High-resolution noncontact charge-density mapping of endocardial activation

Abstract

METHODS. A prototype algorithm, developed from first principles of electrostatic field theory, derives charge density (CD) as a spatial representation of the true sources of the cardiac field. The algorithm processes multiple, simultaneous, noncontact voltage measurements within the cardiac chamber to inversely derive the global distribution of CD sources across the endocardial surface. RESULTS. Comparison of CD to an established computer-simulated model of atrial conduction demonstrated feasibility in terms of spatial, temporal, and morphologic metrics. Inverse reconstruction matched simulation with median spatial errors of 1.73 mm and 2.41 mm for CD and voltage, respectively. Median temporal error was less than 0.96 ms and morphologic correlation was greater than 0.90 for both CD and voltage. Activation patterns observed in human atrial flutter reproduced those established through contact maps, with a 4-fold improvement in resolution noted for CD over voltage. Global activation maps (charge density-based) are reported in atrial fibrillation with confirmed reduction of far-field interference. Arrhythmia cycle-length slowing and termination achieved through ablation of critical points demonstrated in the maps indicates both mechanistic and pathophysiological relevance. CONCLUSION. Global maps of cardiac activation based on CD enable classification of conduction patterns and localized nonpulmonary vein therapeutic targets in atrial fibrillation. The measurement capabilities of the approach have roles spanning deep phenotyping to therapeutic application. TRIAL REGISTRATION. ClinicalTrials.gov NCT01875614.

Another method that shows organization in persistent AF? That's a RAAP

“…Similar to this study, we identified repetitive activation patterns in all patients with persistent AF at sites where AF terminated with limited ablation, using electrograms obtained from basket catheters, highly suggestive of mechanistic importance of these sites (Figure ) . The validity of these approaches is further supported by other mapping methods that show repetitive patterns using noncontact methods or using the same mapping catheter and show stability of spatiotemporal dispersion . In general, there is an agreement between many of these techniques which offer promise for future mechanistically tailored AF therapy…”

Diverse activation patterns during persistent atrial fibrillation by noncontact charge‐density mapping of human atrium

“…Voltage and charge density are intrinsically linked because the magnitude of voltage at any point is a summation across all dipolar charge that is directly proportional to the strength of each charge and inversely proportional to the distance to each charge. The charge‐density mapping system provides static and dynamic three‐dimensional (3D) maps of electrical activation across an ultrasound‐acquired cardiac chamber surface 9,10 . Further details of charge‐density mapping are discussed in the supplementary methods.…”

Novel noncontact charge density map in the setting of post-atrial fibrillation atrial tachycardias: first experience with the Acutus SuperMap Algorithm

“…Mapping such irregular rhythms is technically challenging with the current sequential 3D mapping systems and often burdensome and time-consuming, especially in case of variations of the tachycardia cycle length [7][8][9]. The AcQMap 3D imaging and mapping system (Acutus Medical, CA, USA) utilizes the unique combination of ultrasound and non-contact global electrical mapping [10,11]. The new mapping system uses ultrasound to reconstruct the atrial chamber anatomy to create a computed tomography (CT) quality like anatomy.…”