[Mechanism of the alternation cycle length phenomenon during intravenous verapamil for termination of atrioventricular reciprocating tachycardia].
[Mechanism of the alternation cycle length phenomenon during intravenous verapamil for termination of atrioventricular reciprocating tachycardia].
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Original abstract
The electrophysiologic-pharmacologic test of verapamil on 33 patients with the Wolff-Parkinson-White syndrome with atrioventricular reciprocating tachycardia (AVRT) was studied. During intravenous verapamil for termination of AVRT, the alternating cycle length phenomenon was observed in 13 cases (39%). On the basis of the observations we attributed the phenomenon to alternating conduction between early and late phase of the AV nodal relative refractory period due to the AV nodal refractory period lengthened by verapamil except a few patients in whom verapamil unmasked the presence of concealed accessory pathways or dual AV nodal pathways as hypothesized by some scholars.