Cardinal ECG Features of WPW Syndrome
The cardinal ECG features of WPW syndrome are:
In sinus rhythm
- The ECG may be completely normal or there may be a short PR interval (Fig 1)
- There may be a slurred upstroke of the R wave known as a delta wave
- There may be right (type A) or left (type B) bundle branch block pattern QRS abnormalities (Fig 2)
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| Fig 1: ECG showing WPW | Fig 2: QRS abnormalities in WPW |
During episodes of re-entry tachycardia
- Orthodromic narrow complexes, no delta wave, inverted P waves follow QRS
- Antidromic wide aberrant complexes, no visible P waves