Familial association of congenital left heart abnormalities and sustained fetal arrhythmia

Hypoplastic left heart syndrome (HLHS) is the most common cause of death fr om heart disease in the first week of life. There are reports about familia l concordance by presumed morphogenetic mechanisms of abnormal embryonic bl ood flow with phenotypes of varying severity. The risk of having a child wi th a left heart lesion after a previously affected child may be as high as 5% to 12%. We present case reports from four families in which sustained fe tal arrhythmia (three ectopic atrial tachycardias and one severe bradycardi a due to excessive ectopic atrial beats) was demonstrated. Within these fou r families a close relative of the mother (a previous child, a brother, or a nephew) had severe left heart abnormality (three with HLHS and one with s evere aortic valve stenosis). The association of sustained fetal arrhythmia of ectopic atrial origin and severe left heart abnormalities could be expe cted to occur by chance in a very low percentage of cases. We conclude that sustained fetal atrial ectopic arrhythmia is a congenital abnormality and should be considered as a risk factor for inherited congenital heart abnorm alities.