[Fetal bradycardia caused by arrhythmia. Apropos of a case of blocked staggered atrial extrasystole].

The author reports a case of fetal bradycardia with a rate of 75 beats per minute, with atrial extrasystoles and an intermittent auriculo-ventricular functional block. Cases have rarely been described because the condition is often not recognized. Bradycardia can be diagnosed as a sign of fetal distress and may lead to procedures which are not helpful. Ultrasound has become the mainstay of diagnosis. The arrhythmia is usually an isolated feature without causing any trouble, and it usually disappears by itself before or soon after delivery. This does not mean that the cause of the arrhythmia should not be sought carefully and that the fetus should not have careful monitoring during pregnancy and in labour (including fetal pH sampling); in general arrangements should be made for a paediatrician to take over the case after birth. This article reviews the different types of fetal bradycardia and classifies them into three groups: sinus bradycardias and sino-auricular dysfunctions auriculo-ventricular blocks which may or may not be associated with a congenital malformation and often occur if the mother has a collagen disease with the presence of anti-Ro antibodies, and paradoxal bradycardias. A system of management of these cases is suggested.