A New Dimension in EP
Accurate Diagnosis and Efficient Workflow in AF Therapy
Catheter ablation of atrial fibrillation (AF) has shown steady growth over the past two decades with almost 15 per cent annual increase in the US.1 This has led to a larger spectrum of AF patients with more complex atrial substrates being offered ablation.1
The complexities and heterogeneity of AF mechanisms challenged operators to optimize ablation strategies.1 While focal triggers from the pulmonary veins (PV) may be the dominant one in paroxysmal AF, multiple mechanisms often coexist in patients with persistent AF, with variable processes accounting for the initiation and perpetuation of AF. Additionally, so far, no consensus has been reached when it comes to the question how exactly AF episodes are sustained.1
Although pulmonary vein isolation (PVI) is quite effective in treating paroxysmal AF, the results for persistent AF remain unsatisfying. AF sources can be widely distributed in patient-specific locations, often remote from PV, in the right atrium and stable for prolonged periods of time.2 Therefore, there seems to be the need for a more individualized, selective approach to persistent AF.3
Problems of conventional mapping
There are several issues with conventional contact mapping when it comes to AF ablations:
- Conventional technologies rely on an analysis of voltage and suffer from the limitations of bipolar electrograms.
- The use of conventional catheters leads to limited spatial and temporal resolution.1
- Conventional mapping is corrupted from far-field signals.1
In addition, tissue contact with the catheter during mapping can provoke arrhythmia, which would have stayed non-clinical under normal circumstances – leading to unnecessary ablations. On the other hand, contact with the tissue can also terminate the relevant clinical arrhythmia.
Chances of emerging technologies
Thanks to advances in mapping technology, recent searches for alternative or adjunctive ablation strategies have included real-time mapping and ablation of potential AF sources.1
The ablation of non-PV triggers in addition to PVI can improve the outcome of persistent AF.3 Emerging technologies like high-resolution mapping, focal impulse and rotor modulation are strongly expected to enhance the effectiveness of catheter ablation for persistent AF.3 This is due to the fact that they allow for precise mapping of other foci outside of the pulmonary veins and can deliver a much better temporal and spatial resolution of the mapped area.4
Given the continuously changing patterns of activation, sequential mapping of AF is challenging when conventional contact catheters are used. The instantaneous and global nature of non-contact mapping may help to elucidate the underlying patient-specific mechanisms contributing to the perpetuation of AF.4
There are indications that irregular and active triggers during AF can be mapped and ablated successfully.5,6 Understanding patient-specific, non-PV mechanisms in persistent AF is essential to establish effective ablation strategies that improve clinical outcomes.3
The AcQMap System uses a mapping algorithm based on charge density instead of voltage to create a high-resolution 3D map in real-time. It is especially useful when planning complex procedures for patients with unstable rhythms. The system allows for non-contact imaging of the cardiac anatomy, more specifically global, simultaneous beat-to-beat mapping of spontaneous or unstable atrial arrhythmias. The non-contact real-time mapping can uncover distinct conduction patterns and thereby enable electrophysiologists (EPs) to plan individualized ablation strategies to address those dynamic activation patterns.
The AcQMap 3D Mapping and Imaging catheter uses 48 omnidirectional ultrasound transducers that produce 115,000 ultrasound points per minute to create a high-resolution 3D visualization of the full-chamber electrical activity. Nevertheless, the system is also capable to execute classic contact-mapping, which can be sufficient for e.g. PVI. Using the AcQMap system arrhythmias can be mapped in three minutes or less. This, in turn, allows EPs to use it to employ an efficient map-ablate-remap strategy and quickly assess ablation effectiveness. The technology of charge mapping makes it possible to visualize more details than with voltage-based maps and identify non-PV targets, to see more beyond foci and rotation.
Further improvements of charge mapping could allow widespread adaption of the technology for mapping of irregular arrhythmias.5
- Sommer, P., Rhythmologische Besonderheiten bei COVID-19-Patienten. Webinar at Deutsche Gesellschaft für Kardiologie, Herz- und Kreislaufforschung. dgk.meta-dcr.com/kardiovaskulaere-erkrankungen-in-den-zeiten-von-corona/crs/rhythmologische-besonderheiten-bei-covid-19-patienten, May 13 2020. (Accessed July 16 2020)
- Stern S. Electrocardiogram: still the cardiologist's best friend. Circulation. 2006;113(19):e753-e756. doi:10.1161/CIRCULATIONAHA.106.623934
- Berruezo, A. (2010). Complex ventricular arrhythmias: a therapeutic nightmare. Heart, 96(9), 723–728. doi:10.1136/hrt.2008.163337
- Compagnucci P, Volpato G, Falanga U, et al. Recent advances in three-dimensional electroanatomical mapping guidance for the ablation of complex atrial and ventricular arrhythmias [published online ahead of print, 2020 May 26]. J Interv Card Electrophysiol. 2020;10.1007/s10840-020-00781-3. doi:10.1007/s10840-020-00781-3
- Aryana A. Novel and Emerging Tools and Technologies in Cardiac Electrophysiology: What's on the Horizon in 2020? J Innov Card Rhythm Manag 2019; 10: 3944-3948.
- Koutalas E, Rolf S, Dinov B, et al. Contemporary Mapping Techniques of Complex Cardiac Arrhythmias - Identifying and Modifying the Arrhythmogenic Substrate. Arrhythm Electrophysiol Rev. 2015;4(1):19-27. doi:10.15420/aer.2015.4.1.19
- Willems S et al. Targeting Nonpulmonary Vein Sources in Persistent Atrial Fibrillation Identified by Noncontact Charge Density Mapping: UNCOVER AF Trial. Circ Arrhythm Electrophysiol 2019; 12:e007233.
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