Endocardial mapping of atrial fibrillation in the human right atrium using a non-contact catheter

Abstract

Background Endocardial mapping of atrial fibrillation in humans is limited by its low resolution and by complexities in the arrhythmia and atrial anatomy. Methods and ResultsA catheter mounted non-contact multielectrode was deployed in the right atrium of 11 patients with atrial fibrillation and used to reconstruct 3360 electrograms, superimposed onto a computer-simulated model of the endocardium, using inverse solution mathematics. This allows construction of isopotential maps of the right atrium. Patients had either sustained atrial fibrillation (n=3) for >6 months or developed atrial fibrillation during the study (n=8). Spontaneous initiation of atrial fibrillation was recorded in one patient and was demonstrated by the non-contact system to arise from two successive atrial ectopic beats from the site of a roving contact catheter. Reconstruction of electrograms recorded during atrial fibrillation was validated by comparison with contact electrograms with cross-correlation. During established atrial fibrillation, four patients predominantly had a single right atrial wave front, two had two wave fronts and five patients had three to five wave fronts for most of the time. Periods of electrical silence were seen in the right atrium in eight patients, after which, activity emerged from consistent septal sites alone, suggesting a left atrial origin. During intravenous administration of flecainide, atrial fibrillation in two patients terminated spontaneously or following pacing manoeuvres, while in the remaining patient sinus rhythm was restored via atrial tachycardia.Conclusion Non-contact mapping of the right atrium has demonstrated modes of initiation and termination of atrial fibrillation, characterized different patterns of right atrial activation in atrial fibrillation and suggests that the left atrium may sustain atrial fibrillation in some patients. Simultaneous mapping of the right and left atrium is required to further elucidate the mechanisms of human atrial fibrillation.

Characterization of Left Atrial Activation in the Intact Human Heart

“…13 Although epicardial mapping has been used extensively to assess atrial activation both in animals and intraoperatively in humans, 14 -17 access to the interatrial septum and the posterior atria between the caval and pulmonary veins has prevented complete epicardial mapping 17 and general anesthesia may influence conduction. 18 Recent publications have shown that left-to-right interatrial conduction occurs predominantly through Bachmann's bundle, 19,20 and we have previously shown that during AF, after periods of electrical silence, the RA consistently reactivates from the region of Bachmann's bundle, sometimes with additional breakthrough at the CS ostium or oval fossa. 20 Despite the difficulties in left atrial mapping noted above, the predominantly epicardial studies of LA activation 15,17 have suggested that the principal route of epicardial LA activation during SR is through Bachmann's bundle, although this was not a universal finding.…”

“…18 Recent publications have shown that left-to-right interatrial conduction occurs predominantly through Bachmann's bundle, 19,20 and we have previously shown that during AF, after periods of electrical silence, the RA consistently reactivates from the region of Bachmann's bundle, sometimes with additional breakthrough at the CS ostium or oval fossa. 20 Despite the difficulties in left atrial mapping noted above, the predominantly epicardial studies of LA activation 15,17 have suggested that the principal route of epicardial LA activation during SR is through Bachmann's bundle, although this was not a universal finding. 14,16 A recent study also identified posteroseptal pathways involved in SR activation of the LA endocardium.…”

Noncontact Mapping-Guided Catheter Ablation of Atrial Fibrillation

“…[22][23][24] The accuracy of reconstructed electrograms is decreased at a distance >40 mm from the center of the array, particularly during AF. 22 In the present study group of AF patients, the average parasternal long-axis LA diameter was only 41±6 mm on transthoracic echocardiography.…”

Inducibility of atrial fibrillation during electrophysiologic evaluation is associated with increased dispersion of atrial refractoriness

“…AF is generally considered to be maintained by multiple re-entrant wavelets of excitation that propagate in different directions around the atrial myocardium [26,27]. The maintenance of AF seems to depend on the presence of a sufficient number of small wavefronts while undergoing fractionation, collisions and coalescence over the atrial surface.…”