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Spatial characterization of electrogram morphology from transmural recordings in the intact normal heart.

Pouliopoulos J, Chik W, Byth K, Wallace E, Kovoor P, Thiagalingam A - PLoS ONE (2014)

Bottom Line: Increasing distance from the pacing sites led to significant (p<0.01) attenuation of UEs (V-P = 7.0±0.5%; VP-P = 5.4±0.3% per cm).Attenuation of BE with distance was insignificant (Vp-p unfiltered = 2.2±0.5%; filtered = 1.7±1.4% per cm).Independent of pacing depth, significant (p<0.01) transmural electrophysiological gradients were observed, with highest amplitude occurring at epicardial layers for UE and endocardial layers for BE.

View Article: PubMed Central - PubMed

Affiliation: Department of Cardiology, Westmead Hospital, Sydney, Australia; The University of Sydney, Sydney, Australia.

ABSTRACT

Purpose: Unipolar (UE) and bipolar electrograms (BE) are utilized to identify arrhythmogenic substrate. We quantified the effect of increasing distance from the source of propagation on local electrogram amplitude; and determined if transmural electrophysiological gradients exist with respect to propagation and stimulation depth.

Methods: Mapping was performed on 5 sheep. Deployment of >50 quadripolar transmural needles in the LV were located in Cartesian space using Ensite. Contact electrograms from all needles were recorded during multisite bipolar pacing from epicardial then endocardial electrodes. Analysis was performed to determine stimulus distance to local activation time, peak negative amplitude (V-P), and peak-peak amplitude (VP-P) for (1) unfiltered UE, and (2) unfiltered and 30 Hz high-pass filtered BEs. Each sheep was analysed using repeated ANOVA.

Results: Increasing distance from the pacing sites led to significant (p<0.01) attenuation of UEs (V-P = 7.0±0.5%; VP-P = 5.4±0.3% per cm). Attenuation of BE with distance was insignificant (Vp-p unfiltered = 2.2±0.5%; filtered = 1.7±1.4% per cm). Independent of pacing depth, significant (p<0.01) transmural electrophysiological gradients were observed, with highest amplitude occurring at epicardial layers for UE and endocardial layers for BE. Furthermore, during pacing, propagation was earlier at the epicardium than endocardial layer by 1.6±2.0 ms (UE) and 1.4±2.8 ms (BE) (all p>0.01) during endocardial stimulation, and 2.3±2.4 ms (UE) and 1.8±3.7 ms (BE) during epicardal stimulation (all p<0.01).

Conclusions: Electrogram amplitude is inversely proportional to propagation distance for unipolar modalities only, which affected V-P>VP-P. Conduction propagates preferentially via the epicardium during stimulation and is believed to contribute to a transmural amplitude gradient.

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Plots showing effect of recording distance from stimulation source and recording depth on contact electrograms measured during multisite pacing of left ventricular myocardium.There was a significant inverse relationship between recording distance from stimulus location and unipolar electrogram amplitude that was not significant for bipolar electrograms. Values represent between-sheep mean ± S.E, where; p↔ is the probability of effects relative to propagation distance; and p↕ is probability of transmural effects. A. Unipolar V-P; B. Unipolar VP-P; C. Bipolar VP-P; and D. Filtered bipolar VP-P. See figure 1 for electrode locations.
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pone-0110399-g003: Plots showing effect of recording distance from stimulation source and recording depth on contact electrograms measured during multisite pacing of left ventricular myocardium.There was a significant inverse relationship between recording distance from stimulus location and unipolar electrogram amplitude that was not significant for bipolar electrograms. Values represent between-sheep mean ± S.E, where; p↔ is the probability of effects relative to propagation distance; and p↕ is probability of transmural effects. A. Unipolar V-P; B. Unipolar VP-P; C. Bipolar VP-P; and D. Filtered bipolar VP-P. See figure 1 for electrode locations.

Mentions: Increasing distances from the pacing sites resulted in significant attenuation of both V-p and VP-P for unipolar electrograms recorded during multisite pacing in 5/5 and 4/5 sheep respectively. (Figure 3 and Table 1). Whilst this effect was observed to a smaller degree on filtered and unfiltered bipolar electrograms it did not reach statistical significance. Attenuation of amplitude with increased distance was far more dramatic and consistent for unipolar electrograms (Figures 2 and, 3; Tables 1 and 2).


Spatial characterization of electrogram morphology from transmural recordings in the intact normal heart.

Pouliopoulos J, Chik W, Byth K, Wallace E, Kovoor P, Thiagalingam A - PLoS ONE (2014)

Plots showing effect of recording distance from stimulation source and recording depth on contact electrograms measured during multisite pacing of left ventricular myocardium.There was a significant inverse relationship between recording distance from stimulus location and unipolar electrogram amplitude that was not significant for bipolar electrograms. Values represent between-sheep mean ± S.E, where; p↔ is the probability of effects relative to propagation distance; and p↕ is probability of transmural effects. A. Unipolar V-P; B. Unipolar VP-P; C. Bipolar VP-P; and D. Filtered bipolar VP-P. See figure 1 for electrode locations.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4215922&req=5

pone-0110399-g003: Plots showing effect of recording distance from stimulation source and recording depth on contact electrograms measured during multisite pacing of left ventricular myocardium.There was a significant inverse relationship between recording distance from stimulus location and unipolar electrogram amplitude that was not significant for bipolar electrograms. Values represent between-sheep mean ± S.E, where; p↔ is the probability of effects relative to propagation distance; and p↕ is probability of transmural effects. A. Unipolar V-P; B. Unipolar VP-P; C. Bipolar VP-P; and D. Filtered bipolar VP-P. See figure 1 for electrode locations.
Mentions: Increasing distances from the pacing sites resulted in significant attenuation of both V-p and VP-P for unipolar electrograms recorded during multisite pacing in 5/5 and 4/5 sheep respectively. (Figure 3 and Table 1). Whilst this effect was observed to a smaller degree on filtered and unfiltered bipolar electrograms it did not reach statistical significance. Attenuation of amplitude with increased distance was far more dramatic and consistent for unipolar electrograms (Figures 2 and, 3; Tables 1 and 2).

Bottom Line: Increasing distance from the pacing sites led to significant (p<0.01) attenuation of UEs (V-P = 7.0±0.5%; VP-P = 5.4±0.3% per cm).Attenuation of BE with distance was insignificant (Vp-p unfiltered = 2.2±0.5%; filtered = 1.7±1.4% per cm).Independent of pacing depth, significant (p<0.01) transmural electrophysiological gradients were observed, with highest amplitude occurring at epicardial layers for UE and endocardial layers for BE.

View Article: PubMed Central - PubMed

Affiliation: Department of Cardiology, Westmead Hospital, Sydney, Australia; The University of Sydney, Sydney, Australia.

ABSTRACT

Purpose: Unipolar (UE) and bipolar electrograms (BE) are utilized to identify arrhythmogenic substrate. We quantified the effect of increasing distance from the source of propagation on local electrogram amplitude; and determined if transmural electrophysiological gradients exist with respect to propagation and stimulation depth.

Methods: Mapping was performed on 5 sheep. Deployment of >50 quadripolar transmural needles in the LV were located in Cartesian space using Ensite. Contact electrograms from all needles were recorded during multisite bipolar pacing from epicardial then endocardial electrodes. Analysis was performed to determine stimulus distance to local activation time, peak negative amplitude (V-P), and peak-peak amplitude (VP-P) for (1) unfiltered UE, and (2) unfiltered and 30 Hz high-pass filtered BEs. Each sheep was analysed using repeated ANOVA.

Results: Increasing distance from the pacing sites led to significant (p<0.01) attenuation of UEs (V-P = 7.0±0.5%; VP-P = 5.4±0.3% per cm). Attenuation of BE with distance was insignificant (Vp-p unfiltered = 2.2±0.5%; filtered = 1.7±1.4% per cm). Independent of pacing depth, significant (p<0.01) transmural electrophysiological gradients were observed, with highest amplitude occurring at epicardial layers for UE and endocardial layers for BE. Furthermore, during pacing, propagation was earlier at the epicardium than endocardial layer by 1.6±2.0 ms (UE) and 1.4±2.8 ms (BE) (all p>0.01) during endocardial stimulation, and 2.3±2.4 ms (UE) and 1.8±3.7 ms (BE) during epicardal stimulation (all p<0.01).

Conclusions: Electrogram amplitude is inversely proportional to propagation distance for unipolar modalities only, which affected V-P>VP-P. Conduction propagates preferentially via the epicardium during stimulation and is believed to contribute to a transmural amplitude gradient.

Show MeSH