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- Sinus rhythm
- Left axis deviation
- PR - Short (~100-110ms)
- QRS - Prolonged (140ms)
- QT - 400ms (QTc Bazette 380-400 ms)
- ST Elevation leads III, aVF
- ST Depression leads aVL, V5-6 (subtle)
- Delta waves
- Negative delta wave leads III, aVF
- 'Pseudo-infarction' pattern
- Secondary to pre-excitation rather than prior ischaemia
- Occurs in up to 70% of WPW
- AP location posteroseptal tricuspid annulus / coronary sinus ostium
- Axis abnormality, inferior 'Q' waves secondary to pre-excitation
- ST segment changes are also likely secondary to pre-excitation but comparison with old ECG's and serial ECG's are essential if acute ischaemia is suspected.
- Please check out the post, link below, from Dr Smith for examples of pre-excitation with and without acute ischaemia
A must read post
I'd encourage all our readers to look at this post from Dr Smith with some great examples of WPW with and without superimposed ischaemia:
Accessory Pathway Location
There are a number of algorithms that can be used to estimate the location of the accessory pathway (AP). Many of these algorithms can be found in smartphone apps, I use EP Mobile which contains the following algorithms:
- Arruda Algorithm
- Milstein Algorithm
- Modified Arruda Algorithm
What are you going to tell your patient ?
I've put some links here to various patient information resources for WPW, I have not vetted or reviewed all these links but have chosen those from government / institutional sites.
- Cleveland Clinic - WPW Information
- Better Health Channel (Victoria) - WPW Information
- Medline Plus - WPW Information
Life in the Fast Lane
- Chan TC, Brady WJ, Harrigan RA, Ornato JP, Rosen P. ECG in Emergency Medicine and Acute Care. Elsevier Mosby 2005.