[A study of atrio-ventricular conduction in subjects with the Lown-Ganong-Levine syndrome (author's transl)].

Eight subjects with the Lown-Ganong-Levine syndrome were studied by means of His bundle recordings during sinus rhythm and during atrial pacing. During sinus rhythm in all cases, the A-H interval was lesser than the mean value observed in 10 control subjects. Atrial pacing at rates up to 190/min produced three types of responses. Four patients showed an initial increment in A-H interval, followed by a plateau response at higher rates. One patient showed an initial increment and a plateau response in A-H interval at low and intermediate rates, followed by a sudden and conspicuous increment at higher rates, indicating conduction of impulse through the A-V node, due to refractoriness of the by-pass tract. Three patients showed a progressive increase in A-H interval similar to that of normal subjects but to a lesser degree. The possible mechanisms for the different types of response are discussed.