Back to Search
Start Over
Mechanistic insights into very slow conduction in branching cardiac tissue: a model study.
- Source :
-
Circulation research [Circ Res] 2001 Oct 26; Vol. 89 (9), pp. 799-806. - Publication Year :
- 2001
-
Abstract
- It is known that branching strands of cardiac tissue can form a substrate for very slow conduction. The branches slow conduction by acting as current loads drawing depolarizing current from the main strand ("pull" effect). It has been suggested that, upon depolarization of the branches, they become current sources reinjecting current back into the strand, thus enhancing propagation safety ("push" effect). It was the aim of this study to verify this hypothesis and to assess the contribution of the push effect to propagation velocity and safety. Conduction was investigated in strands of Luo-Rudy dynamic model cells that branch from either a single branch point or from multiple successive branch points. In single-branching strands, blocking the push effect by not allowing current to flow retrogradely from the branches into the strand did not significantly increase the branching-induced local propagation delay. However, in multiple branching strands, blocking the push effect resulted in a significant slowing of overall conduction velocity or even in conduction failure. Furthermore, for certain slow velocities, the safety factor for propagation was higher when slow conduction was caused by branching tissue geometry than by reduced excitability without branching. Therefore, these results confirm the proposed "pull and push" mechanism of slow, but nevertheless robust, conduction in branching structures. Slow conduction based on this mechanism could occur in the atrioventricular node, where multiple branching is structurally present. It could also support reentrant excitation in diseased myocardium where the substrate is structurally complex.
- Subjects :
- Animals
Atrioventricular Node physiology
Cardiac Pacing, Artificial
Cells, Cultured
Computer Simulation
Electrophysiologic Techniques, Cardiac
Heart Conduction System cytology
Membrane Potentials physiology
Myocardium cytology
Potassium metabolism
Rats
Reaction Time physiology
Heart physiology
Heart Conduction System physiology
Models, Cardiovascular
Myocardial Contraction physiology
Myocardium metabolism
Subjects
Details
- Language :
- English
- ISSN :
- 1524-4571
- Volume :
- 89
- Issue :
- 9
- Database :
- MEDLINE
- Journal :
- Circulation research
- Publication Type :
- Academic Journal
- Accession number :
- 11679410
- Full Text :
- https://doi.org/10.1161/hh2101.098442