Control of electrical alternans in simulations of paced myocardium using extended time-delay autosynchronization

Abstract

Experimental studies have linked alternans, an abnormal beat-to-beat alternation of cardiac action potential duration (APD), to the genesis of lethal arrhythmias such as ventricular fibrillation. Prior studies have considered various closed-loop feedback control algorithms for perturbing interstimulus intervals in such a way that alternans is suppressed. However, some experimental cases are restricted in that the controller's stimuli must preempt those of the existing waves that are propagating in the tissue and therefore only shortening perturbations to the underlying pacing are allowed. We present results demonstrating that a technique known as Extended Time-Delay Autosynchronization (ETDAS) can effectively control alternans locally while operating within the above constraints. We show that ETDAS, which has already been used to control chaos in physical systems, has numerous advantages over previously proposed alternans control schemes.

Restricted feedback control in discrete-time dynamical systems with memory

“…where A max = 392 ms, β = 525 ms, and τ = 40 ms. For this mapping, the bifurcation to alternans occurs when B ≈ 455 ms; for a bifurcation diagram of (9) and (10), see [18]. While one-dimensional restitution models of the form (9) may be appropriate in some settings, A n+1 is influenced not only by A n , but also by a variety of other factors.…”

Effect of Extracellular Calcium Concentration on Controlling Cardiac Alternans

“…Besides the earlier proposed methods for alternans suppression: the proportional feedback control [6,7] and adaptive scheme [8][9][10], a new control scheme, the T+T-feedback control [11][12][13][14] was proposed recently. The basic pacing period T in this method is designed to change between two values, T +  and T - (where  is a predetermined control parameter and is much less than T), repeatedly until the alternans is suppressed.…”

“…It may lead to life-threatening cardiac arrhythmias [3,4], such as ventricular tachycardia and ventricular fibrillation, or sudden cardiac death [4,5] if it is left without any further medical treatment or intervention. Therefore, searching for an effective alternans control method is crucial.Besides the earlier proposed methods for alternans suppression: the proportional feedback control [6,7] and adaptive scheme [8][9][10], a new control scheme, the T+T-feedback control [11][12][13][14] was proposed recently. The basic pacing period T in this method is designed to change between two values, T +  and T - (where  is a predetermined control parameter and is much less than T), repeatedly until the alternans is suppressed.…”

Applications of Control Theory to the Dynamics and Propagation of Cardiac Action Potentials

“…2-7,9-12,19 In most of these studies, alternans was suppressed using appropriately timed electrical stimuli, delivered through electrodes embedded in simulated or real tissue. Other researchers have suggested using alternate methods, such as the application of mechanical stimuli 16 or drug delivery, 17 for reversing unwanted AP patterns.…”