Polymorphic ventricular tachycardia, known as Torsades de Pointes (TdP), is a specific form of ventricular arrhythmia with a characteristic twist of the QRS complex around the isoelectric baseline. TdP can degenerate into ventricular defibrillation followed by sudden cardiac death. A predictor for the development of TdP is the length of the QT interval measured on an EKG recording. The QT interval is known to be prolonged by many medications used in a perioperative setting as well as by other conditions such as hypothermia and electrolyte imbalance. General anesthesia exposes most of the investigators patients to a combination of several of those medications and conditions and therefore might increase the risk for the development of QT prolongation. Moreover, patient related risk factors are well known and aggravate the individual risk for potential life threatening TdP events when exposed to QT prolonging medications perioperatively.