OBJECTIVES Our aim was to study the relationship between T-wave alternans (TWA) and rate-response (restitution) of repolarization in subjects with and without ventricular systolic dysfunction. BACKGROUND T-wave alternans is a promising predictor of sudden death, yet the mechanisms linking it with human ventricular arrhythmias are unclear. From theoretic considerations, we hypothesized that ab...

The analysis of cardiac electrical restitution (the relationship between an action potential duration and its preceding diastolic interval) has been used to predict arrhythmia liability. However, the procedure to measure restitution is invasive and disrupts normal physiological autonomic balance. Dynamic analysis of sequential beat-to-beat ECG data was used to study restitution under normal sin...

Human ventricular tissue as well as several animal ventricular preparations show a biphasic shape of the action potential duration restitution curve, with a local maximum at low diastolic intervals. We study numerically how the location and properties of this nonmonotonicity affect the stability of spiral waves. We find that, depending on the slopes of the ascending and of the descending parts ...

Brugada syndrome is a primary electrical disorder of the heart, predisposing affected individuals to potentially lethal, ventricular tachy-arrhythmias. A number of mechanisms have been identified as being important increasing the risk of these rhythms. Wavelength (λ) restitution has been suggested to predict the onset of action potential duration (APD) alternans in mouse Scn5a hearts modelling ...

Periodic sticking motions can occur in vibro-impact systems for certain parameter ranges. When the coefficient of restitution is low (or zero), the range of periodic sticking motions can become large. In this work the dynamics of periodic sticking orbits with both zero and non-zero coefficient of restitution are considered. The dynamics of the periodic orbit is simulated as the forcing frequenc...