Q. A 3200-g (7 lb) newborn male is delivered at term to a 26-year-old mother. The mother's prenatal care was unremarkable. The mother's history is significant for insulin-controlled gestational diabetes. Upon examination, Apgar scores are 6 at 1 minute and 9 at 5 minutes. General examination shows no specific abnormal facies; however, nasal flaring is noted with a respiratory rate of 75/min. Other vital signs are normal. Cardiac auscultation reveals a continuous murmur best heard over the left infraclavicular region. No additional abnormal heart sound is heard. Chest auscultation shows pulmonary congestion. Laboratory investigations are normal. Echocardiography confirms the suspected diagnosis. Which of the following would be appropriate in the management of this patient's condition?