Dynamics of action potential head-tail interaction during reentry in cardiac tissue: ionic mechanisms.
In a sufficiently short reentry pathway, the excitation wave front (head) propagates into tissue that is partially refractory (tail) from the previous action potential (AP). We incorporate a detailed mathematical model of the ventricular myocyte into a one-dimensional closed pathway to investigate the effects of head-tail interaction and ion accumulation on the dynamics of reentry. The results were the following: 1) a high degree of head-tail interaction produces oscillations in several AP properties; 2) Ca(2+)-transient oscillations are in phase with AP duration oscillations and are often of greater magnitude; 3) as the wave front propagates around the pathway, AP properties undergo periodic spatial oscillations that produce complicated temporal oscillations at a single site; 4) depending on the degree of head-tail interaction, intracellular [Na(+)] accumulation during reentry either stabilizes or destabilizes reentry; and 5) elevated extracellular [K(+)] destabilizes reentry by prolonging the tail of postrepolarization refractoriness.
Hund
T J
TJ
Department of Biomedical Engineering, Case Western Reserve University, Cleveland, Ohio 44106-7207, USA.
Otani
N F
NF
Rudy
Y
Y
D000200:Action Potentials / Q000502:physiology; D001145:Arrhythmias, Cardiac / Q000473:pathology / Q000503:physiopathology*; D005110:Extracellular Space / Q000378:metabolism; D006321:Heart / Q000503:physiopathology*; D006329:Heart Conduction System / Q000503:physiopathology*; D007477:Ions; D008955:Models, Cardiovascular; D009206:Myocardium / Q000378:metabolism / Q000473:pathology; D009991:Oscillometry; D009994:Osmolar Concentration; D011188:Potassium / Q000378:metabolism; D012032:Refractory Period, Electrophysiological / Q000502:physiology*; D013997:Time Factors
D007477:Ions; D011188:Potassium