Premium
Effects of Practolol and Metoprolol on QT Interval, Heart Rate and Arterial Pressure during Induction of Anaesthesia
Author(s) -
Saarnivaara L.,
Lindgren L.,
Hynynen M.
Publication year - 1984
Publication title -
acta anaesthesiologica scandinavica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.738
H-Index - 107
eISSN - 1399-6576
pISSN - 0001-5172
DOI - 10.1111/j.1399-6576.1984.tb02137.x
Subject(s) - practolol , metoprolol , medicine , qt interval , heart rate , anesthesia , blood pressure , intubation , cardiology , propranolol
The effects of the selective β 1 ‐adrenergic receptor blocking agents, practolol with intrinsic sympathetic activity (ISA) and metoprolol without ISA, were studied on QT interval, heart rate, arterial pressure and cardiac arrhythmias during the induction of anaesthesia in 142 adults. In the control group, the QT interval was statistically significantly prolonged after thiopental, and the most marked prolongation occurred after suxamethonium. Neither practolol nor metoprolol alone affected the QT interval. Practolol 100 μg/kg i.v., but not 40 or 150 μg/kg i.v., almost completely reduced the prolongation of the QT interval after suxamethonium. In all doses of 20, 30 and 40 μg/kg i.v. metoprolol statistically significantly and dose‐dependently reduced the prolongation of the QT interval after thiopental, suxamethonium and laryngoscopy, but the prolongation of the QT interval after intubation still occurred. Practolol and metoprolol alone statistically significantly reduced heart rate, but did not prevent the increase of heart rate after thiopental. The effects on arterial pressure were minimal. Neither practolol nor metoprolol prevented the cardiovascular intubation response. Ventricular ectopic beats after intubation occurred in 20% of the patients in the control group and their incidence ranged from 20 to 27% in the groups pretreated with practolol or metoprolol 20 μg/kg. In the groups pretreated with metoprolol 30 or 40 μg/kg, ventricular ectopic beats occurred in 5% and 8%, respectively. It is concluded that the selective β 1 ‐adrenergic receptor blocking agents practolol with ISA, and especially metoprolol without ISA, reduced the prolongation of the QT interval after suxamethonium. The results suggest that the prolongation of the QT interval after suxamethonium may be mediated by the stimulation of the sympathetic nervous system caused by suxamethonium.