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A three-dimensional human atrial model with fiber orientation. Electrograms and arrhythmic activation patterns relationship.

Tobón C, Ruiz-Villa CA, Heidenreich E, Romero L, Hornero F, Saiz J - PLoS ONE (2013)

Bottom Line: The model includes a realistic geometry with fiber orientation, anisotropic conductivity and electrophysiological heterogeneity.We simulated different tachyarrhythmic episodes applying both transient and continuous ectopic activity.Our results also show: (1) electrograms with potentials without negative deflection related to spiral or curved wavefronts that pass over the recording point and move away, (2) potentials with a much greater proportion of positive deflection than negative in areas of wave collisions, (3) double potentials related with wave fragmentations or blocking lines and (4) fragmented electrograms associated with pivot points.

View Article: PubMed Central - PubMed

Affiliation: Instituto Interuniversitario de Investigación en Bioingeniería y Tecnología Orientada al Ser Humano (I3BH), Universitat Politècnica de València, Valencia, Spain.

ABSTRACT
The most common sustained cardiac arrhythmias in humans are atrial tachyarrhythmias, mainly atrial fibrillation. Areas of complex fractionated atrial electrograms and high dominant frequency have been proposed as critical regions for maintaining atrial fibrillation; however, there is a paucity of data on the relationship between the characteristics of electrograms and the propagation pattern underlying them. In this study, a realistic 3D computer model of the human atria has been developed to investigate this relationship. The model includes a realistic geometry with fiber orientation, anisotropic conductivity and electrophysiological heterogeneity. We simulated different tachyarrhythmic episodes applying both transient and continuous ectopic activity. Electrograms and their dominant frequency and organization index values were calculated over the entire atrial surface. Our simulations show electrograms with simple potentials, with little or no cycle length variations, narrow frequency peaks and high organization index values during stable and regular activity as the observed in atrial flutter, atrial tachycardia (except in areas of conduction block) and in areas closer to ectopic activity during focal atrial fibrillation. By contrast, cycle length variations and polymorphic electrograms with single, double and fragmented potentials were observed in areas of irregular and unstable activity during atrial fibrillation episodes. Our results also show: (1) electrograms with potentials without negative deflection related to spiral or curved wavefronts that pass over the recording point and move away, (2) potentials with a much greater proportion of positive deflection than negative in areas of wave collisions, (3) double potentials related with wave fragmentations or blocking lines and (4) fragmented electrograms associated with pivot points. Our model is the first human atrial model with realistic fiber orientation used to investigate the relationship between different atrial arrhythmic propagation patterns and the electrograms observed at more than 43000 points on the atrial surface.

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Flutter and reentrant tachycardia episodes. Snapshots, APs, EGM and spectral analysis in selected points.(A) Atrial flutter and (B) reentrant tachycardia episodes. In the snapshots, the color scale represents the range of values of the AP in mV. The depolarizing front is identified by the red color. The black arrow indicates the wavefront direction and the dash line a blocking line. AP time-courses of selected sites (indicated in the snapshots) are showed at the left, the dotted arrows indicate the activation sequence. EGM and their spectral analysis showing DF and OI values are shown (See text for more details).
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pone-0050883-g005: Flutter and reentrant tachycardia episodes. Snapshots, APs, EGM and spectral analysis in selected points.(A) Atrial flutter and (B) reentrant tachycardia episodes. In the snapshots, the color scale represents the range of values of the AP in mV. The depolarizing front is identified by the red color. The black arrow indicates the wavefront direction and the dash line a blocking line. AP time-courses of selected sites (indicated in the snapshots) are showed at the left, the dotted arrows indicate the activation sequence. EGM and their spectral analysis showing DF and OI values are shown (See text for more details).

Mentions: Figure 5A depicts an example of AFL obtained by applying the burst of six ectopic beats in the isthmus of RA (near the CS), 231 ms after the last sinus stimulus. When the burst was applied, a conduction block was observed in the CS area which induced a macroreentry rotating counterclockwise around the tricuspid annulus (see the arrow in snapshot at 4100 ms in Figure 5A), that was maintained during the whole simulation (≈8 seconds). The activation pattern of this macroreentry resembles an AFL (see video S1 in the Supporting Information). The direction of the reentrant circuit can also be observed when comparing the APs of the sites 1, 2 and 3 in Figure 5A (see dotted arrows). The macrorentrant wavefront depolarized the rest of the atria, including the posterior wall of the LA (see site 4 in Figure 5A) with a 1∶1 activation pattern. The CL of this arrhythmic pattern was almost constant (≈200 ms) in the whole atria, a characteristic of AFL. The EGM in different points of the atria (see sites 2 and 4 in Figure 5A) only displayed single potentials, showing a stable and regular atrial activation, which is also characteristic of AFL. This regularity is reflected as a single narrow DF peak of 5.0 Hz and high OI values, close to unity, in sites 2 and 4. Similar DF and OI values were observed in the entire atrial tissue.


A three-dimensional human atrial model with fiber orientation. Electrograms and arrhythmic activation patterns relationship.

Tobón C, Ruiz-Villa CA, Heidenreich E, Romero L, Hornero F, Saiz J - PLoS ONE (2013)

Flutter and reentrant tachycardia episodes. Snapshots, APs, EGM and spectral analysis in selected points.(A) Atrial flutter and (B) reentrant tachycardia episodes. In the snapshots, the color scale represents the range of values of the AP in mV. The depolarizing front is identified by the red color. The black arrow indicates the wavefront direction and the dash line a blocking line. AP time-courses of selected sites (indicated in the snapshots) are showed at the left, the dotted arrows indicate the activation sequence. EGM and their spectral analysis showing DF and OI values are shown (See text for more details).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3569461&req=5

pone-0050883-g005: Flutter and reentrant tachycardia episodes. Snapshots, APs, EGM and spectral analysis in selected points.(A) Atrial flutter and (B) reentrant tachycardia episodes. In the snapshots, the color scale represents the range of values of the AP in mV. The depolarizing front is identified by the red color. The black arrow indicates the wavefront direction and the dash line a blocking line. AP time-courses of selected sites (indicated in the snapshots) are showed at the left, the dotted arrows indicate the activation sequence. EGM and their spectral analysis showing DF and OI values are shown (See text for more details).
Mentions: Figure 5A depicts an example of AFL obtained by applying the burst of six ectopic beats in the isthmus of RA (near the CS), 231 ms after the last sinus stimulus. When the burst was applied, a conduction block was observed in the CS area which induced a macroreentry rotating counterclockwise around the tricuspid annulus (see the arrow in snapshot at 4100 ms in Figure 5A), that was maintained during the whole simulation (≈8 seconds). The activation pattern of this macroreentry resembles an AFL (see video S1 in the Supporting Information). The direction of the reentrant circuit can also be observed when comparing the APs of the sites 1, 2 and 3 in Figure 5A (see dotted arrows). The macrorentrant wavefront depolarized the rest of the atria, including the posterior wall of the LA (see site 4 in Figure 5A) with a 1∶1 activation pattern. The CL of this arrhythmic pattern was almost constant (≈200 ms) in the whole atria, a characteristic of AFL. The EGM in different points of the atria (see sites 2 and 4 in Figure 5A) only displayed single potentials, showing a stable and regular atrial activation, which is also characteristic of AFL. This regularity is reflected as a single narrow DF peak of 5.0 Hz and high OI values, close to unity, in sites 2 and 4. Similar DF and OI values were observed in the entire atrial tissue.

Bottom Line: The model includes a realistic geometry with fiber orientation, anisotropic conductivity and electrophysiological heterogeneity.We simulated different tachyarrhythmic episodes applying both transient and continuous ectopic activity.Our results also show: (1) electrograms with potentials without negative deflection related to spiral or curved wavefronts that pass over the recording point and move away, (2) potentials with a much greater proportion of positive deflection than negative in areas of wave collisions, (3) double potentials related with wave fragmentations or blocking lines and (4) fragmented electrograms associated with pivot points.

View Article: PubMed Central - PubMed

Affiliation: Instituto Interuniversitario de Investigación en Bioingeniería y Tecnología Orientada al Ser Humano (I3BH), Universitat Politècnica de València, Valencia, Spain.

ABSTRACT
The most common sustained cardiac arrhythmias in humans are atrial tachyarrhythmias, mainly atrial fibrillation. Areas of complex fractionated atrial electrograms and high dominant frequency have been proposed as critical regions for maintaining atrial fibrillation; however, there is a paucity of data on the relationship between the characteristics of electrograms and the propagation pattern underlying them. In this study, a realistic 3D computer model of the human atria has been developed to investigate this relationship. The model includes a realistic geometry with fiber orientation, anisotropic conductivity and electrophysiological heterogeneity. We simulated different tachyarrhythmic episodes applying both transient and continuous ectopic activity. Electrograms and their dominant frequency and organization index values were calculated over the entire atrial surface. Our simulations show electrograms with simple potentials, with little or no cycle length variations, narrow frequency peaks and high organization index values during stable and regular activity as the observed in atrial flutter, atrial tachycardia (except in areas of conduction block) and in areas closer to ectopic activity during focal atrial fibrillation. By contrast, cycle length variations and polymorphic electrograms with single, double and fragmented potentials were observed in areas of irregular and unstable activity during atrial fibrillation episodes. Our results also show: (1) electrograms with potentials without negative deflection related to spiral or curved wavefronts that pass over the recording point and move away, (2) potentials with a much greater proportion of positive deflection than negative in areas of wave collisions, (3) double potentials related with wave fragmentations or blocking lines and (4) fragmented electrograms associated with pivot points. Our model is the first human atrial model with realistic fiber orientation used to investigate the relationship between different atrial arrhythmic propagation patterns and the electrograms observed at more than 43000 points on the atrial surface.

Show MeSH
Related in: MedlinePlus