Left atrial voltage mapping: defining and targeting the atrial fibrillation substrate

Figures

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  Fig. 1. Left atrial voltage mapping. Two examples of high density left atrial voltage maps created during AF ablation are shown using CARTO (Biosense Webster, Diamond Bar, USA) and recorded using a LassoNav catheter. Panel (a) includes 1122 points. Panel (b) includes 1489 points. In both cases, purple colour represents electrogram voltage > 0.5 mV. In (a), minimal/no LVA are present whereas in (b), there are areas of low voltage affecting the LA septum and posterior wall

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  Fig. 2. Approaches to low voltage area ablation. Strategies described by Kircher et al. [5] to individualise substrate-based ablation treatment. (a) Low voltage isolation strategy for treatment of low voltage areas, shown in light red. (b) Linear ablation across a low voltage area. (c) Homogenisation of a low voltage area

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  Fig. 3. Clinical outcomes of randomised studies comparing voltage-guided ablation to standard ablation. (a) Kaplan–Meier curves comparing individualised versus standardised substrate modification, showing arrhythmia free survival and demonstrating a statistically significant benefit for an individualised approach [10]. (b) Kaplan–Meier curves from the STABLE SR trial comparing stepwise treatment for AF with substrate-based ablation using voltage mapping, showing no evidence of benefit [11]. The figures were adapted with permission

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  Fig. 4. Extracellular field created by an activation wave-front. At the exact region of the wave-front, axial current flows from the activated tissue to the resting tissue, creating a system representative of a propagating dipole. Transmembrane current then flows out of the membrane ahead of the wave, to return at the wave-back via newly activated sodium channels, thus forming a current loop. Consequently, the extracellular field is positive ahead of the wave-front and negative behind it

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  Fig. 5. Bipolar voltage attenuation at decreasing coupling intervals: Four unique patterns found when measuring voltage amplitude during decreasing coupling intervals in patients with otherwise ‘normal’ voltage (> 0.3 mV at CL 470 ms). (a) High initial voltage without attenuation. (b) Voltage with attenuation that plateaus above 1 mV. (c) Initial low voltage without attenuation. (d) Voltage which attenuates to a low plateau (< 1 mV) [101]