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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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Left: Three dimensional electroanatomic map of the left ventricle (anterior projection) displaying activation time derived from non-contact electrograms during pacing from a needle (D) located at the left ventricular apex.The figure shows earliest activation (dark blue) at the apex with gradual spreading towards the base (red). Numbers on electroanatomic map (fineprint) represent randomised locations of multipole needles (shown rightmost), which were deployed via the epicardium. Right: Panels A, B and C demonstrating transmural unipolar and bipolar contact electrograms recorded from multipole needles corresponding to sites A, B and C on the electroanatomic map. Y-axis is represented in mV. Electrodes; E1–E4  =  endocardial-epicardial unipolar recording depth; E12–E34  =  endocardial-epicardial bipolar recording depth.
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pone-0110399-g002: Left: Three dimensional electroanatomic map of the left ventricle (anterior projection) displaying activation time derived from non-contact electrograms during pacing from a needle (D) located at the left ventricular apex.The figure shows earliest activation (dark blue) at the apex with gradual spreading towards the base (red). Numbers on electroanatomic map (fineprint) represent randomised locations of multipole needles (shown rightmost), which were deployed via the epicardium. Right: Panels A, B and C demonstrating transmural unipolar and bipolar contact electrograms recorded from multipole needles corresponding to sites A, B and C on the electroanatomic map. Y-axis is represented in mV. Electrodes; E1–E4  =  endocardial-epicardial unipolar recording depth; E12–E34  =  endocardial-epicardial bipolar recording depth.

Mentions: Tissue depth related changes in unipolar electrogram amplitude and morphology depended on the distance of the recording site from the site of stimulation [Figure 2]. Corresponding bipolar electrograms from the same locations and depths indicated that small differences in unipolar morphology between adjacent electrodes contribute to marked increases in electrogram amplitude of minimally filtered bipolar signals. This increase in electrogram amplitude was preserved after high pass filtering. Conversely spatial similarities in unipolar electrogram morphology between adjacent electrode pairs resulted in a low amplitude bipolar signal.


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)

Left: Three dimensional electroanatomic map of the left ventricle (anterior projection) displaying activation time derived from non-contact electrograms during pacing from a needle (D) located at the left ventricular apex.The figure shows earliest activation (dark blue) at the apex with gradual spreading towards the base (red). Numbers on electroanatomic map (fineprint) represent randomised locations of multipole needles (shown rightmost), which were deployed via the epicardium. Right: Panels A, B and C demonstrating transmural unipolar and bipolar contact electrograms recorded from multipole needles corresponding to sites A, B and C on the electroanatomic map. Y-axis is represented in mV. Electrodes; E1–E4  =  endocardial-epicardial unipolar recording depth; E12–E34  =  endocardial-epicardial bipolar recording depth.
© Copyright Policy
Related In: Results  -  Collection

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

pone-0110399-g002: Left: Three dimensional electroanatomic map of the left ventricle (anterior projection) displaying activation time derived from non-contact electrograms during pacing from a needle (D) located at the left ventricular apex.The figure shows earliest activation (dark blue) at the apex with gradual spreading towards the base (red). Numbers on electroanatomic map (fineprint) represent randomised locations of multipole needles (shown rightmost), which were deployed via the epicardium. Right: Panels A, B and C demonstrating transmural unipolar and bipolar contact electrograms recorded from multipole needles corresponding to sites A, B and C on the electroanatomic map. Y-axis is represented in mV. Electrodes; E1–E4  =  endocardial-epicardial unipolar recording depth; E12–E34  =  endocardial-epicardial bipolar recording depth.
Mentions: Tissue depth related changes in unipolar electrogram amplitude and morphology depended on the distance of the recording site from the site of stimulation [Figure 2]. Corresponding bipolar electrograms from the same locations and depths indicated that small differences in unipolar morphology between adjacent electrodes contribute to marked increases in electrogram amplitude of minimally filtered bipolar signals. This increase in electrogram amplitude was preserved after high pass filtering. Conversely spatial similarities in unipolar electrogram morphology between adjacent electrode pairs resulted in a low amplitude bipolar signal.

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