Mapping & Ablation19Novel global ultrasound imaging and continuous dipole density mapping: initial findings in AF patients20Low voltage functional myocardium is critical in determining the substrate of post-ablation atrial tachycardia: results from a prospective study using ripple mapping distinguishing low-voltage scar from conducting tissue21Ripple mapping of post infarct ventricular scar to identify conduction channels and guide substrate based ablation22Effect of chamber geometry and activation pattern on optimal local activation time sampling density for tachycardia diagnosis25Clinical measures of good basket placement predict successful outcome from atrial fibrillation rotor ablation26Unipolar electrogram amplitude is reduced at rotor sites critical to focal termination of human persistent AF27Cryoballoon versus point by point radiofrequency ablation or a novel combined approach: long term follow up and comparison of patterns of pulmonary vein reconnection between different ablation strategies in a randomised controlled trial28Recurrent high dominant frequency patterns in persistent atrial fibrillation29Optimisation of late gadolinium enhanced (LGE) cmr imaging of atrial ablation scar30Hyperacute and chronic changes in cerebral magnetic resonance images after PVAC, NMARQ and epicardial thoracoscopic surgical ablation for paroxysmal atrial fibrillation

Introduction: Electro-anatomic mapping is standard practice in AF ablation procedures.Virtual anatomies are created to locate structures and navigate catheters and voltage (V) is used to map arrhythmias.We report on the initial findings with a new system using Ultrasound (U/S) and Dipole Density (DD) to globally image the anatomy and continuously map AF.Methods: A novel non-contact imaging and mapping system (AcQMap), consisting of a basket catheter (48 U/S transducers, 48 electrodes) and console, simultaneously acquires 100,000þ U/S points/ min to reconstruct the chamber anatomy and 150,000 intracardiac unipolar voltage (V) samples per second to map cardiac activity.The 3D surface is algorithmically reconstructed from the U/S point-set with mesh-density comparable to a segmented CT (sCT).Inverse and Forward algorithms are applied on intracardiac V to derive and display electrical activation as Dipole Density and unipolar Voltage maps, respectively, upon the ultrasound-constructed 3D anatomy (Figure).Global data is acquired simultaneously and derived continuously from single-beats or single-cycles (for AF) in real-time.Maps are displayed as a dynamic animation using the standard "thermal" colour-scale, with the colour-band set to a narrow width and positioned slightly below the baseline, at 2% of the peak-negative value (see map colour-legend).This colour setting depicts the negative phase of Dipole Density and Voltage as a red region that, when animated, is associated with propagation of depolarization.Patients undergoing ablation of AF were consented for U/S and DD mapping.U/S Left atrial anatomy was compared from full and sub-sampled point-sets and compared to pre-procedure sCT.DD and V maps were derived for each patient and depolarized surface areas were compared.Results: Seven patients (57% Male, mean age 61.4 + 10.3 yrs, AF duration 4.2 + 2.3 yrs) were enrolled.Complete data sets were collected in 6 subjects.LA surface acquisition times were 8.48 + 5.0 min.Surface acquisition must be performed for at least 30 seconds to achieve a consistent median distance between AcQMap and sCT surfaces.In the latter 4 subjects comprising initial experience in the second laboratory, consecutive acquisition times decreased from 6:39 to 4:07 minutes.The absolute median distance between surfaces was 2.71 mm.During AF, the mean depolarized area for DD maps was 26.9 cm 2 , significantly less than for V maps (110.6 cm 2 , p , 0.001).Overall V:DD ratio was 4.11 for AF.Conclusions: Real-time U/S based LA reconstruction was rapid and compared favourably to sCT.DD map provides 4.11 times higher resolution than V maps.The combination of CT-quality anatomy and DD mapping opens the possibility to map AF with more precision to identify areas of interest as potential ablation targets.