EFFECT OF ATROPINE ON THE QT INTERVAL AND T-WAVE AMPLITUDE IN HEALTHY-VOLUNTEERS

Prolongation of the OT interval of the ECG represents an imbalance in cardiac autonomic function and may predict cardiac arrhythmia. Vagal a ctivity protects against prolongation of the OT interval which may be associated with flattening of the T-wave of the ECG. The changes in QT interval T-wave amplitude and respiratory sinus arrhythmia (RSA) were studied after iv. administration of atropine 20 mug kg-1 or placebo t o 10 healthy volunteers in a cross-over study. After atropine, a decre ase in RSA occurred in all volunteers, but remained at baseline values after placebo. Corrected OT interval (QTc) increased from 410 (20) ms to 454 (11) ms (P < 0.001) 5 min after atropine and remained prolonge d for the entire study period (60 min). The T-wave flattened significa ntly (measured as R:T ratio) up to 30 min, without any changes in the R-wave. No changes in the ECG occurred with placebo.