To the Editor.
—In his succinct review of ventricular preexcitation in the April Archives (1983;143:760-764), Richardson mentioned that verapamil and lidocaine hydrochloride are useful in the treatment of accompanying supraventricular tachyarrhythmias. Although this is true in most cases, recent evidence indicates that the use of these drugs may sometimes worsen the clinical situation.In patients with Wolff-Parkinson-White (WPW) syndrome, verapamil therapy terminates most reentrant supraventricular tachyarrhythmias involving the atrioventricular (AV) node.1 The effects of verapamil on the ventricular response during atrial fibrillation, however, are less uniform. Verapamil-induced vasodilation may cause a reflex enhancement of sympathetic tone with subsequent shortening of the refractory period of the accessory pathway.1,2 Thus, intravenously (IV) administered verapamil usually slows the ventricular rate during atrial fibrillation in patients with predominantly normal QRS complexes, but it may accelerate the ventricular response in patients with predominantly preexcited QRS complexes.1-3 Because reentrant supraventricular tachycardia may degenerate into
Hasegawa GR. Ventricular Preexcitation. Arch Intern Med. 1983;143(11):2215-2218. doi:10.1001/archinte.1983.00350110209050