[Terminating supraventricular tachycardia with adenosine--comparing the effectiveness of 12 mg and 18 mg].

OBJECTIVE

This study was done to answer the question if intravenous application of 18 mg adenosine is superior to 12 mg adenosine for the termination of supraventricular tachycardias.

METHODS

31 patients (17 men, 14 women, mean age 53 +/- 15 years [range 15-76 years]) had electrophysiological tests. In 25 patients AV nodal reentrant tachycardias were induced during programmed stimulation, 6 patients had inducible AV reentrant tachycardias with an accessory pathway. After induction of the supraventricular tachycardia (mean rate 183 +/- 29/minute, range 115-240/minute), in each patient 12 or 18 mg adenosine was applied in a bolus for terminating of the tachycardia. After the second induction of the tachycardia, a dose of 18 or 12 mg adenosine was given. The different doses of adenosine were chosen in a randomized and prospective manner in a crossover design.

RESULTS

In 25 of the 31 patients (81%) the tachycardia was terminated by 12 mg adenosine. In 29 of the 31 patients (94%) the induced tachycardia was terminated by the application of 18 mg adenosine (no significant difference). In one patient, the tachycardia cessation was observed after 12 mg adenosine, but not after 18 mg adenosine. In another patient the tachycardia was not terminated by either 12 mg or by 18 mg adenosine. The termination of the tachycardia was seen after 25 +/- 8 seconds (13-51 seconds) when 12 mg adenosine was given. After the application of 18 mg adenosine the tachycardia ended after 25 +/- 8 seconds (14-44 seconds) (not significant). The asystole directly after tachycardia termination was 976 +/- 63 milliseconds (540-1700 milliseconds) with 12 mg adenosine, and 1070 +/- 628 milliseconds (530-4000 milliseconds) after the application of 18 mg adenosine (not significant). The longest asystole after termination of a tachycardia by 18 mg adenosine was 9.03 seconds. In one patient the tachycardia was reinitiated by spontaneous atrial extrasystoles after 12 mg adenosine, and reinduction of tachycardia was seen twice after 18 mg adenosine. After the administration of 18 mg adenosine, atrial fibrillation was observed in one patient. No serious complication occurred.

CONCLUSIONS

In AV nodal reentrant tachycardias and AV reentrant tachycardias with an accessory pathway, which can not be terminated by the administration of adenosine in a dose of 12 mg, the tachycardia can be terminated more effectively by the application of 18 mg adenosine.