Blocking effect of verapamil on conduction over a catecholamine-sensitive bypass tract in exercise-induced Wolff-Parkinson-White syndrome
Y Horio,
K Matsuyama,
Y Morikami,
M Rokutanda,
A Hirata,
K Okumura,
K Takaoka,
H Uchida,
K Kugiyama,
and
S Araki
By intravenous administration of isoproterenol, 0.5 micrograms/min, a catecholamine-sensitive bypass tract was confirmed in two patients with exercise-induced Wolff-Parkinson-White syndrome. In a 24 year old woman, an intravenous bolus injection of 5 mg of verapamil suddenly blocked conduction over a catecholamine-sensitive bypass tract. In a 62 year old man, the exercise-induced Wolff-Parkinson-White syndrome disappeared after 3 days of oral administration of verapamil (120 mg/day). These observations suggest that a slow inward calcium current plays an important role in conduction over a catecholamine-sensitive bypass tract in exercise-induced Wolff-Parkinson-White syndrome.
