Cardiac arrhythmias as a result of intravenous infusions of theophylline in patients with airway obstruction.

The effect of intravenous theophylline upon the activity of creatinine kinase (CK) and its cardiac specific isoenzyme (CK-MB) and the frequency of cardiac arrhythmias were evaluated in 12 patients with bronchial asthma and spastic bronchitis. Measurements of the peak expiratory flow (PEF) were obtained prior to theophylline administration, immediately after the infusion and at 1, 3 and 6 hours, while serum theophylline levels were determined at the same time by enzyme immunoassay. Continuous 24-hour Holter monitoring of the electrocardiogram before the study and at the first day of the investigations was performed. CK-MB elevation was observed relating to the theophylline infusion. The CK-MB activity prior to theophylline administration was 10.87 +/- 5.2 units and 24.9 +/- 13.4 units at 5 minutes after termination of the infusion. The elevation lasted until the end of the observation period, being 29.4 +/- 17 units at 1 hour, 27.95 +/- 12.1 units at 3 hours and 34.9 +/- 13.9 at 6 hours. No statistically significant differences in CK activity were found. In most patients the heart rate was accelerated during the theophylline infusion and 4 patients developed clinically silent ventricular arrhythmias obviously related to the infusion. In one patient a 5-hour long bout of atrial fibrillation, which resolved spontaneously, was observed. No changes were found in the ST-T segment.(ABSTRACT TRUNCATED AT 250 WORDS)