UMEM Educational Pearls

Category: Cardiology

Title: tachydysrhythmias and WPW

Keywords: SVT, atrial fibrillation, WPW, antidromic, orthodromic (PubMed Search)

Posted: 8/29/2010 by Amal Mattu, MD (Updated: 7/4/2022)
Click here to contact Amal Mattu, MD

Some confusion exists regarding proper distinction and treatment between the different tachydysrhythmias associated with WPW. Here's the scoop:
1. orthodromic SVT: narrow regular tachycardia, looks just like a routine SVT, treat just like any other SVT (AV nodal blockers work fine)
2. antidromic SVT: wide regular tachycardia, looks just like VTach, treat like VTach (amiodarone, procainamide, shock; lidocaine won't work, though won't harm either)
3. atrial fibrillation: very different!! irregularly irregular, morphologies of the QRS complexes vary between narrow and wide, some areas may have rates as high as 250-300/min, MUST avoid all AV nodal blockers (which includes adenosine, CCBs, BBs, digoxin, amiodarone); treat with procainamide or sedation+cardioversion