Complete congenital atrio-ventricular (AV)
heart block develops in 2-5% of fetuses of Ro/SSA and La/SSB
autoantibody-positive pregnant women. During pregnancy, the Ro/SSA and La/SSB
antibodies are transported across the placenta and affect the fetus. Emerging data suggest that this happens by a two-stage process. In the first step, maternal
autoantibodies bind fetal cardiomyocytes, dysregulate
calcium homestasis and induce apoptosis in affected cells. This step might clinically correspond to a first-degree
heart block, and be reversible. La/SSB
antibodies can bind apoptotic cardiomyocytes and thus increase Ig deposition in the heart. The tissue damage could, as a second step, lead to spread of
inflammation in genetically pre-disposed fetuses, progressing to
fibrosis and calcification of the AV-node and subsequent complete
congenital heart block. Early intrauterine treatment of an incomplete
AV-block with
fluorinated steroids has been shown to prevent progression of the
heart block, making it clinically important to find specific markers to identify the high-risk pregnancies.