Recurrent Syncope in a Child with a Murmur

A 7-year-old male presents to the emergency department with another pre-syncopal event. He had been on the anti-epileptic medication levetiracetam due to two episodes of loss of consciousness over the past month. He describes a prodrome of pallor, diaphoresis, and lightheadedness, and has developed new-onset fatigue and exercise intolerance, enabling him to bike for only about 5-10 minutes. He denies chest pain, palpitations, or edema.

There is a family history of systemic hypertension and dilated cardiomyopathy, but no congenital heart disease or sudden death in childhood.

On physical exam, note is made of a physiologically split S2 with a prominent pulmonary component (P2) and a grade III/IV short, diastolic, high-pitched murmur (Graham Steell murmur) along the left upper sternal border. An electrocardiogram (ECG) (Figure 1), chest X-ray, and transthoracic echocardiogram are obtained.

Figure 1: Electrocardiogram

Figure 1

Figure 2: Chest X-Ray

Figure 2

Figure 3: Transthoracic Echocardiogram Doppler Across the Pulmonary Valve in the Parasternal Short-Axis View

Figure 3

Video 1: Transthoracic Echocardiogram: Parasternal Long-Axis

Video 2: Transthoracic Echocardiogram: Parasternal Short-Axis

Which of the following is the patient's most likely diagnosis?

Show Answer