WPW syndrome

A 38-year-old male came with a history of recurrent palpitation since the last 2 years.  ECG at the time of tachycardia was not available. Echocardiography showed a structurally normal heart. Sinus ECG is shown below.

Sinus ECG

Source of the image: Rajiv Gandhi super speciality hospital, Dilshad Garden, New Delhi

ECG  normal sinus rhythm @ 100 beats per minute, normal axis, PR 80 msec, Positive delta wave in lead V1, negative delta wave in II, III, avF. Reciprocal ST-segment depression with T wave inversion is seen in lead II, III, aVF. Also, ST-segment depression with T wave inversion is seen in lead I, avL, V3-V6. Sudden transition is seen in from lead V1 to V2. QT interval  420 msec.

 The ECG is suggestive of Pre-excitation. In view of positive delta wave in  V1 along with sudden transition in lead V2, it is left- posteroseptal pathway. The final diagnosis of the patient is WPW syndrome with left lateral pathway. The patient was referred to AIIMS (New Delhi) for EPS study and pathway ablation.

How to localize pathway in WPW syndrome?

Thank you