We read with great interest the article by Dixon et al on the dosing of adenosine in supraventricular tachycardia (SVT).¹ We have recently reviewed cases of SVT presenting to the Children’s Heart Unit of Wales with a special focus on the effective dose of adenosine, and have made disturbingly similar observations. Our findings were recently presented at a research society meeting.

Over a period of 10 years a total of 137 infants and children presented to our unit with a diagnosis of SVT. Of these adenosine was used in 37 cases on 70 occasions. Throughout South Wales the Advanced Paediatric Life Support (APLS) guidelines for adenosine are followed, which suggest incremental doses of 50 μ/kg, 100 μ/kg, and 250 μ/kg for the acute management of SVT.

The recommended starting dose of 50 μ/kg was effective only on four occasions—that is, in less than 6% of the cases. The second dose was effective on another 33 (47%) occasions, while the third dose of 250 μ/kg successfully terminated the arrhythmia in another 24 (34%) cases. Adenosine was ineffective on 9 (13%) occasions. Other agents were required in these cases. The mean effective dose of adenosine thus works out to be 156 μ/kg.

Our findings support the conclusions of Dixon et al that the current recommended adenosine doses for acute management of SVT are ineffective in the vast majority of cases. This highlights the urgent need for review of the dose protocol of adenosine in SVT.