Noninvasive imaging of three-dimensional cardiac activation sequence during pacing and ventricular tachycardia

Abstract

Background Imaging cardiac excitation within ventricular myocardium is important in the treatment of cardiac arrhythmias and might help improve our understanding of arrhythmia mechanisms. Objective This study aims to rigorously assess the imaging performance of a three-dimensional (3-D) cardiac electrical imaging (3-DCEI) technique with the aid of 3-D intra-cardiac mapping from up to 216 intramural sites during paced rhythm and norepinephrine (NE) induced ventricular tachycardia (VT) in the rabbit heart. Methods Body surface potentials and intramural bipolar electrical recordings were simultaneously measured in a closed-chest condition in thirteen healthy rabbits. Single-site pacing and dual-site pacing were performed from ventricular walls and septum. VTs and premature ventricular complexes (PVCs) were induced by intravenous NE. Computer tomography images were obtained to construct geometry model. Results The non-invasively imaged activation sequence correlated well with invasively measured counterparts, with a correlation coefficient of 0.72±0.04, and a relative error of 0.30±0.02 averaged over 520 paced beats as well as 73 NE-induced PVCs and VT beats. All PVCs and VT beats initiated in the subendocardium by a nonreentrant mechanism. The averaged distance from imaged site of initial activation to pacing site or site of arrhythmias determined from intra-cardiac mapping was ~5mm. For dual-site pacing, the double origins were identified when they were located at contralateral sides of ventricles or at the lateral wall and the apex. Conclusion 3-DCEI can non-invasively delineate important features of focal or multi-focal ventricular excitation. It offers the potential to aid in localizing the origins and imaging activation sequence of ventricular arrhythmias, and to provide noninvasive assessment of the underlying arrhythmia mechanisms.

Forward Problem of Electrocardiography

“…However, inverse solutions that use homogeneous models seem to be less accurate in vivo. [21][22][23][24] The need to incorporate inhomogeneities in inverse mapping techniques, which could be used in a clinical setting has been widely debated. On the one hand, it has been shown that inhomogeneous inverse solutions correspond more closely with epicardial potential maps in the absence of noise.…”

Noninvasive Imaging of High-Frequency Drivers and Reconstruction of Global Dominant Frequency Maps in Patients With Paroxysmal and Persistent Atrial Fibrillation

“…The CEI technique was previously used to reconstruct 3-D ventricular cardiac activation patterns from BSPM, and has been validated with animal studies [11–13, 24, 25]. In the present study, CEI was used to image atrial electrical activity.…”

“…Due to the very thin nature of atria over most areas, such approximation is deemed appropriate and supported by our promising clinical results. In a more accurate source model, one would need to account for the volume nature of atria by expanding the 2D atrial surface current density source model to a 3D atrial current density source model (see [7]–[13], e.g. ).…”

“…The LA and RA were discretized into 2282 ± 576 grid points with a spatial resolution of 3mm. The 2-D atrial ECD distributions were then reconstructed from the BSPM with the aid of the patient-specific heart-torso boundary element geometry model obtained from subjects’ CT images [11–13]. In order to image AF drivers exciting at relatively stable high frequency, a fixed 5-seconds length of BSPMs was used for analysis to ensure the capture of reliable high-frequency source.…”

A Brief History of Tissue Models For Cardiac Electrophysiology

“…Another promising approach for validating whole heart models is to use electrocardiographic imaging, which noninvasively images cardiac electrical activity in the heart [98]. Recently, He and colleagues demonstrated that a new 3-D cardiac electrical imaging method, which uses current sources, has the ability to noninvasively identify important features of ventricular excitation throughout the myocardium [99], [100]. These 3-D inverse techniques may prove critical in developing and tuning the next generation of patient specific models of the heart.…”