Abstract 17255: Noninvasive Three-dimensional Cardiac Activation Imaging of Ventricular Tachycardia in the Rabbit Heart
Introduction: Imaging myocardial activation is of importance for cardiovascular research and clinical medicine. The present study aims to assess the performance of 3-dimensional cardiac electric imaging (3-DCEI) for intramural imaging of cardiac arrhythmia from noninvasive body surface potentials, as validated by simultaneous intracardiac mapping from up to 216 intramural sites during VT in the rabbit heart.
Methods: Body surface potentials were obtained simultaneously with intramural bipolar recordings from plunge-needle electrodes in a closed-chest condition in six healthy rabbits. Nonsustained monomorphic VTs (MVTs) (n=4) and premature ventricular complexes (PVCs) (n=7) induced by i.v. norepinephrine (NE) were analyzed in four rabbits. Nonsustained polymorphic VTs (PVTs) (n=4) and PVCs (n=8) induced during i.v. infusion of phenylephrine and clofilium were analyzed in another two rabbits. CT images were obtained after the mapping study for constructing realistic geometry model for each animal.
Results: Good correlation was obtained between non-invasively imaged activation sequence and measured activation sequence from 3-dimensional (3-D) intramural mapping with a correlation coefficient of 0.70±0.06, and a relative error of 0.31±0.04 averaged over 115 ectopic beats. The NE induced MVTs initiated by a focal (nonreentrant) mechanism as revealed by 3-DCEI and confirmed by direct intracardiac mapping. For the phenylephrine and clofilium induced PVTs, different focal initiation sites were observed in a single run. PVTs exhibited torsade de pointes (TdP) form with twisted QRS complexes around the isoelectric axis in ECG leads. Sites of initial activation were localized to be ∼5mm for the ectopic beats.
Conclusions: The 3-DCEI technique can non-invasively image the 3-D activation sequence of focal VT. It offers the potential to aid catheter ablation and to non-invasively assess the mechanisms of ventricular arrhythmias on a beat-to-beat basis.
- © 2010 by American Heart Association, Inc.