The Effect of General Anesthesia on the Risk for Arrhythmia

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.

Previous research suggests that more than 20% of the patients might develop QT prolongations
perioperatively and are consequently on an increased risk for TdP; yet, no study has
systematically investigated the magnitude of the problem and associated risk factors.

The proposed pilot study is designed as a prospective observational cohort study to
investigate the QT interval before, during and after general anesthesia. It aims to
determine the incidence of perioperative QT prolongations. A customary long term EKG
recording device will be connected to a random sample of patients undergoing general
anesthesia. Using these continuous EKG tracings, the lengths of the QT interval will be
analyzed during the perioperative period.