Preexcitation

prexcitation

Preexcitation

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This ECG has a superficial resemblance to left bundle branch with tall slurred QRS complexes in lateral leads. The QS complexes in inferior leads mimic inferior wall infarction. Actually it is a non infarction Q wave or pseudoinfarction pattern. The PR interval is short and is immediately followed by the slurred initial portion of the QRS in lateral leads, which is the positive delta wave. These features are suggestive of ventricular preexcitation as in Wolff–Parkinson–White syndrome (WPW Syndrome). The delta wave is negative in inferior leads and V1. The tall QRS in lateral leads also mimic left ventricular hypertrophy.