Related Experiment Videos
Spatial and temporal organization during cardiac fibrillation
R A Gray1, A M Pertsov, J Jalife
1Department of Pharmacology, SUNY Health Science Center, Syracuse, New York 13210, USA. rag@crml.uab.edu
Insights
Cardiac fibrillation, a leading cause of death, shows surprising organization. New methods reveal phase singularities as the sources of this complex cardiac electrical activity.
Area of Science:
- Cardiology
- Biophysics
- Computational Biology
Background:
- Cardiac fibrillation is a major cause of mortality, but its underlying mechanisms remain poorly understood.
- The debate continues on whether fibrillation is a random event or exhibits deterministic patterns, possibly due to rotating electrical waves.
Purpose of the Study:
- To develop a novel algorithm for simplifying the analysis of complex spatiotemporal patterns in cardiac fibrillation.
- To identify the organizing principles and sources of cardiac fibrillation using advanced imaging and data analysis.
Main Methods:
- Utilized potentiometric dye and video imaging to record transmembrane potential dynamics across multiple cardiac sites.
- Developed a new algorithm to reduce data requirements for depicting fibrillation patterns.
- Analyzed transmembrane signals for periodic components and represented cardiac sites by their phase around a 2D-phase space attractor.
Main Results:
- Identified a strong periodic component (around 8 Hz) in transmembrane signals at each site.
- Spatial phase maps revealed topological defects, or phase singularities, as the 'sources' of fibrillation.
- Demonstrated that locating phase singularities elucidates fibrillation formation, termination, and overall organization.
Conclusions:
- Cardiac fibrillation exhibits significant temporal and spatial organization, challenging the notion of it being a purely random phenomenon.
- Phase singularities are key organizing centers in cardiac fibrillation.
- The new algorithm provides an unprecedented method for representing and understanding cardiac fibrillation dynamics.
Abstract:
Cardiac fibrillation (spontaneous, asynchronous contractions of cardiac muscle fibres) is the leading cause of death in the industrialized world, yet it is not clear how it occurs. It has been debated whether or not fibrillation is a random phenomenon. There is some determinism during fibrillation, perhaps resulting from rotating waves of electrical activity. Here we present a new algorithm that markedly reduces the amount of data required to depict the complex spatiotemporal patterns of fibrillation. We use a potentiometric dye and video imaging to record the dynamics of transmembrane potentials at many sites during fibrillation. Transmembrane signals at each site exhibit a strong periodic component centred near 8 Hz. This periodicity is seen as an attractor in two-dimensional-phase space and each site can be represented by its phase around the attractor. Spatial phase maps at each instant reveal the 'sources' of fibrillation in the form of topological defects, or phase singularities, at a few sites. Using our method of identifying phase singularities, we can elucidate the mechanisms for the formation and termination of these singularities, and represent an episode of fibrillation by locating singularities. Our results indicate an unprecedented amount of temporal and spatial organization during cardiac fibrillation.