title: Modeling of IK1 mutations in human left ventricular myocytes and tissue.
abstract: Elucidation of the cellular basis of arrhythmias in ion channelopathy disorders is complicated by the inherent difficulties in studying human cardiac tissue. Thus we used a computer modeling approach to study the mechanisms of cellular dysfunction induced by mutations in inward rectifier potassium channel (K(ir))2.1 that cause Andersen-Tawil syndrome (ATS). ATS is an autosomal dominant disorder associated with ventricular arrhythmias that uncommonly degenerate into the lethal arrhythmia torsade de pointes. We simulated the cellular and tissue effects of a potent disease-causing mutation D71V K(ir)2.1 with mathematical models of human ventricular myocytes and a bidomain model of transmural conduction. The D71V K(ir)2.1 mutation caused significant action potential duration prolongation in subendocardial, midmyocardial, and subepicardial myocytes but did not significantly increase transmural dispersion of repolarization. Simulations of the D71V mutation at shorter cycle lengths induced stable action potential alternans in midmyocardial, but not subendocardial or subepicardial cells. The action potential alternans was manifested as an abbreviated QRS complex in the transmural ECG, the result of action potential propagation failure in the midmyocardial tissue. In addition, our simulations of D71V mutation recapitulate several key ECG features of ATS, including QT prolongation, T-wave flattening, and QRS widening. Thus our modeling approach faithfully recapitulates several features of ATS and provides a mechanistic explanation for the low frequency of torsade de pointes arrhythmia in ATS.
authors.affiliation: Nora Eccles Harrison Cardiovascular Research and Training Institute, Univ. of Utah, Salt Lake City, UT 84108, USA. fs@cvrti.utah.edu
authors.forename: Gunnar
authors.initials: G
authors.lastname: Seemann
authors.forename: Frank B
authors.initials: FB
authors.lastname: Sachse
authors.forename: Daniel L
authors.initials: DL
authors.lastname: Weiss
authors.forename: Louis J
authors.initials: LJ
authors.lastname: Ptácek
authors.forename: Martin
authors.initials: M
authors.lastname: Tristani-Firouzi
mesh_terms: D000200:Action Potentials; D050030:Andersen Syndrome / Q000503:physiopathology*; D003198:Computer Simulation; D020022:Genetic Predisposition to Disease / Q000235:genetics; D006352:Heart Ventricles / Q000473:pathology / Q000503:physiopathology*; D006801:Humans; D015640:Ion Channel Gating; D008564:Membrane Potentials; D008955:Models, Cardiovascular; D008957:Models, Genetic; D032383:Myocytes, Cardiac; D024661:Potassium Channels, Inwardly Rectifying / Q000235:genetics* / Q000378:metabolism*
chemical_list: C489457:KCNJ2 protein, human; D024661:Potassium Channels, Inwardly Rectifying