation time from the estimated time course of equivalent current density defined as the spatial gradient of transmembrane potential. In addition, we have proposed a novel approach to cardiac electrical tomography using intracavitary recordings (He et al., IEEE-TBME, 2007, pdf). This minimally invasive approach enables imaging and ablation in a single session. These works are highly promising and may lead to establishment of 3D cardiac electrical tomography technology for functional cardiac imaging, aiding catheter ablation of arrhythmias and other cardiac applications.

Fig. 1 Schematic diagram of 3D electrocardiographic activation imaging.

Fig. 2 Schematic diagram of the experimental protocol. Simultaneous 3-D intracardiac mapping and body surface potential mapping were conducted and the measured activation sequence from 3-D intracardiac mapping is compared with the imaged activation sequence obtained by the 3-D cardiac activation imaging technique. (from Han et al., IEEE Trans. Medical Imaging, 2008)