Introduction:

Syncope is a frequent motive of concern in pediatrics. Despite its mostly benign etiology, it is fundamental to exclude life-threatening causes.

Case report:

We describe a 12-year-old boy brought to the emergency department because of a first syncopal event that lasted for five minutes with generalized hypertonia. His mother had a history of syncopal episodes who were classified as being epileptic, and there were no other relevant findings on family history. Physical exam and electrocardiogram (ECG) showed no anomalies. He was referred to a neuropediatric consult, where he underwent an electroencephalogram with a normal result. Eighteen months later he experienced another syncopal event that lasted a few seconds. He then repeated an ECG that showed sinus rhythm and a QTc of 511ms, leading to a diagnosis of long QT syndrome. He was referred to both pediatric cardiology and genetics consults, with identification of a genetic mutation, and was started on beta-blocker therapy. After studying his family, both his mother and his sister were confirmed as having the same diagnosis.

Comments:

Long QT syndrome is defined as a disorder of myocardial repolarization, associated with an increased risk of sudden death. Children may range from being asymptomatic to experiencing palpitations, syncope, or even cardiac arrest. Despite its rarity, the diagnosis may be suspected on a regular ECG. The approach of a syncopal event in a child with a previous normal ECG does not exclude the diagnosis, as this electrocardiographic change can be intermittent. A positive family history supports the diagnosis. When the child is the first described case, his relatives should be evaluated.

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