Cellular consequences of HERG mutations in the long QT syndrome: precursors to sudden cardiac death (IKr629D Mutant Midmyocardial Cell)

Cellular consequences of HERG mutations in the long QT syndrome: precursors to sudden cardiac death

Model Status

This CellML model represents the IKrN629D mutant M cell. FFor more details on the curation status of this model please see this separate notes document.

Model Structure

ABSTRACT: BACKGROUND: A variety of mutations in HERG, the major subunit of the rapidly activating component of the cardiac delayed rectifier I(Kr), have been found to underlie the congenital Long-QT syndrome, LQT2. LQT2 may give rise to severe arrhythmogenic phenotypes leading to sudden cardiac death. OBJECTIVE: We attempt to elucidate the mechanisms by which heterogeneous LQT2 genotypes can lead to prolongation of the action potential duration (APD) and consequently the QT interval on the ECG. METHODS: We develop Markovian models of wild-type (WT) and mutant I(Kr) channels and incorporate these models into a comprehensive model of the cardiac ventricular cell. RESULTS: Using this virtual transgenic cell model, we describe the effects of HERG mutations on the cardiac ventricular action potential (AP) and provide insight into the mechanism by which each defect results in a net loss of repolarizing current and prolongation of APD. CONCLUSIONS: This study demonstrates which mutations can prolong APD sufficiently to generate early afterdepolarizations (EADs), which may trigger life-threatening arrhythmias. The severity of the phenotype is shown to depend on the specific kinetic changes and how they affect I(Kr) during the time course of the action potential. Clarifying how defects in HERG can lead to impaired cellular electrophysiology can improve our understanding of the link between channel structure and cellular function.

The original paper reference is cited below:

Cellular consequences of HERG mutations in the long QT syndrome: precursors to sudden cardiac death, Colleen E. Clancy and Yoram Rudy, 2001, Cardiovascular Research, 50, 301-313. PubMed ID: 11334834

A schematic diagram describing the current flows across the cell membrane that are captured in the Clancy-Rudy model.