Prolongation of QT Interval in Isolated Feline Hearts by Antipsychotic Drugs

Abstract
Some antipsychotic drugs have been found to prolong the QT interval on electrocardiographic (ECG) recordings, a phenomenon which, when severe, may facilitate the occurrence of complex ventricular arrhythmias such as torsade de pointes.However, the effects of these drugs on the cardiac repolarization process have not been evaluated extensively. This study was designed to examine the potency of five antipsychotic drugs in lengthening the QT interval of the perfused feline heart: haloperidol, risperidone, sertindole, clozapine, and olanzapine. The hearts were infused with increasing concentrations of drugs (0.1-20 [micro sign]mol/L) for 40-minute intervals at each concentration. ECG recordings were made, with signals amplified and data recorded on a strip chart recorder. Four representative beats from each set of three signal recordings were chosen for QT interval measurement. Our data indicated that all tested drugs prolonged the QT interval in a concentration-dependent manner (p