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.
Increased ventricular repolarization heterogeneity in patients with ventricular arrhythmia vulnerability and cardiomyopathy: a human in vivo study.
Am J Physiol Heart Circ Physiol. 2006 Jan;290(1):H79-86
Magnetoelectroanatomic mapping of arrhythmias in structural heart disease using a novel multielectrode catheter:.
Pacing Clin Electrophysiol. 2004 Aug;27(8):1077-84
Rapid magnetic electroanatomic mapping of typical atrial flutter using a novel multielectrode catheter.
J Cardiovasc Electrophysiol. 2003 Jun;14(6):673
Unusual intraatrial reentry following the Mustard procedure defined by multisite magnetic electroanatomic mapping.
Pacing Clin Electrophysiol. 2003 Apr;26(4 Pt 1):902-5
Sex differences in QTc interval and QT dispersion: dynamics during exercise and recovery in healthy subjects.
Am Heart J. 2002 Nov;144(5):858-64
Am Heart J. 2002 Mar;143(3):528-34
J Electrocardiol. 2001 Apr;34(2):109-17
Med Clin North Am. 2001 Mar;85(2):193-223, ix
Abnormal cardiac Na(+) channel properties and QT heart rate adaptation in neonatal ankyrin(B) knockout mice.
Circ Res. 2000 Mar 3;86(4):441-7
beta-Adrenergic action on wild-type and KPQ mutant human cardiac Na+ channels: shift in gating but no change in Ca2+:Na+ selectivity.
Cardiovasc Res. 1999 May;42(2):490-502
Scientist, Toronto General Hospital Research Institute (TGHRI)
Associate Professor, Department of Physiology, University of Toronto