[Prenatal diagnosis of heart defects and associated chromosomal aberrations]

According to epidemiological studies on newborns, the association of congenital heart defects with chromosomal anomalies varies between 4 and 12%. Prenatally this rate is probably higher, due to antenatal death occurring in fetuses with chromosomal aberrations. The aim of the study was therefore to determine the rate and the distribution of chromosomal aberrations in prenatally detected heart defects.

Within a period of 7 years fetal echocardiography was performed on 2716 fetuses at high risk for CHD. The analysis of the fetal heart was achieved by the visualization of different planes. Once a heart defect was detected, karyotyping was performed after amniocentesis, cordocentesis or chorion villous sampling, or in a few cases postnatally from cord blood. Prenatal ultrasound findings were confirmed postnatally by ultrasound examination or, in case of abortion, stillbirth or neonatal death, by autopsy.

A total of 203 fetal heart malformations were detected and 46 of them (22%) had associated chromosomal anomalies. 60% of all cases and 80% of the study group had extracardiac anomalies. Only eight out of the 46 pregnant women (17.5%) were older than 35 years. Eight out of the 15 fetuses with trisomy 18 had a ventricular septal defect, 9/13 fetuses with trisomy 21 had an atrioventricular septal defect and all 5 fetuses with monosomy X had a left heart outflow obstruction. No typical cardiac defects were found in the remaining 13 fetuses (5 trisomy 13, 2 triploidies, 6 miscellaneous). Of the 13 live births (23 terminations of pregnancy and 10 intrauterine deaths) 6 children survived (46% and overall survival rate 13%). The following rates of associations with aneuploidies were found: atrioventricular septal defect 55%, ventricular septal defect and aortic coaction both 43%, tetralogy of Fallot and double outlet right ventricle both 36%. In comparison, fetuses with isomerism, transposition of the great arteries and pulmonary atresia or stenosis had normal chromosomes.

We conclude that the rate of association of heart defects and chromosomal abnormalities is higher prenatally than in the neonatal period and is approximately 22%. After detecting a fetal cardiac malformation, karyotyping is mandatory for the further management of pregnancy. The likelihood of detection of an aneuploidy increases when some typical heart defects are detected or when an association with extracardiac anomalies is found.