Related Experiment Video
Updated: Jul 16, 2026

Electrocardiogram Recordings in Anesthetized Mice using Lead II
Published on: June 20, 2020
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.
Related Concept Videos
Antiarrhythmic Drugs: Class III Agents as Potassium Channel Blockers
Dysrhythmias IV: Characteristics of Bradyarrhythmias
ECG Interpretation of Arrhythmias II: Atrial, Junctional and Ventricular Arrhythmias
Cardiac Action Potential
The cardiac action potential process involves a series of phases characterized by the movement of ions across the cardiac cell membranes, leading to the depolarization and repolarization of the cardiac myocytes.
Ionic Basis of Cardiac Action Potentials
Dysrhythmias II: Classification of Tachyarrhythmias
Mechanism of Cardiac Arrhythmias
