A-V conduction in auricular flutter.

Flutter of the auricles may be associated with either a regular or an irregular ventricular rate. The former occurs as a rule in the untreated patient, the latter as a result of digitalis therapy. An attempt was made to explain the irregular ventricular response in auricular flutter as a result of a conduction disturbance similar to that seen in sinus rhythm with second degree A-V block characterized by progressive lengthening of the A-V conduction time preceding the dropped beat (Wenckebach phenomenon). Such an approach was suggested by the peculiar arrangement of the ventricular beats in some cases of auricular flutter. Similarly, in order to account for certain features of the arrhythmia it was assumed that some of the non-conducted flutter impulses penetrate into the A-V junction and thus influence the conduction of the subsequent flutter impulses.