BACKGROUND The restitution of the action potential duration (APDR) and conduction velocity (CVR) are mechanisms whereby cardiac excitation and repolarization adapt to changes in heart rate. They modulate the vulnerability to dangerous arrhythmia, but the mechanistic link between restitution and arrhythmogenesis remains only partially understood. METHODS This paper provides an experimental and...

Spatially discordant alternans (DA) of action potential durations (APD) is thought to be more pro-arrhythmic than concordant alternans. Super normal conduction (SNC) has been reported to suppress formation of DA. An increase in conduction velocity (CV) as activation rate increases, i.e., a negative CV restitution, is widely considered as hallmark of SNC. Our aim in this study is to show that it...

We extend a non-Tikhonov asymptotic embedding, proposed earlier, for calculation of conduction velocity restitution curves in ionic models of cardiac excitability. Conduction velocity restitution is the simplest non-trivial spatially extended problem in excitable media, and in the case of cardiac tissue it is an important tool for prediction of cardiac arrhythmias and fibrillation. An idealized...

Recent experimental results regarding the action potential duration restitution curve have explained the transition from ventricular tachycardia (VT) to fibrillation (VF) in terms of spiral wave (SW) meandering and breakup. However, it remains unclear whether VF always has a steep restitution curve. The present study was designed to test the hypothesis that afterdepolarizations occur at excitab...

The mechanism by which rapid pacing induces ventricular fibrillation (VF) is unclear. We performed computerized epicardial mapping studies in 10 dogs, using 19-beat pacing trains. The pacing interval (PI) of the first train was 300 ms and then was progressively shortened until VF was induced. For each PI, we constructed restitution curves for the effective refractory period (ERP). When the PI w...

Rao JN, Rathor N, Zou T, Liu L, Xiao L, Yu T, Cui Y, Wang JY. STIM1 translocation to the plasma membrane enhances intestinal epithelial restitution by inducing TRPC1-mediated Ca signaling after wounding. Am J Physiol Cell Physiol 299: C579–C588, 2010. First published July 14, 2010; doi:10.1152/ajpcell.00066.2010.—Early epithelial restitution is an important repair modality in the gut mucosa and...

We measure kinematic coefficients of normal restitution in head-on collisions of two identical small spheres of acrylic, ceramic or steel suspended by thin resilient strands at low enough impact speeds for adhesion to lower the restitution. We observe such reduction at speeds consistent with an apparent adhesion surface energy larger than expected.

Combined experimental and theoretical developments have demonstrated that in addition to preexisting electrophysiological heterogeneities, cardiac electrical restitution properties contribute to breakup of reentrant wavefronts during cardiac fibrillation. Developing therapies that favorably alter electrical restitution properties have promise as a new paradigm for preventing fibrillation.

We present numerical simulations of surface waves in vibrated granular systems. For the simulations we use an event driven (ED) procedure with a non-constant restitution coeecient. The important advantage of a non-constant restitution coeecient is that it allows to circumvent the \inelastic collapse", i.e. the divergence of collision frequency, usually observed in ED simulations of dense and di...