[Effect of intravenous infusions of theophylline on cardiac arrhythmias and activity of creatinine kinase CK-MB in patients with airway obstruction]. / Wplyw dozylnych wlewów teofiliny na wystepowanie zaburzen rytmu serca i aktywnosc frakcji sercowej kinazy kreatynowej CK-MB u chorych z obturacja dróg oddechowych.

ABSTRACT

The effect of intravenous theophylline upon the activity of creatinine kinase (CK) and its cardiac specific isoenzyme compound (CK-MB) and the frequency of cardiac arrhythmias was evaluated in 12 patients with bronchial asthma and spastic bronchitis. The patients were receiving an intravenous infusion of theophylline for three days. On the first day twice (400 mg and 300 mg) and subsequently, 400 mg once daily over 30 minutes. 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-h Holter monitoring the electrocardiogram was performed. CK-MB elevation was observed related 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 min after termination of the infusion. The elevation was sustained 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. On the third day of the study, although theophylline had been withheld for 24 hours the baseline CK-MB levels were found to be higher than on day 1, at 14.35 +/- 5.35 (the difference, however, was not statistically significant) and the activity increased after each theophylline infusion (21.7 +/- 6.7 units, 22.5 +/- 5.7 units, 23.6 +/- 5.5 units and 28.2 +/- 7.3 units respectively). No statistically significant differences in CK activity were found. In most patients the heart rate was accelerated during the theophylline infusion and four patients developed clinically silent ventricular arrhythmias obviously related to the infusion. In one patient a five-hour long bout of atrial fibrillation, which resolved spontaneously was observed. No changes were found in the ST-T segment. The ventricular arrhythmias correlated with the increased activity of CK-MB and were related to the serum theophylline levels. The study confirms a potential cardiotoxic effect of intravenous theophylline with a resultant requirement of careful adjustment of doses.