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ECGs in the ED.

CASE A 10-year-old boy presents to the emergency department (ED) after complaining of chest pain, shortness of breath, and dizziness while playing on the school playground. He has been otherwise healthy and has never had these symptoms before. The chest pain is described as a squeezing sensation over the left precordium. This preceded the shortness of breath and dizziness. The symptoms occurred while he was running and playing tag. There was no syncope, but he did lose consciousness once before after a field day event. That episode was attributed to dehydration. This episode resolved after approximately 10 minutes of rest. There were no palpitations. There have been no recent fevers or upper respiratory tract symptoms. The teacher noted that the boy appeared pale. The remainder of the medical history is unremarkable. The boy takes no medications and has no known drug allergies. The family history is significant for an uncle who began having heart problems at 35 years of age. The details and diagnosis are not known. The boy attends fifth grade and is very active. There have been no activity limitations. In the ED, the heart rate is 68 beats per minute, and the respiratory rate is 18 breaths per minute. The blood pressure is 106/ 62 mm Hg. The boy is pink and in no distress. He seems to have had complete resolution of any discomfort. The chest is clear to auscultation. The cardiac examination reveals a regular rhythm with an increased precordial impulse. There is a normal first heart sound and physiologically splitting second heart sound. There is no click or gallop. There is a long, harsh III/VI systolic ejection murmur heard at the left sternal border. There is no diastolic murmur. The pulses are full and equal. The abdomen is soft with no hepatomegaly. The extremities are warm and well perfused. An electrocardiogram (ECG) is performed (Fig. 1). ECGs in the ED