title: Acquired long QT syndrome: Unequal regression of Amiodarone-induced repolarization lengthening.
abstract: We describe full exposure of an acquired Long QT Syndrome (aLQTS) in an elderly female patient on long-term Amiodarone treatment. We propose that the aLQTS is the result of combined block of the rapid (I(Kr)) and delayed (I(Ks)) components of the outward potassium current (I(K)), translated to the ECG in a (more than expected) prolonged QT interval, an augmented transmural dispersion of repolarization (TDR) and an interrupted T wave. The unequal regression of repolarization lengthening made possible to individualize I(K) current components in the inscription of the interrupted T wave, which argues against the U wave as a separate entity. Silent ion channel gene mutations or polymorphisms and downregulation of beta-adrenergic activation of I(Ks) may underlie the unusual repolarization behaviour. The unequal regression over time of Amiodarone-induced repolarization lengthening could have clinical significance.
authors: Tomas
authors: T
authors: Raviña
authors: Paula
authors: P
authors: Raviña
authors: Javier
authors: J
authors: Gutierrez
mesh_terms: D000369:Aged, 80 and over; D000638:Amiodarone / Q000009:adverse effects*; D000889:Anti-Arrhythmia Agents / Q000009:adverse effects*; D004562:Electrocardiography / Q000187:drug effects; D005260:Female; D005500:Follow-Up Studies; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D008133:Long QT Syndrome / Q000139:chemically induced* / Q000503:physiopathology; D012075:Remission, Spontaneous; D013997:Time Factors
chemical_list: D000889:Anti-Arrhythmia Agents; D000638:Amiodarone