Short-term cardiac memory and mother rotor fibrillation.
Short-term cardiac memory refers to the effects of pacing history on action potential duration (APD). Although the ionic mechanisms for short-term memory occurring over many heartbeats (also called APD accommodation) are poorly understood, they may have important effects on reentry and fibrillation. To explore this issue, we incorporated a generic memory current into the Phase I Luo and Rudy action potential model, which lacks short-term memory. The properties of this current were matched to simulate quantitatively human ventricular monophasic action potential accommodation. We show that, theoretically, short-term memory can resolve the paradox of how mother rotor fibrillation is initiated in heterogeneous tissue by physiological pacing. In simulated heterogeneous two-dimensional tissue and three-dimensional ventricles containing an inward rectifier K(+) current gradient, short-term memory could spontaneously convert multiple wavelet fibrillation to mother rotor fibrillation or to a mixture of both fibrillation types. This was due to progressive acceleration and stabilization of rotors as accumulation of memory shortened APD and flattened APD restitution slope nonuniformly throughout the tissue.
Baher
Ali
A
David Geffen School of Medicine at UCLA, Division of Cardiology, 47-123 CHS, 10833 LeConte Ave., Los Angeles, CA 90095-1679, USA. jweiss@mednet.ucla.edu
Qu
Zhilin
Z
Hayatdavoudi
Ashkan
A
Lamp
Scott T
ST
Yang
Ming-Jim
MJ
Xie
Fagen
F
Turner
Stephen
S
Garfinkel
Alan
A
Weiss
James N
JN
D000200:Action Potentials; D000222:Adaptation, Physiological; D000818:Animals; D003198:Computer Simulation; D006329:Heart Conduction System / Q000503:physiopathology*; D008955:Models, Cardiovascular; D011817:Rabbits; D014693:Ventricular Fibrillation / Q000503:physiopathology*