[Obvious or inapparent Wolff-Parkinson-White syndrome associated with duality of nodal conduction. Apropos of 4 cases].

In a series of 48 patients undergoing electrophysiological investigation for attacks of reciprocating tachycardia related to concealed or overt Wolff-Parkinson-White syndrome in sinus rhythm, 4 patients were found to have duality of nodal conduction. This association was responsible for several tachycardia circuits: in 2 patients the activation passed constantly retrogradely through the accessory pathway and then either through the slow nodal pathway or the rapid nodal pathway in the anterograde direction. In the other two patients, in addition to classical orthodromic tachycardia, purely intranodal reciprocating rhythms giving rise to sustained tachycardia in one case and to simple echos in the other, were observed.