ELECTROCARDIOGRAPHIC FEATURES OF ATRIAL-F IBRILLATION

The electrocardiographic analysis of atrial fibrillation is usually ea sy. However, some cases may be difficult to interpret: the organisatio n and voltage of the fibrillation waves can be very variable leading t o appearances of atypical flutter in cases with large ''f'' waves or, conversely, in cases with low voltage fibrillation, to those of sinus mode dysfunction. The ventricular response may be slow : the conductio n is usually delayed in the atrioventricular node where concealed cond uction plays an important role in determining the ventricular response . Regular ventriculogrammes correspond to a junctional or ventricular escape rhythms. Aberrant conduction in the His-Purkinje system may som etimes be observed after long diastoles (phase 4 block) but often term inates short, preceded by long cycles (phase 3 block). It is usually e asy to differentiate them from ventricular ectopics or preexcitation b y careful examination and application of classical diagnostic criteria .