SVT is the most common sustained arrhythmia of infancy, occurring in 1 in 250-1000 children, and is a serious health burden in Canada and internationally [1, 5-8]. SVT is a common clinical problem facing many health care providers, including general pediatricians, emergency room physicians, nurses, cardiologists, and intensive care physicians. SVT carries significant morbidity and mortality, and patients typically receive long-term medical therapy. Untreated, an infant can tolerate SVT for only a short period before heart failure and shock (or even death) ensues. The management of SVT is currently under debate and often appears to depend on physician preference [9]. While spontaneous termination of the acute episode may occur [1, 2, 6, 9, 10], many infants require medical intervention to terminate the episode. Vagal maneuvres and adenosine have reasonable success in terminating an acute SVT episode, but other medications may also be required. Once the acute episode is treated, the physician(s) must make a decision whether or not to start maintenance (chronic) therapy.