Non-contact whole-chamber charge density mapping of the left ventricle: preclinical evaluation in a sheep model

Abstract Funding Acknowledgements Type of funding sources: Public hospital(s). Main funding source(s): Oxford Biomedical Research Centre Introduction Non-contact charge density mapping allows visualisation of whole chamber propagation during atrial fibrillation (AF). The identification of regions with repetitive or, conversely, more complex patterns of wavefront propagation may provide clues to mechanisms responsible for AF maintenance and lead to improved outcomes from catheter ablation. Our novel mapping approach based on signal recurrence plots has never been applied to whole chamber, bi-atrial recording of atrial fibrillation. Purpose To apply recurrence analysis to characterise whole chamber bi-atrial AF propagation. Methods Non-contact dipole signals from left and right atrial maps were obtained during simultaneous bi-atrial charge density mapping of AF. Signals were converted to phase and mean phase coherence calculated for the generation of recurrence distance matrices for the whole chamber and each anatomical region (6x LA and 4x RA) over the 30-second recording duration, where a value of 1 (purple, see figure panel A) represents uniform repetitive conduction, and 0 (red), irregular, non-repetitive activity. Whole chamber and regional mean recurrence values were calculated and correlated with the frequency of wavefronts of localised irregular activation patterns. Results Maps were obtained prior to ablation in 21 patients (5 paroxysmal (pAF), 16 persistent AF (persAF)) undergoing de-novo catheter ablation procedures. Whole chamber recurrence was higher in patients with pAF (0.40 ± 0.08) than persAF (0.34 ± 0.05), p < 0.0005. There was an inverse correlation between regional recurrence values and the number of localised irregular activations detected (-0.7021, p < 0.0005, figure panel B) with the lateral LA and anterior RA demonstrating the highest recurrence values in each chamber (figure panel C). Conclusion Use of recurrence distance matrices characterises global AF propagation phenotypes. Regional values are inversely correlated with the frequency of localised irregular activation patterns identified demonstrating an anatomic dependence in the level of AF propagation complexity, greatest in the anterior LA and septal RA. Comparison of strategies targeting regions with maximal vs. minimal values during catheter ablation may define an optimal approach to treatment of persistent AF. Abstract Figure. Recurrence abstract figure

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P1053Higher density mapping efficiency and ease of maneuverability of a novel mapping catheter in complex arrhythmias

EP Europace ◽

10.1093/europace/euaa162.313 ◽

2020 ◽

Vol 22 (Supplement_1) ◽

Author(s):

A Sarkozy ◽

J V Vijgen ◽

T D De Potter ◽

R S Schilling ◽

V M Markides

Keyword(s):

Left Ventricle ◽

Primary Endpoint ◽

Ease Of Use ◽

Serious Adverse Events ◽

Density Mapping ◽

Post Procedure ◽

Fast Activation ◽

Multi Center Study ◽

Met Expectations ◽

Mapping Catheter

Abstract Background An advanced mapping catheter has been developed to facilitate reliable identification of ablation targets in complex arrythmias. This catheter has 48 platinum-iridium mapping electrodes, with 6 of those electrodes distributed across each of the 8 spines (Figure). Purpose To assess the mapping efficiency of the catheter in a feasibility study and characterize the ease of use through physician feedback. Methods This prospective, single arm, non-randomized, multi-center study was conducted at 5 European sites. The primary endpoint was the completion of protocol required fast activation and electro anatomical pre-ablation mapping. Catheter performance regarding its deployment, ease of use, and mapping results was assessed via a post procedure physician feedback survey. Physician feedback rated as ≥4 on the 7-point Likert scale (1 = poor, 7= excellent) indicated that the catheter met expectations. Subjects were followed 7 days post procedure for serious adverse events (SAEs). Results Thirty-one patients (age: 67.8 ± 8.52 years, 87.1% men) were enrolled (11 ventricular tachycardia [VT], 10 scar-related AT/re-do paroxysmal AF [PAF], 10 persistent AF[PsAF]). 28 subjects had study catheter inserted for mapping purposes. The primary endpoint was achieved in 23/28 patients (82.1%). Five patients did not complete pre-ablation mapping requirements due to physicians’ choice as voltage mapping was considered sufficient (N = 3), inability of catheter to reach the basal inferior septal left ventricle (N = 1), and physician’s decision to perform pulmonary vein isolation prior to protocol-required mapping (N = 1). Pre-ablation median mapping times (Q1/Q3) were 121.0 (71.0, 146.0), 72.5 (51.0, 107.0), and 31.5 (13.5, 48.0) minutes for the VT, AT/PAF, and PsAF groups, respectively. Median total procedure times for VT, AT/PAF, and PsAF were 192, 193 and 146 minutes, respectively. Median points acquired per minute were 24.4, 43.6, and 69.8 for the VT, AT/PAF, and PsAF subgroups. All subjects (16/16, 100%) who had conduction channel(s), gaps(s), or critical isthmus identified had the areas appropriately mapped. The incidence of SAEs observed was low (1/30; 3.3%) with only 1 heart failure case reported. Operators rated the ability to deploy as met expectations or better (median score: 5.0, Q1/Q3 4.0,6.0). Ability to maneuver was rated very positively in the atria: the catheter met expectations or was at least comparable to other devices for 90.0% of LA and 100.0% of right atrium (RA) use. Users felt the catheter met expectations or better in its ability to reach the atria and ventricles; 85%, 100%, and 60% of users ranked the catheter with a score of ≥ 4 in the LA, RA, and left ventricle, respectively. Conclusion(s): Our results demonstrate the feasibility of the high-density mapping catheter to efficiently map complex arrythmias with a good safety profile. Post procedural operators’ feedback indicates satisfaction with the ease of use and maneuverability. Abstract Figure

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Supramolecular Stark Effect in Host-Guest Complexes via Charge Density Analysis

Acta Crystallographica Section A Foundations and Advances ◽

10.1107/s2053273314093255 ◽

2014 ◽

Vol 70 (a1) ◽

pp. C674-C674

Author(s):

Sajesh Thomas ◽

Rebecca Fuller ◽

Alexandre Sobolev ◽

Philip Schauer ◽

Simon Grabowsky ◽

...

Keyword(s):

Electric Field ◽

Charge Density ◽

Electric Fields ◽

Active Sites ◽

Stark Effect ◽

Dipole Moments ◽

Covalent Bonds ◽

Guest Molecules ◽

Density Mapping ◽

Density Analysis

The effect of an electric field on the vibrational spectra, the Vibrational Stark Effect (VSE), has been utilized extensively to probe the local electric field in the active sites of enzymes [1, 2]. For this reason, the electric field and consequent polarization effects induced by a supramolecular host system upon its guest molecules attain special interest due to the implications for various biological processes. Although the host-guest chemistry of crown ether complexes and clathrates is of fundamental importance in supramolecular chemistry, many of these multicomponent systems have yet to be explored in detail using modern techniques [3]. In this direction, the electrostatic features associated with the host-guest interactions in the inclusion complexes of halogenated acetonitriles and formamide with 18-crown-6 host molecules have been analyzed in terms of their experimental charge density distribution. The charge density models provide estimates of the molecular dipole moment enhancements which correlate with the simulated values of dipole moments under electric field. The accurate electron density mapping using the multipole formalism also enable the estimation of the electric field experienced by the guest molecules. The electric field vectors thus obtained were utilized to estimate the vibrational stark effect in the nitrile (-C≡N) and carbonyl (C=O) stretching frequencies of the guest molecules via quantum chemical calculations in gas phase. The results of these calculations indicate remarkable elongation of C≡N and C=O bonds due to the electric fields. The electronic polarization in these covalent bonds induced by the field manifests as notable red shifts in their characteristic vibrational frequencies. These results derived from the charge densities are further supported by FT-IR experiments and thus establish the significance of a phenomenon that could be termed as the "supramolecular Stark effect" in crystal environment.

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