Wolff-Parkinson-White Syndrome: The Daily PANCE Blueprint
A 24-year-old man presents to the emergency department with 1 hour of palpitations that began while he was playing basketball. He has had brief episodes of a racing heart since high school. His blood pressure is 124/76 mm Hg, he is alert, and he has no chest pain. The ECG shows an irregularly irregular, wide-complex tachycardia at about 230/min with QRS complexes that change in width from beat to beat. An ECG from a prior visit shows a short PR interval and a delta wave. Which medication is the most appropriate next step?
A. Adenosine
B. Diltiazem
C. Procainamide
D. Metoprolol
E. Digoxin
Answer and topic summary
The answer is C. Procainamide
This is pre-excited atrial fibrillation in Wolff-Parkinson-White syndrome: a very fast, irregularly irregular, wide-complex rhythm with changing QRS shapes, in a patient whose baseline ECG shows a short PR interval and a delta wave. The accessory pathway lets atrial impulses bypass the AV node. AV-nodal blockers (adenosine, calcium channel blockers, beta-blockers, and digoxin) are contraindicated, because blocking the node sends even more impulses down the accessory pathway and can degenerate into ventricular fibrillation. In a stable patient, give procainamide (ibutilide is an alternative), which slows conduction through the accessory pathway. If he becomes unstable, perform synchronized cardioversion. Definitive treatment is catheter ablation of the accessory pathway. Board pearl: the AV-nodal blockers among the answer choices are there on purpose, because giving one is the classic error.
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Covered under ⇒ PANCE Blueprint Cardiology ⇒ ⇒
