Key result
A new computational model of human Purkinje fibre cells reproduces distinct electrophysiological characteristics and predicts severe arrhythmogenic activity in long QT syndrome 3.
A novel computational model of Purkinje fibre cells predicts severe arrhythmogenic susceptibility specifically in long QT syndrome 3.
Highlights possible Purkinje contributions to LQT3 arrhythmogenesis; leaves open clinical translation pending validation.
Computer modelling has emerged as a particularly useful tool in understanding the physiology and pathophysiology of cardiac tissues. Models of ventricular, atrial and nodal tissue have evolved and include detailed ion channel kinetics and intercellular Ca(2+) handling. Purkinje fibre cells play a central role in the electrophysiology of the heart and in the genesis of cardiac arrhythmias. In this study, a new computational model has been constructed that incorporates the major membrane currents that have been isolated in recent experiments using Purkinje fibre cells. The model, which integrates mathematical models of human ion channels based on detailed biophysical studies of their kinetic and voltage-dependent properties, recapitulates distinct electrophysiological characteristics unique to Purkinje fibre cells compared to neighbouring ventricular myocytes. These characteristics include automaticity, hyperpolarized voltage range of the action potential plateau potential, and prolonged action potential duration. Simulations of selective ion channel blockade reproduce responses to pharmacological challenges characteristic of isolated Purkinje fibres in vitro, and importantly, the model predicts that Purkinje fibre cells are prone to severe arrhythmogenic activity in patients harbouring long QT syndrome 3 but much less so for other common forms of long QT. This new Purkinje cellular model can be a useful tool to study tissue-specific drug interactions and the effects of disease-related ion channel dysfunction on the cardiac conduction system.
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Sampson et al. (2010) studied Long QT syndrome. Computational model of Purkinje fibre single cell electrophysiology was evaluated on Electrophysiological characteristics and arrhythmogenic activity. A new computational model of human Purkinje fibre cells reproduces distinct electrophysiological characteristics and predicts severe arrhythmogenic activity in long QT syndrome 3.