Prenatal diagnosis of complete atrioventricular block associated with structural heart disease: combined experience of two tertiary care centers and review of the literature.

OBJECTIVE

To review the pattern of presentation, management and outcome of fetal complete atrioventricular block (CAVB) associated with major structural congenital heart disease (CHD), when compared to isolated CAVB.

METHODS

Retrospective analysis of the medical records and echocardiograms of all CAVB cases, diagnosed prenatally at two tertiary care centers between the years 1990 and 2002.

RESULTS

Of a total of 59 consecutive fetal cases of CAVB, 24 (41%) had underlying major CHD, mainly left isomerism (n = 18) and congenitally corrected transposition of the great arteries (cc-TGA) (n = 3). When compared to isolated CAVB (n = 35), cases with CHD were detected earlier (21 +/- 6 vs. 26 +/- 6 weeks; P < 0.02) and-despite comparable heart rates-more often had fetal hydrops (38% vs. 9%; P < 0.02), while pregnancy continuation (66% vs. 94%; P < 0.02) or prenatal treatment (19% vs. 64%; P < 0.001) was less likely. Of 16 CHD cases with pregnancy continuation, beta-inotropic treatment of fetal bradycardia was attempted in three cases: all had left isomerism and died early postnatally. Livebirth and 1-year survival rates of CAVB with CHD were 56% and 19%, respectively, when compared to isolated CAVB with 88% and 75%, respectively (P < 0.0001). The four neonatal survivors (one left isomerism, three cc-TGA) had heart rates persistently > 60 bpm throughout gestation and 3/4 underwent a biventricular repair.

CONCLUSIONS

Fetal CAVB with CHD continues to be associated with a poor outcome, in particular in the presence of left isomerism and fetal heart rates < 60 bpm.