ventricular fibrillation is the cause of the most sudden deaths. the recent findings have clearly proved the correlation between the slope of restitution curve with ventricular fibrillation. cellular automata is a powerful tool for simulating complex phenomena in a simple language. in this paper, a simple model is proposed for the simulation of the property of restitution in a single cardiac ce...

Pre-existing heterogeneities present in cardiac tissue are essential for maintaining the normal electrical and mechanical functions of the heart. Exacerbation of such heterogeneities or the emergence of dynamic factors can produce repolarization alternans, which are beat-to-beat alternations in the action potential time course. Traditionally, this was explained by restitution, but additional fa...

OBJECTIVES This study was aimed at evaluating global characteristics of electrical restitution in the human ventricle using noncontact mapping. BACKGROUND Steep action potential restitution (slope >1) and conduction velocity (CV) restitution have been linked with propensity to ventricular fibrillation, but clinical measurement of global electrical restitution had not been feasible. METHODS ...

Aims The steepness of the action potential duration (APD) restitution curve and local tissue refractoriness are both thought to play important roles in arrhythmogenesis. Despite this, there has been little recognition of the apparent association between steady-state APD and the slope of the restitution curve. The objective of this study was to test the hypothesis that restitution slope is deter...

Action potential duration (APD) restitution properties and repolarization alternans are thought to be important arrhythmogenic factors. We investigated the role of intracellular calcium (Ca2+i) cycling in regulating APD restitution slope and repolarization (APD) alternans in patch-clamped rabbit ventricular myocytes at 34 to 36 degrees C, using the perforated or ruptured patch clamp techniques ...

Construction of the action potential duration (APD) restitution portrait allows visualization of multiple aspects of the dynamics of periodically paced myocytes at various basic cycle lengths (BCLs). For the first time, we obtained the restitution portrait of isolated rabbit and guinea pig cardiac ventricular myocytes and analyzed the time constant, tau, of APD accommodation and the slopes of d...

The onset of ventricular fibrillation (VF) has been associated with steep action potential duration restitution in both clinical and computational studies. Recently, detailed clinical restitution properties in cardiac patients were reported showing a substantial degree of heterogeneity in restitution slopes at the epicardium of the ventricles. The aim of the present study was to investigate the...

We study numerically the dynamics of spiral waves in an excitable medium with negative restitution. For our study we use two models of the excitable medium: a cellular automaton and a reaction-diffusion model. There are no significant effects of negative restitution as long as the slope of the restitution curve is less steep than -1. In media with slopes steeper than -1, the dynamics of spiral ...

BACKGROUND We tested the hypothesis that action potential duration (APD) restitution of normal ventricular muscle cells is different during double premature stimuli (S3) compared with a single premature stimulus (S2). We propose a possible ionic mechanism for such a difference. METHODS AND RESULTS Action potentials and isometric tension were recorded simultaneously from isolated canine right ...

BACKGROUND An action potential duration (APD) restitution curve with a steep slope ≥1 has been associated with increased susceptibility for malignant ventricular arrhythmias. We aimed to evaluate the "restitution hypothesis" and tested ventricular APD restitution slope as well as effective refractory period (ERP)/APD ratio for long-term prognostic value in patients with ischemic (ICM) or dilate...