Ventricular tachyarrhythmias are an important mode of sudden death in patients with cardiomyopathy. Animal studies suggest that abnormal ventricular repolarization can lead to ventricular arrhythmias. In humans, the relevance of cardiac repolarization as a substrate for arrhythmogenesis is not well understood. Our laboratory is characterizing the spatiotemporal distribution of ventricular repolarization in patients with cardiomyopathy and defining the dynamic range of repolarization in response to physiologic stress that can trigger ventricular arrhythmias. The experiments involve body surface and intracardiac recordings of repolarization under varying physiological conditions. Using linear and nonlinear dynamics, several aspects of cardiac repolarization are quantified including spatiotemporal heterogeneity, restitution, memory and alternans. The knowledge gained from our experiments will provide better understanding of the pathogenesis of lethal ventricular arrhythmias in cardiomyopathic patients which may lead to the development of novel antiarrhythmic therapies.
Latent microvolt T-wave alternans in survivors of unexplained cardiac arrest unmasked by epinephrine challenge.
Heart Rhythm. 2012 Jul;9(7):1076-82
Evolving electroanatomic substrate and intra-atrial reentrant tachycardia late after Fontan surgery.
J Cardiovasc Electrophysiol. 2012 Apr;23(4):339-45
Role of KATP channels in the maintenance of ventricular fibrillation in cardiomyopathic human hearts.
Circ Res. 2011 Nov 11;109(11):1309-18
Syncope triggered by a premature ventricular complex: a case of atrial fibrillation and paroxysmal atrioventricular block.
Heart Rhythm. 2012 Oct;9(10):1650-1
Trafficking defect and proteasomal degradation contribute to the phenotype of a novel KCNH2 long QT syndrome mutation.
PLoS One. 2011;6(3):e18273
Modulated dispersion of activation and repolarization by premature beats in patients with cardiomyopathy at risk of sudden death.
Am J Physiol Heart Circ Physiol. 2011 Jun;300(6):H2221-9
T wave alternans evaluation using adaptive time-frequency signal analysis and non-negative matrix factorization.
Med Eng Phys. 2011 Jul;33(6):700-11
Outcome of intra-atrial re-entrant tachycardia catheter ablation in adults with congenital heart disease: negative impact of age and complex atrial surgery.
J Am Coll Cardiol. 2010 Nov 2;56(19):1589-96
Microscopic systolic pressure alternans in human cardiomyopathy: noninvasive evaluation of a novel risk marker and correlation with microvolt T-wave alternans.
Heart Rhythm. 2011 Feb;8(2):236-43
Pacing Clin Electrophysiol. 2012 Jan;35(1):e1-5
Scientist, Toronto General Hospital Research Institute (TGHRI)
Associate Professor, Department of Physiology, University of Toronto