Routine ECG during sports evaluation in an 8-years old girl revealed the following:
On first sight this ECG seems to be pretty normal. There is one clearly visible short sinus pause, rhythm is sinus at a heart rate of 85bpm. However, there is evidence of intermittent preexcitation, given away by the 3rd beat in the tracing.
Here you see a short PR interval (100ms) and a clear positive Delta-wave inferior (II, III, aVF). This is an intermittent Wolff-Parkinson-White pattern. Since the patient was asymptomatic thus far, you may not call this WPW-syndrome. The WPW-syndrome is diagnosed in the presence of tachycardias and a WPW-pattern in the ECG.
These intermittent preexcitations are easily overlooked and concise ECG evaluation is key if you want to catch such a Wolff.