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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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Illustration of electrocardiographic recording method, signal processing, and measurement of electrograms.E1–E4  =  endocardial – epicardial plunge needle electrodes. +/−  =  electrode terminals. Diff  =  differential of +/− terminals. Triangle  =  Analogue Amplifier. GND  =  Ground Terminal attached to rib-retractors. ADC =  Analogue to Digital Converter (1 kHz sampling). Step Functions (f): Band-Pass filtering in analogue domain (0.2–300 Hz) and High-Pass filtering in the digital domain (not performed or 30 Hz). V-P  =  Maximum negative deflection amplitude of QRS complex. VP-P  =  Maximum peak positive to peak negative deflection amplitude of QRS complex.
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pone-0110399-g001: Illustration of electrocardiographic recording method, signal processing, and measurement of electrograms.E1–E4  =  endocardial – epicardial plunge needle electrodes. +/−  =  electrode terminals. Diff  =  differential of +/− terminals. Triangle  =  Analogue Amplifier. GND  =  Ground Terminal attached to rib-retractors. ADC =  Analogue to Digital Converter (1 kHz sampling). Step Functions (f): Band-Pass filtering in analogue domain (0.2–300 Hz) and High-Pass filtering in the digital domain (not performed or 30 Hz). V-P  =  Maximum negative deflection amplitude of QRS complex. VP-P  =  Maximum peak positive to peak negative deflection amplitude of QRS complex.

Mentions: A left thoracotomy was performed through the 4th intercostal space. The heart was exposed, and a grid of 50–60 multi-electrode mapping needles (0.8 mm diameter, four 1.5 mm length electrodes separated by 1.5 mm length Teflon spacers) was positioned through the anterior and lateral left ventricle (see figure 1). The needle at the top left corner of the grid was positioned immediately below the atrioventricular groove. The first row of needles was then placed along the atrioventricular groove with an inter-needle spacing of 1 cm. Subsequent rows were added at 1 cm intervals below and parallel to the first row.


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)

Illustration of electrocardiographic recording method, signal processing, and measurement of electrograms.E1–E4  =  endocardial – epicardial plunge needle electrodes. +/−  =  electrode terminals. Diff  =  differential of +/− terminals. Triangle  =  Analogue Amplifier. GND  =  Ground Terminal attached to rib-retractors. ADC =  Analogue to Digital Converter (1 kHz sampling). Step Functions (f): Band-Pass filtering in analogue domain (0.2–300 Hz) and High-Pass filtering in the digital domain (not performed or 30 Hz). V-P  =  Maximum negative deflection amplitude of QRS complex. VP-P  =  Maximum peak positive to peak negative deflection amplitude of QRS complex.
© Copyright Policy
Related In: Results  -  Collection

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

pone-0110399-g001: Illustration of electrocardiographic recording method, signal processing, and measurement of electrograms.E1–E4  =  endocardial – epicardial plunge needle electrodes. +/−  =  electrode terminals. Diff  =  differential of +/− terminals. Triangle  =  Analogue Amplifier. GND  =  Ground Terminal attached to rib-retractors. ADC =  Analogue to Digital Converter (1 kHz sampling). Step Functions (f): Band-Pass filtering in analogue domain (0.2–300 Hz) and High-Pass filtering in the digital domain (not performed or 30 Hz). V-P  =  Maximum negative deflection amplitude of QRS complex. VP-P  =  Maximum peak positive to peak negative deflection amplitude of QRS complex.
Mentions: A left thoracotomy was performed through the 4th intercostal space. The heart was exposed, and a grid of 50–60 multi-electrode mapping needles (0.8 mm diameter, four 1.5 mm length electrodes separated by 1.5 mm length Teflon spacers) was positioned through the anterior and lateral left ventricle (see figure 1). The needle at the top left corner of the grid was positioned immediately below the atrioventricular groove. The first row of needles was then placed along the atrioventricular groove with an inter-needle spacing of 1 cm. Subsequent rows were added at 1 cm intervals below and parallel to the first row.

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