Far-field effect in unipolar electrograms revisited: High-density mapping of atrial fibrillation in humans

Podziemski, Piotr; Kuklik, Paweł; Hunnik, Arne van; Zeemering, Stef; Maesen, Bart; Schotten, Ulrich

doi:10.1109/embc.2015.7319681

Cited by 6 publications

(5 citation statements)

References 12 publications

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“…Podziemski et al determined this relationship in 3D atrial tissue. The investigators used activation wave fronts that traveled along a line of conduction block . In this way, they were able to measure the amplitude of electrograms at several distances from activated tissue distal from the line of block.…”

Section: Unipolar Recording Modementioning

confidence: 99%

“…The investigators used activation wave fronts that traveled along a line of conduction block. 4 In this way, they were able to measure the amplitude of electrograms at several distances from activated tissue distal from the line of block. The authors fitted the data to an exponential function, but it can be shown that the amplitude-distance curve they composed fits well with the inverse of the distance to the power of 2 for large distances.…”

Section: Change In Signal Amplitude With Distance In 3dmentioning

confidence: 99%

“…In fact this concept uses the direction dependence of the bipolar electrogram. In case the focus is located between terminals 2 and 3, the direction of the activation fronts running to the most distal electrode(3)(4) is opposite to the direction of the front toward the most proximal pair (1-2) and these signals are inverse.…”

mentioning

confidence: 99%

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Electrogram recording and analyzing techniques to optimize selection of target sites for ablation of cardiac arrhythmias

Bakker

2019

Pacing Clinical Electrophis

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The extracellular electrogram is caused by transmembrane currents that flow into extracellular space during propagation of the electrical impulse. Electrograms are usually recorded in unipolar or bipolar mode that have different characteristics, but provide complementary information. Both recording modes have specific advantages, but also suffer from disadvantages. Techniques to circumvent some of the weaknesses are reviewed. The origin of remote and fractionated deflections and their relation with electrode characteristics are discussed. Epicardial and endocardial sites of origin and breakthrough sites as well as the effect of fatty tissue on extracellular electrograms are presented. Induction of tachycardia to assess the arrhythmogenic area is not always possible because of hemodynamic instability of the patient. Techniques to assess sites with high reentry vulnerability without induction of arrhythmias are outlined such as activation‐repolarization mapping and decremental stimulation. Pitfalls of substrate mapping and techniques to avoid them as omnipolar mapping and characterization of complex electrograms by entropy are presented. Technical aspects that influence electrogram morphology as electrode size, filtering, contact force, and catheter position are delineated. Data from the various publications suggest that a combination of unipolar and bipolar electrogram analysis techniques is helpful to optimize determination of target sites for ablation.

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Section: Unipolar Recording Modementioning

confidence: 99%

Section: Change In Signal Amplitude With Distance In 3dmentioning

confidence: 99%

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Electrogram recording and analyzing techniques to optimize selection of target sites for ablation of cardiac arrhythmias

Bakker

2019

Pacing Clinical Electrophis

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“…The amplitude of the unipolar EGM is dependent on local activation and a far‐field component which decreases by the power of 2 with distance as demonstrated by Podziemski et al 10 in three‐dimensional atrial tissue, although the exact relationship may change depending on the source of far‐field activation (i.e., focal/planar/rotational). Both components will also be reduced in the presence of myopathic structural remodeling or regional conduction block which decreases the number of depolarized myocytes under the recording electrode and its field of view.…”

Section: Discussionmentioning

confidence: 83%

Unipolar electrogram‐based voltage mapping with far‐field cancellation to improve detection of abnormal atrial substrate during atrial fibrillation

Ragot

Nayyar

Massin

et al. 2021

Cardiovasc electrophysiol

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Introduction An important substrate for atrial fibrillation (AF) is fibrotic atrial myopathy. Identifying low voltage, myopathic regions during AF using traditional bipolar voltage mapping is limited by the directional dependency of wave propagation. Our objective was to evaluate directionally independent unipolar voltage mapping, but with far‐field cancellation, to identify low‐voltage regions during AF. Methods In 12 patients undergoing pulmonary vein isolation for AF, high‐resolution voltage mapping was performed in the left atrium during sinus rhythm and AF using a roving 20‐pole circular catheter. Bipolar electrograms (EGMs) (Bi) < 0.5 mV in sinus rhythm identified low‐voltage regions. During AF, bipolar voltage and unipolar voltage maps were created, the latter with (uni‐res) and without (uni‐orig) far‐field cancellation using a novel, validated least‐squares algorithm. Results Uni‐res voltage was ~25% lower than uni‐orig for both low voltage and normal atrial regions. Far‐field EGM had a dominant frequency (DF) of 4.5–6.0 Hz, and its removal resulted in a lower DF for uni‐orig compared with uni‐res (5.1 ± 1.5 vs. 4.8 ± 1.5 Hz; p < .001). Compared with Bi, uni‐res had a significantly greater area under the receiver operator curve (0.80 vs. 0.77; p < .05), specificity (86% vs. 76%; p < .001), and positive predictive value (43% vs. 30%; p < .001) for detecting low‐voltage during AF. Similar improvements in specificity and positive predictive value were evident for uni‐res versus uni‐orig. Conclusion Far‐field EGM can be reliably removed from uni‐orig using our novel, least‐squares algorithm. Compared with Bi and uni‐orig, uni‐res is more accurate in detecting low‐voltage regions during AF. This approach may improve substrate mapping and ablation during AF, and merits further study.

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“…The decay function property is in line with the results from a surgical study in patients with paroxysmal and persistent AF. 14 Based on the experimental data of 10 sec unipolar EGMs from a high-density electrode array and a computer simulation, they observed a decay to 50% of the source unipolar EGM within 1.5 mm to 2.1 mm function. This is in the same range for the ring electrode in our study between 2 mm and 4 mm distance (140% to 70% for amplitude and 180% to 90% for the slope).…”

Section: Discussionmentioning

confidence: 99%

The Effect of Electrode-Tissue Distance on Unipolar and Bipolar Voltage Electrograms for large-Tip, Ring-, and Mini-Electrodes

Schlageter,

Luca,

Badertscher

et al. 2024

Preprint

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Background The characteristics of intracardiac unipolar and bipolar voltage electrograms (EGM) acquired by electrophysiological catheters depend on the electrode design and configuration. The aim of the study was to assess the impact of electrode design and distance from the myocardial electric source on the unipolar and bipolar intracardiac electrograms recorded with a multi-electrode ablation catheter do deduce a cut-off for far-field versus near-field discrimination. Methods We retrospectively analyzed left atrial electroanatomical maps of 25 patients performed using an ablation catheter with a 4.5 mm tip-, mini- and 2 mm ring electrodes. The unipolar and bipolar EGMs were characterized based on peak-to-peak amplitude, signal duration (width), maximal slope, and relative power of the high frequency spectrum (HF_rel). Distances of the electrode from the tissue were calculated from the electroanatomic reconstruction. Results We analyzed EGMs of 5183 catheter positions. The unipolar EGM of ring electrodes showed an increased amplitude (140%), slope (150%) and HF_rel (16% vs 11%) compared to the tip- and mini-electrodes. In contrast, for bipolar EGM, the tip-ring pair showed the largest amplitude, width, and slope. The median amplitude, slope, and HF_rel for the ring electrodes followed a power-law decay function with distance. A cut-off of 4 mm was determined for far-field versus near-field discrimination. Conclusions We showed a higher unipolar amplitude for small ring-electrodes compared to larger tip electrodes. Furthermore, a rapid decay of the amplitude, slope, and HF_rel with distance could be observed. The decay functions are suggestive for a near-field cut-off distance below 4mm from the tissue.

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Far-field effect in unipolar electrograms revisited: High-density mapping of atrial fibrillation in humans

Cited by 6 publications

References 12 publications

Electrogram recording and analyzing techniques to optimize selection of target sites for ablation of cardiac arrhythmias

Electrogram recording and analyzing techniques to optimize selection of target sites for ablation of cardiac arrhythmias

Unipolar electrogram‐based voltage mapping with far‐field cancellation to improve detection of abnormal atrial substrate during atrial fibrillation

The Effect of Electrode-Tissue Distance on Unipolar and Bipolar Voltage Electrograms for large-Tip, Ring-, and Mini-Electrodes

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