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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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Transmural comparison of activation time between the epicardial and endocardial layer (shown as difference ΔAT) at various distances from the stimulus site during endocardial and epicardial pacing.Comparisons shown are: A. Unipolar and B. Bipolar minimally filtered electrograms.
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pone-0110399-g005: Transmural comparison of activation time between the epicardial and endocardial layer (shown as difference ΔAT) at various distances from the stimulus site during endocardial and epicardial pacing.Comparisons shown are: A. Unipolar and B. Bipolar minimally filtered electrograms.

Mentions: The transmural electrophysiological gradient observed for unipolar electrograms was consistent with preferential conduction via the epicardium during left ventricular stimulation (Figure 5). During endocardial pacing, the epicardium activated earlier than the endocardium by 1.6±2.0 ms (p<0.01) for unipolar and 1.4±3.1 ms (p<0.01) for bipolar modalities. Earlier epicardial activation was also observed during epicardial pacing, with significant transmural activation time differences of 2.3±2.4 ms (p<0.01) and 1.8±3.7 ms (p<0.01) for both unipolar and bipolar modalities respectively. Respectively, during pacing, conduction velocity was greater during transmural propagation, than during propagation parallel to the ventricular wall by a ratio of 1 to 0.7.


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)

Transmural comparison of activation time between the epicardial and endocardial layer (shown as difference ΔAT) at various distances from the stimulus site during endocardial and epicardial pacing.Comparisons shown are: A. Unipolar and B. Bipolar minimally filtered electrograms.
© Copyright Policy
Related In: Results  -  Collection

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

pone-0110399-g005: Transmural comparison of activation time between the epicardial and endocardial layer (shown as difference ΔAT) at various distances from the stimulus site during endocardial and epicardial pacing.Comparisons shown are: A. Unipolar and B. Bipolar minimally filtered electrograms.
Mentions: The transmural electrophysiological gradient observed for unipolar electrograms was consistent with preferential conduction via the epicardium during left ventricular stimulation (Figure 5). During endocardial pacing, the epicardium activated earlier than the endocardium by 1.6±2.0 ms (p<0.01) for unipolar and 1.4±3.1 ms (p<0.01) for bipolar modalities. Earlier epicardial activation was also observed during epicardial pacing, with significant transmural activation time differences of 2.3±2.4 ms (p<0.01) and 1.8±3.7 ms (p<0.01) for both unipolar and bipolar modalities respectively. Respectively, during pacing, conduction velocity was greater during transmural propagation, than during propagation parallel to the ventricular wall by a ratio of 1 to 0.7.

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