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10 Cards in this Set
- Front
- Back
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What are Kent bundles, James fibers and Mahaim bundles?
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Congenital abnormal connections between the atria and ventricles which bypass the AVN - 'accessory pathways'. The first is the cause of WPW, the others are rare, not easily seen on the ECG and usually found by EPS studies.
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What do the terms orthodromic and antidromic, anterograde and retrograde refer to in WPW?
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Anterograde = conduction down from atria to vent
Retrograde = up from V to A Orthodromic = circus rhythm with anterograde conduction through AVN, retrograde through accessory p-way Antidromic = opposite circus to orthodromic |
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Why do pts with WPW develop sudden cardiac death?
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They are prone to AF, A flutter and circus movement tachycardias. Each of these carries a risk of VF in WPW patients because of a high rate of stimulation of the ventricles (unrestrained by the AVN, which is the normal rate limiting step)
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What are concealed and latent pathways, and what is their effect on the ECG?
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Latent - pathways that are only intermittently conducting. Concealed - pathways that only conduct retrograde. The ECG may be normal or not classical.
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What are the classical ECG findings of WPW?
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PR <0.12 (shortened by intrusion of delta wave)
QRS may widen as it begins with a slurred delta wave - may be positive or negative, and if -ve look like a pathological Q wave! Secondary T wave changes |
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What are type A and B WPW? Which is more common?
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A - bypass tract is on the left side of heart (LA to LV). V1 has a positive QRS. Most common. Q waves inferiorly
B - right side, V1 negative QRS, ST changes inferiorly (pseudoinfarct appearance) |
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What are the potential arrhythmic complications of WPW? ECG findings?
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1) WPW with AF - high risk progression to VF. ECG - irregularly irregular (may look regular if fast), rate often >200, morphology QRS variable (b/c of fusion between AV node and accessory tract conducted beats). May be confused with monomorphic VT
2) WPW with A Flutter - rare. High risk VF. 1:1 AV conduction possible (rates 300) 3) AVRT = WPW SVT = circus rhythm. May be orthodromic or antidromic. Orthodromic - looks like 'normal' SVT (e.g. AVNRT). Can be treated like AVNRT. Most common WPW SVT (80% of circus rhythm) Antidromic - looks like regular WCT e.g VT. V fast rate as high rate of AV conduction, high risk VF. 20% circus rhythm. 3) VF from above mechanisms, note NOT VT (though of course pt may get VT from other causes) |
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WPW AF - which drugs should never be given as treatment? Which are ok? If unstable what is the Rx
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Dig, CCB, BB, adenosine. Block AVN therefore increase conduction down accessory pathway, high risk for VF. Rx (if stable and not using DC version) with Flecainide, amiodarone, sotalol as they also inhibit the accessory pathway.
The preferred treatment, stable or unstable, is DC version. |
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WPW SVT with orthodromic conduction - how does the treatment differ from other SVT (AVRT)?
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It doesn't (e.g. can give adenosine), however be careful to ensure it really is SVT and not AF. Ensure it is regular and be wary of very fast rhythms. May convert to AF with adenosine - if this occurs stop giving adenosine.
Best Rx is still DC cardioversion. |
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Who gets admitted? Who gets EPS?
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Admit - anyone who was treated for WPW tachyarrhythmia for 24 hours monitoring and cardiology rv. All WPW pt get EPS studies; consider referring family members (4x greater risk).
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