T-Wave Alternans Testing for Ventricular Arrhythmias

Non-Linear Dynamics of Cardiac Alternans: Subcellular to Tissue-Level Mechanisms of Arrhythmia

“…SCD most commonly occurs as a result of reentrant tachyarrhythmias (ventricular tachycardia (VT) and ventricular fibrillation (VF); Zipes and Jalife, 2004 ), but reliable identification of those patients at highest risk for these events has proven a difficult clinical challenge. Recently, an electrocardiogram (ECG) abnormality, “T-wave alternans” (TWA), has been identified as a sensitive indicator of risk for SCD, thereby becoming the focus of considerable clinical and basic science research (Walker and Rosenbaum, 2003 ; Narayan, 2008 ).…”

“…T-wave alternans is defined as a beat-to-beat alternation in the shape, amplitude, or timing of the T-wave on the ECG, indicative of an underlying alternation in ventricular repolarization (Figure 1 ; Narayan, 2008 ). TWA has been associated clinically (Rosenbaum et al., 1994 ; Narayan, 2008 ; Narayan et al, 2011 ) and experimentally (Chinushi et al, 1998 , 2003 ; Pastore et al, 1999 ; Shimizu and Antzelevitch, 1999 ) with the onset of potentially fatal arrhythmias (VT/VF) in a broad range of clinical contexts, and is now established as a sensitive marker of risk for SCD. TWA testing may be useful in risk stratification for prophylactic implantable cardioverter-defibrillator (ICD) use (Narayan, 2008 ).…”

“…TWA has been associated clinically (Rosenbaum et al., 1994 ; Narayan, 2008 ; Narayan et al, 2011 ) and experimentally (Chinushi et al, 1998 , 2003 ; Pastore et al, 1999 ; Shimizu and Antzelevitch, 1999 ) with the onset of potentially fatal arrhythmias (VT/VF) in a broad range of clinical contexts, and is now established as a sensitive marker of risk for SCD. TWA testing may be useful in risk stratification for prophylactic implantable cardioverter-defibrillator (ICD) use (Narayan, 2008 ). The clinical utility of TWA is the subject of ongoing clinical research, however, and may be limited in part by methodological difficulties (see Nieminen and Verrier, 2010 ; Verrier et al, 2011 , for example).…”

A T-wave Variation Characteristics Evaluation Algorithm for Ischemic Heart Beats

“…Relative QT dispersion value becomes higher when dataset with smaller averaged QT interval, and more difference between the maximum and minimum of QT interval. Relative QT interval is calculated as shown in equation (1).…”

Electrophysiological Mechanisms Underlying T-Wave Alternans and Their Role in Arrhythmogenesis

“…In this manuscript, we present a more comprehensive review associated with underlying mechanisms of TWA and arrhythmogenesis at both cellular and tissue levels revealed through experimental and simulation studies (the mechanism of TWA have also been reviewed: Surawicz and Fisch (1992) , Armoundas and Cohen (1997) , Armoundas et al (2002) , Walker and Rosenbaum (2003) , Narayan (2006 , 2008) , Weiss et al (2006) , Wilson and Rosenbaum (2007) , Merchant et al (2013) , Qu et al (2013) , Disertori et al (2016) , Colman (2020) . One of the most well-known hypotheses for the generation of APD alternans is the APD restitution theory, which was initially established by Nolasco and Dahlen (1968) attributing the generation and persistence of cardiac alternans to the maximum slope of the APD restitution curve.…”