title: Transmembrane potential properties of atrial cells at different sites of a spiral wave reentry: cellular evidence for an excitable but nonexcited core.
abstract: Transmembrane action potentials (TAPs) were recorded during simultaneous mapping of a reentrant wavefront induced in canine isolated atria. The activation pattern was visualized dynamically using a high resolution electrode catheter mapping system. During functional reentry (spiral wave), cells in the core of the spiral wave remained quiescent near their resting membrane potential. Cells away from the core progressively gained TAP amplitude and duration, and at the periphery of the spiral wave the cells generated TAPs with full height and duration. During anatomical reentry, when the tip of the wavefront remained attached to the obstacle (a condition of high source-to-sink ratio), the TAP near the obstacle had normal amplitude and duration. However, when the tip of the wavefront detached from the obstacle (condition of lowered source-to-sink ratio) the TAP lost amplitude and duration. These results are consistent with the theory that the source-to-sink ratio determines the safety factor for wave propagation and wave block near the core. With decreasing source-to-sink ratio, TAP progressively decreases in amplitude and duration. In the center of the core, the cells, while excitable, remain quiescent near their resting potential. This decrease reflects a progressive decrease in the source-to-sink ratio. TAP vanishes in the core where cells remain quiescent near their resting potential. Functional and meandering reentrant wavefronts are compatible with the spiral mechanism of reentry where block at the rotating point is provided by the steep curvature of the wave tip.
authors.affiliation: Cedars-Sinai Medical Center, Department of Medicine, UCLA School Medicine 90048, USA. karagueuzian@csmc.edu
authors.forename: H S
authors.initials: HS
authors.lastname: Karagueuzian
authors.forename: C A
authors.initials: CA
authors.lastname: Athill
authors.forename: M
authors.initials: M
authors.lastname: Yashima
authors.forename: T
authors.initials: T
authors.lastname: Ikeda
authors.forename: T J
authors.initials: TJ
authors.lastname: Wu
authors.forename: W J
authors.initials: WJ
authors.lastname: Mandel
authors.forename: P S
authors.initials: PS
authors.lastname: Chen
mesh_terms: D000818:Animals; D001281:Atrial Fibrillation / Q000503:physiopathology; D016275:Atrial Function / Q000502:physiology*; D004285:Dogs; D004594:Electrophysiology; D005260:Female; D006325:Heart Atria / Q000166:cytology; D006329:Heart Conduction System / Q000502:physiology*; D008297:Male; D008564:Membrane Potentials / Q000502:physiology