Dangerous arrhythmia with WPW syndrome – Cardiology MCQ

Dreaded arrhythmia in association with WPW syndrome (Wolff-Parkinson-White syndrome) is:
1. Orthodromic atrioventricular re-entrant tachycardia (Orthodromic AVRT)
2. Antidromic atrioventricular re-entrant tachycardia (Antidromic AVRT)
3. Atrial fibrillation
4. Atrial flutter
Correct answer: 3. Atrial fibrillation
Orthodromic AVRT is the commonest arrhythmia in WPW syndrome, while atrial flutter is not an arrhythmia usually associated with WPW syndrome. In orthodromic AVRT, the signal passes down the normal atrioventricular conduction system and back from the ventricle to the atrium by the accessory pathway. Hence the QRS is narrow. The opposite occurs in antidromic AVRT causing the QRS to be wide.
In atrial fibrillation, the high atrial rates are conducted down simultaneously through both the normal atrioventricular (AV) node as well as through the accessory pathway so that the ventricular rates become very high. Normal AV node has the property of decreasing conduction when it receives large number of atrial signals. But accessory pathway in fact conducts more impulses at faster rates. The dangerously high ventricular rates can degenerate into ventricular fibrillation. Hence atrial fibrillation with WPW syndrome presents as a fast irregular wide QRS tachycardia and needs immediate electrical cardioversion (DC shock) to prevent sudden deterioration.
Though atrial fibrillation in WPW syndrome is life threatening in the absence of immediate treatment, rare case of tachycardiomyo...

Source: Cardiophile MD - November 16, 2015 Category: Cardiology Authors: Prof. Dr. Johnson Francis, MD, DM, FACC, FRCP Edin, FRCP London Tags: Cardiology MCQ DM / DNB Cardiology Entrance atrial fibrillation irregular wide QRS tachycardia Wolff-Parkinson-White syndrome Source Type: blogs