Abnormalities of atrioventricular conduction in patients with the Lown-Ganong-Levine syndrome.

In 18 patients with the Lown-Ganong-Levine syndrome and in 11 control subjects the response of the atrioventricular conduction system to heart rate acceleration by right atrial pacing, and, with the aid of His bundle electrogram, the behaviour of individual levels of the atrioventricular conduction system were studied. At spontaneous sinus rhythm A-H interval was shorter in the patients with the Lown-Ganong-Levine syndrome than in the controls. In the latter the A-H interval became markedly prolonged, up to a Wenckebach-type IInd-degree AV block, already at a minor pacing-induced acceleration of the heart rate, whereas in the patients with the Lown-Ganong-Levine syndrome the atrioventricular propagation of excitation at a 1:1 ratio remained preserved even at substantially higher heart-rate values. On the basis of the responses of the A-H interval to pacing the patients with the Lown-Ganong-Levine syndrome were classed into four types.