PROLONGATION OF THE QT-INTERVAL DURING INDUCTION OF ANESTHESIA IN PATIENTS WITH CORONARY-ARTERY DISEASE

During induction of anesthesia in 60 patients undergoing coronary arte ry bypass grafting (CABG), we measured the QT-interval (QTI) in the EC G, heart rate (HR) and mean arterial pressure (MAP). Based on the HR, we corrected the QT-interval (QTcI). Prior to induction, six patients( 10%) already had abnormal prolongation of QTcI (greater than or equal to 440 ms). After injection of fentanyl and vecuronium, the QTcI incre ased significantly (P < 0.01); to a far lesser extent after injection of hypnotics (i.e. etomidate, midazolam or propofol). Orotracheal intu bation caused significant shortening of QTcI (P < 0.01). HR decreased markedly after injection of fentanyl. MAP decreased, however, only aft er injection of hypnotics. In the immediate post intubation period, HR and MAP increased significantly. The various hypnotics produced no si gnificant difference in HR and QTcI at any measurement point. MAP chan ged only after injection of hypnotics. The decrease of HR and MAP duri ng induction of anesthesia is thought to result from a corresponding r eduction of adrenosympathetic stimulation. We believe that QTcI is sim ilarly influenced.