The clinical relevance of the abdominal fetal electrocardiogram.

We investigated the duration of fetal electrocardiographic events during normal pregnancies and during pregnancies with fetal abnormalities. The fetal abdominal signal was processed and enhanced by means of the averaging technique after removing the maternal complex. In normal pregnancies P wave and QRS complex duration increases progressively from the 17th week up to the term: this increase parallels the gain in weight of the fetal heart and particularly of the ventricular mass. These results indicated that the duration of fetal complexes could be used as an index of the size, development and maturity of the fetal heart. When fetal growth retardation (FGR) is present, the weight of the fetal heart is significantly reduced, and is reflected in a decrease in QRS duration. In a series of 107 cases the sensitivity of this parameter in detecting FGR was 81% and the specificity 93%. Moreover no perinatal death nor Apgar values below 7 occurred in growth retarded fetuses with normal QRS duration, while in the group with shortened QRS neonatal deaths were 11% and Apgar scores below 7 26%. Abdominal FECG do provide important auxiliary information for prenatal diagnosis of congenital heart defects (CHD). Anomalies with abnormal atrioventricular connection were reflected in longer PR interval. Ventricular hypertrophia and hypoplasia were associated with increased or decreased QRS duration, respectively. Furthermore, the three fetuses which developed congestive heart failure showed prolonged QRS duration. In severe RH disease, chronic fetal anemia can lead to myocardial hypertrophy and cardiac enlargement.(ABSTRACT TRUNCATED AT 250 WORDS)