A Patient with sho PR interval and Delta waves on ECG presents to the emergency depament with Atrial Fibrillation and rapid ventricular rate. He is hemodynamically stable. All of the following agents may be used in the management, except:
Answer is A (Verapamil) AV nodal blocking agents such as Calcium channel blockers, Beta blockers and Digoxin should not be used to treat Atrial Fibrillation in patients with WPW Syndrome. Use of these drugs may result in an acute increase in rate over the Accessory pathway placing the patient at risk for development of VF. Procainamide is the drug of choice for treatment of Atrial Fibrillation in patients with WPW Syndrome who are hemodynamically stable. Ibutilide and Amiodarone are also effective. Treatment of Hemodynamically Stable Atrial Fibrillation in Patients with WPW Syndrome Procainamide is the drug of choice for treatment of Atrial Fibrillation in patients with WPW Syndrome who are hemodynamically stable. Ibutilide and Amiodarone are also effective. Avoid AV nodal blocking agents such as Calcium channel blockers, Beta blockers and Digoxin The standard treatment of atrial fibrillation is to slow the ventricular rate with AV nodal blocking agents such as Calcium channel blockers, Beta blockers and Digoxin. In Patients with Pre-excitation (WPW Syndrome) the use of these agents should be avoided (contraindicated). Atrial Fibrillation in patients with WPW Syndrome is typically associated with rapid conduction over the AV node as well as the Accessory Pathway. AV nodal blockers slow down conduction and decrease the number of impulses entering the ventricles anterogradely through the AV node (but may increase the rate of conduction through the accessory pathway). This will reduce the number of impulses bombarding the ventricular end of the bypass tract or accessory pathway rendering the bypass tract less refractory. This may paradoxically increase the rate of conduction through the accessory pathway placing the patient at risk for development of VF. 'Digoxin appears to shoen the refractory period of the Accessory pathway directly and thus increases the ventricular rate' - Harrison 'Verapamil appears to shoen the refractory period of the accessory pathway indirectly by causing vasodilatation and a reflex increase in sympathetic tone' - Harrison
Verapamil
Procainamide
Ibutilide
Amiodarone