Pre-excitation syndrome

-anomalous fast Na+ pathway between atria and ventricles (Kent bypass) leads to pre-excitation of ventricles

-two-way path, circumvents the AV node

-accessory path thought to be associated with SVT of Wolff-Parkinson-White (WPW) syndrome

-treat: carotid sinus massage, Valsalva maneuver

•Drugs to use:

-Amiodarone (III)

-prolongs ERP in accessory (Kent bundle) pathway

-Flecanide (IC)

-impairs accessory path more than AV path

-Quinidine and Procainamide (IA)

-increase block in accessory path

-indirect Speed-up in AV path

•Drugs to Avoid: when atrial flutter/fibrillation associated with WPW

-Verapamil

--blockers all 4 slow AV node conduction

-Digoxin

-Adenosine

-Vagal maneuver:  ERP of Kent bundle.

Category: Medical Subject Notes , Pharmacology Notes