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.
Conf Proc IEEE Eng Med Biol Soc. 2009;2009:39-42
Short-term memory and restitution during ventricular fibrillation in human hearts: an in vivo study.
Circ Arrhythm Electrophysiol. 2009 Oct;2(5):562-70
Adrenergic stimulation increases repolarization dispersion and reduces activation-repolarization coupling along the RV endocardium of patients with cardiomyopathy.
Europace. 2009 Nov;11(11):1529-35
Pacing Clin Electrophysiol. 2009 Dec;32(12):1582-3
Heart Rhythm. 2009 Sep;6(9):1391-4
Clinical considerations for allied professionals: understanding and optimizing three-dimensional electroanatomic mapping of complex arrhythmias--part 1.
Heart Rhythm. 2009 Aug;6(8):1249-52
Body surface projection of action potential duration alternans: a combined clinical-modeling study with implications for improving T-wave alternans detection.
Heart Rhythm. 2009 Aug;6(8):1211-9
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
Scientist, Toronto General Hospital Research Institute (TGHRI)
Associate Professor, Department of Physiology, University of Toronto