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.
Effect of noise on T-wave alternans measurement in ambulatory ECGs using modified moving average versus spectral method.
Pacing Clin Electrophysiol. 2009 May;32(5):632-41
Europace. 2009 Mar;11(3):374-5
J Cardiovasc Electrophysiol. 2009 Jan;20(1):110-2
Heart Rhythm. 2008 Jul;5(7):1029-35
J Cardiovasc Electrophysiol. 2008 Nov;19(11):1219
Cardiac myocyte transplantation does not increase global epicardial repolarization heterogeneity in a rat infarct model.
J Heart Lung Transplant. 2007 Jun;26(6):630-6
Ventricular fibrillation in myopathic human hearts: mechanistic insights from in vivo global endocardial and epicardial mapping.
Am J Physiol Heart Circ Physiol. 2007 Jun;292(6):H2589-97
Endocardial and epicardial repolarization alternans in human cardiomyopathy: evidence for spatiotemporal heterogeneity and correlation with body surface T-wave alternans.
J Am Coll Cardiol. 2007 Jan 23;49(3):338-46
Europace. 2007 Jan;9(1):10-9
Utility of microvolt T-wave alternans to predict sudden cardiac death in patients with cardiomyopathy.
Curr Opin Cardiol. 2007 Jan;22(1):25-32
Scientist, Toronto General Hospital Research Institute (TGHRI)
Associate Professor, Department of Physiology, University of Toronto