[Torsades de pointes and prolongation of the duration of QT interval after injection of droperidol].

Following a case of torsades de pointe (TDP) after the injection of droperidol (D), the authors studied the electrocardiographic variations caused by the drug. Fifty five unselected patients under the same conditions (general anesthesia) were given D (0.25 mg/kg IV). Significant prolongation of the QT interval was seen in 70% of cases by the end of the first minute. QT interval and the ratio of QTm (measured) over QTt increased from 387 +/- 34 ms to 423 +/- 37 ms (p less than 0.0001) and from 1.06 +/- 0.08 to 1.28 +/- 0.1 (p less than 0.001) respectively. These changes could favourise the onset of TDP. Although exceptional in terms of the extensive use of the neuroleptic in question, this possibility indicates the need for monitoring of the duration of QT before and during treatment with droperidol and for prescription of the drug to be avoided in circumstances known to be propitious to this arrhythmia (bradycardia, hypokalemia, anti-arrhythmic drugs).