[Clinical evaluation and treatment of rhythm and conduction disorders in the fetus].

Fetal echocardiography, including simultaneous and ventricular M mode scans, allows the diagnosis of arrhythmias by studying the relationships between atrial and ventricular contractions. It also assesses cardiovascular tolerance by looking at pericardial or peritoneal effusion, left ventricular contraction and by measuring blood velocity in systole and diastole in umbilical arteries by Doppler techniques. We report here our experience on 221 arrhythmias found out of 1344 fetal echocardiographies performed since 1983. Bradycardia without atrio-ventricular dissociation in otherwise healthy fetuses were excluded since they are physiologic when moderate and transient. In addition, 180 out of our 221 cases had transient premature beats and were also excluded. It remained thus only 41 cases with true significant abnormalities of the fetal rhythm or conduction. Bradycardia with atrio-ventricular block and low ventricular rate was found in 15 fetuses. Ventricular rate was the first risk factor, since the tolerance was poor under 60 beats per minute (b/m). In this group, 9 cases were associated with cardiac malformations: mainly atrio-ventricular discordance, atrio-ventricular canal, double inlet ventricle. In the 6 other, the heart was normal and in only one, an immunologic disorder was found in the mother. Cardiovascular tolerance and gestation age were the two determinants for deciding on early delivery. In all cases, the newborn was referred to a pediatric cardiology center where specific measures (artificial pacing or simple follow-up) were undertaken.(ABSTRACT TRUNCATED AT 250 WORDS)