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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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Fiber orientation in the model.Frontal (A) and dorsal (B) views of the model. The model was divided into 42 areas (represented with different colors) according to the orientation of the muscle bundles (left) and fiber orientation (see black arrows) assigned to the main areas (right).
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pone-0050883-g002: Fiber orientation in the model.Frontal (A) and dorsal (B) views of the model. The model was divided into 42 areas (represented with different colors) according to the orientation of the muscle bundles (left) and fiber orientation (see black arrows) assigned to the main areas (right).

Mentions: One of the key characteristics of the atrial model is the incorporation of realistic fiber orientation based on histological observations [2], [27], [29]–[31]. Our model was divided into 42 areas according to the orientation of the main muscle bundles (circular, longitudinal, transverse or oblique) in order to assign a realistic fiber direction to each region. In Figure 2, the main areas of the model and their fiber orientation can be seen. It shows circulating muscle bundles [2], [27], [31] around the CS and orifices of the pulmonary veins (PV), the SCV and ICV, the AVR, and both appendages (LAPG and RAPG). Fibers of BB, CT and PM have a longitudinal orientation. The free walls of both atria (RA and LA) are smooth and primarily have vertical fibers. The right free wall includes the CT, a fibrous bundle that runs vertically between both caval veins. The fibers between the superior and inferior PV are horizontally positioned, whereas the ostium of the PV contains a complex arrangement of vertical, horizontal and circular fibers [30]. This model is an improved version of the atrial models previously developed by our group [32]–[34].


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)

Fiber orientation in the model.Frontal (A) and dorsal (B) views of the model. The model was divided into 42 areas (represented with different colors) according to the orientation of the muscle bundles (left) and fiber orientation (see black arrows) assigned to the main areas (right).
© Copyright Policy
Related In: Results  -  Collection

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

pone-0050883-g002: Fiber orientation in the model.Frontal (A) and dorsal (B) views of the model. The model was divided into 42 areas (represented with different colors) according to the orientation of the muscle bundles (left) and fiber orientation (see black arrows) assigned to the main areas (right).
Mentions: One of the key characteristics of the atrial model is the incorporation of realistic fiber orientation based on histological observations [2], [27], [29]–[31]. Our model was divided into 42 areas according to the orientation of the main muscle bundles (circular, longitudinal, transverse or oblique) in order to assign a realistic fiber direction to each region. In Figure 2, the main areas of the model and their fiber orientation can be seen. It shows circulating muscle bundles [2], [27], [31] around the CS and orifices of the pulmonary veins (PV), the SCV and ICV, the AVR, and both appendages (LAPG and RAPG). Fibers of BB, CT and PM have a longitudinal orientation. The free walls of both atria (RA and LA) are smooth and primarily have vertical fibers. The right free wall includes the CT, a fibrous bundle that runs vertically between both caval veins. The fibers between the superior and inferior PV are horizontally positioned, whereas the ostium of the PV contains a complex arrangement of vertical, horizontal and circular fibers [30]. This model is an improved version of the atrial models previously developed by our group [32]–[34].

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