USMLE Forums - View Single Post - question_ WPW Syndrome and Verapamil
View Single Post
Old 11-12-2010
ashishkabir's Avatar
ashishkabir ashishkabir is offline
USMLE Forums Master
Steps History: 1+CK+CS+3
Posts: 625
Threads: 19
Thanked 404 Times in 240 Posts
Reputation: 424

What happens in WPW is that there is an alternative (aka accessory) pathway for electrical conduction - not just the AV node. This causes the ventricles to contract more often than they should leading to tachyarrythmias... To treat this, you want to slow down the rhythm or stabilize it some other way until you can find and destroy the accessory pathway using catheter ablation. If you use CCBs in this scenario - you're going to let the conduction from the atria to the ventricle occur in every pathway *except* through the AV node. So, you dont do that....

From wiki:
Acutely, people with WPW who are experiencing tachyarrhythmias may require electrical cardioversion if their condition is critical, or, if more stable, medical treatment may be used.

Patients with atrial fibrillation and rapid ventricular response are often treated with amiodarone.[10] or procainamide[11] to stabilize their heart rate. Procainamide, amiodarone, and cardioversion are now accepted treatments for conversion of tachycardia found with WPW.[12] Adenosine and other AV node blockers should be avoided in atrial fibrillation and atrial flutter with WPW or history of it; this includes adenosine, diltiazem, verapamil, other calcium channel blockers and beta blockers.[13] Patients with a rapid heart beat with narrow QRS complexes (circus movement tachycardias) may also be cardioverted, alternatively, adenosine may be administered if equipment for cardioversion is immediately available as a backup.

The definitive treatment of WPW syndrome is a destruction of the abnormal electrical pathway by radiofrequency catheter ablation. This procedure is performed almost exclusively by cardiac electrophysiologists. Radiofrequency catheter ablation is not performed in all individuals with WPW syndrome because there are inherent risks involved in the procedure. When performed by an experienced electrophysiologist, radiofrequency ablation has a high success rate.[14] If radiofrequency catheter ablation is successfully performed, the patient is generally considered cured. Recurrence rates are typically less than 5% after a successful ablation.[14] The one caveat is that individuals with underlying Ebstein's anomaly may develop additional accessory pathways during progression of their disease.
Reply With Quote
The above post was thanked by:
abdonasr (11-15-2010), machard (11-12-2010), mtoi (11-13-2010), Pixie (11-12-2010), Sasoki (11-12-2010), tunde michael (11-13-2010)