[Drug-induced long QT syndrome. Relevancy in intensive care medicine]

Abstract

QT-prolonging drugs delay ventricular repolarization and, thus, favor the occurrence of Torsade de pointes (TdP). Intensive care patients are particularly endangered to suffer from this clinical picture as they often simultaneously exhibit multiple risk factors. In the following article, the most important risk factors for drug-induced long QT syndrome are described. An overview on how the QT interval can be influenced by various endo- and exogenous factors is provided. In addition, the measurement of this interval and potential sources of errors are described. Electrophysiological characteristics of TdP are delineated as well as important pathophysiological mechanisms of arrhythmogenesis, e.g., transmural dispersion of repolarization; T(peak)-T(end) interval as a marker for that dispersion is described. Potential explanations why prolongation of the QT interval is not the main or only factor for the proarrhythmic potential of QT-prolonging drugs are discussed. Furthermore, a summary of QT-prolonging drugs relevant in intensive care units is given and prevention of drug-induced long QT syndrome with consecutive TdP is discussed. Finally, recommendations for treatment of drug-induced TdP are reviewed.