Isolated congenital heart block.

Isolated congenital heart block, frequently seen in mothers who have connective-tissue disease, can be transmitted to the fetus through transplacental passage of anti-Ro/SSA and anti-La/SSB autoantibodies. Even if the antibodies appear transiently in the fetal circulation, the block is permanent and can require pacemaker implantation. Complete congenital heart block is seen in 1% to 5% of neonates born to mothers who carry these autoantibodies. Herein, we report the case of a baby-born to a 31-year-old asymptomatic woman-who manifested congenital heart block in utero, at 30 weeks of gestation. During gestation and following birth, no further problems were detected. At her last follow-up appointment, 8 years later, the girl still had no clinical symptoms, and exercise increased her heart rate despite complete heart block. We report this case for its unique presentation, and we discuss isolated congenital heart block within the context of the inadequate literature on its pathogenesis and treatment.