Multiple atrial thrombi in a neonate presenting with supraventricular tachycardia

Case report A 21-day-old female term neonate presented to a regional hospital in New Zealand with a 2-day history of poor feeding and jaundice. Antenatal period was unremarkable, including no history of fetal tachycardia. At presentation, tachycardia was noted and a 12-lead electrocardiogram confirmed SVT at a rate of 240 beats per minute (Figure 1). Cold water immersions and adenosine boluses of up to 300 mcg/kg produced a transient response; however, SVT persisted. An intravenous amiodarone infusion was started and the baby was air-transferred to our pediatric intensive care unit. The rhythm was still SVT at a rate of 240 beats per minute on arrival; therefore, oral digoxin was added at 5 mcg/kg daily (half standard dose). A focused echocardiogram on arrival demonstrated severe biventricular dysfunction (ejection fraction 23%, fractional shortening 17%). Eight hours after arrival, the rhythm reverted to sinus rhythm. There was no pre-excitation on the 12-lead electrocardiogram (Figure 1). A complete echocardiogram to reassess ventricular function and exclude structural heart disease was performed on day 3 of admission in the pediatric intensive care unit and revealed mobile hyperechoic masses