A 10-year-old boy with a history of complex congenital heart disease presented to the emergency department for evaluation of a fever. He was recently discharged from the hospital following cardiac surgery. He previously had repair of an atrial septal defect and partial anomalous pulmonary venous return. He had a permanent pacemaker implanted for sinus node dysfunction. He recently had surgery for a pacemaker generator change. He had been recovering uneventfully for the past 2 weeks. The fever started 2 days ago, and has been recurring between doses of ibuprofen. There was some mild redness at the inferior margin of the surgical incision earlier today. He denies sore throat, headache, cough, or rash. He has had a good appetite. There has been no shortness of breath, palpitations, dizziness, or syncope. The past medical history is significant for his cardiac history and seasonal allergies. His only medications are acetaminophen and ibuprofen, and he has no known drug allergies. The family history is noncontributory for congenital heart disease, arrhythmia, or sudden death. He attends 5th grade.
In the emergency department, the patient is acyanotic and in no distress. He is afebrile, the heart rate is 82 bpm, respiratory rate is 20 per minute, and blood pressure is 104/52. He has moist mucous membranes. The head and neck exam is unremarkable. The chest is clear to auscultation. The cardiac exam has a mildly hyperdynamic precordial impulse with a regular rhythm. There is a normal first heart sound and a physiologically split second heart sound. There is no gallop. There is a short II/VI mid-frequency systolic ejection murmur at the left sternal border that does not radiate. There is no diastolic murmur. The pulses are full and equal. The abdomen is soft with a liver edge palpable at the right costal margin. The extremities are warm and well-perfused.
An electrocardiogram was performed (Fig. 1).