The effect of intravenous bolus doses (0.25. 0.5. 1.0 fig) of isopwterenol on the QT and BR intervals was reviewed in a group of 34 children undergoing autonomic testing for svncope. Twenty‐one patients had a positive orthostatic test and 13 were negative. The two groups (positive and negative) were compared Baseline QT and RR intervals were similar. The RR interval was shortened by isoproterenol in both groups Isoproterenol shortened the QT interval in the negative group (as seen in normal persons), but produced QT prolongation in the positive group, although neither reached statistical significance when compared to baseline within the respective group. Comparing the values for RR and QT at each dose of isoproterenol (including baseline) between the two groups showed a significant difference in the QT interval after the 1.0‐fxg dose of isoproterenol. Thus children with orthostatic positive neurocardiogenic syncope showed a different QT response to fi‐adrenergic stimulation. This lends support to the theory of altered /3‐adrenergic sensitivity being present in children with neurocardiogenic syncope.
|Original language||English (US)|
|Number of pages||5|
|Journal||Pacing and Clinical Electrophysiology|
|State||Published - Feb 1994|
ASJC Scopus subject areas
- Cardiology and Cardiovascular Medicine