A Systematic Investigation of Intracardiac Inverse Mapping

Abstract

Atrial fibrillation (AF) is the most common heart rhythm disturbance and percutaneous catheter ablation is widely used to reverse paroxysmal AF. This approach has been much less successful for patients with persistent AF and real-time mapping of 3D electrical activity is needed to identify ablation targets in this complex arrhythmia. Balloon mounted or open multi-electrode basket catheters have been used for mapping of complex focal arrhythmias, but it is hard to achieve uniform contact between electrodes and the atrial endocardium. Inverse methods, in which endocardial surface potentials can be reconstructed from noncontact recordings, provide a better alternative. In this thesis, we have developed a novel inverse mapping approach which can be used with open multi-electrode basket catheters when some or all electrodes are not in contact with the atrial wall. Our systematic computational analysis demonstrates that 1) region-of-interest (ROI) mapping with noncontact open basket catheter can be used to reconstruct accurate local endocardial electrograms, and 2) reliable global mapping is feasible with potentials recorded by electrodes uniformly distributed within the cavity. In addition, an experimental study was carried out in sheep with pacing-induced atrial dilatation to validate our intracardiac inverse mapping approach. ConstellationTM 64 channel catheters with different diameters were introduced into the right and left atrium (RA & LA) or both to record atrial electrograms, with only a few electrodes in contact with the atrial wall. Endocardial electrograms were then recovered from the recordings using our inverse mapping approach, and these results confirm our computational proof-of-concept analysis firmly. Inverse potential maps across RA and LA were reconstructed repeatedly with different catheters at various locations. Consistent activation times were estimated from most reconstructed electrograms and panoramic activation time maps were physiologically realistic. Amplitudes of reconstructed electrograms were nonuniform regionally. Electrograms in regions where the mapping catheter was close to the wall were all reconstructed with large amplitudes. The morphology was similar to contact recordings, and the timing of depolarization was matched closely. On the contrary, with mapping electrodes distant from atrial wall, electrograms in the corresponding regions were relatively poorly reconstructed. The proposed intracardiac inverse approach proved that it can provide flexible and robust 3D atrial electro-anatomic mapping with a noncontact open basket catheter. Potentially, this approach can be used to improve our understanding of the mechanisms underlying AF, and guide catheter ablation for patients with AF to achieve higher success rate.