Congenital heart block

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Overview

Congenital heart block is a rare congenital heart disease where a slowed heart rate is caused by defects in the heart conduction system. Scarring of the conduction system (the heart’s own natural “pacemaker”), a consequence of inflammation triggered by the mother’s antibodies, damages or even destroys the cells that allow the heart to beat at a normal rhythm. Instead, the damaged heart beats extremely slowly, to an extent that is fatal to nearly 20% of affected babies (with most deaths occurring as fetal demises). Nearly all surviving children with Congenital heart block require permanent implantation of a pacemaker device. Because it is so difficult to treat or repair the damaged heart, a high-priority strategy is to try to prevent the inflammatory process before irreversible scarring can occur.

Neonatal lupus (NL) is the name given to a group of conditions that can affect the babies of mothers who have certain autoantibodies against components of the body’s cells that are called SSA/Ro and SSB/La.

Neonatal lupus can appear as a temporary rash that usually goes away by the time the baby is 6 months old, or very rarely an abnormal blood or liver condition that also improves with time – or it can cause permanent and often life-threatening damage to the fetal heart, known as congenital heart block (CHB).

In women with anti-Ro/La antibodies who are pregnant for the first time, only about 2% of the babies will develop Congenital heart block. But for a woman who has already had a child with Congenital heart block or Neonatal lupus rash, the risk of Congenital heart block in her next pregnancy is nearly 20%. Unfortunately, once complete (third degree) heart block has been unequivocally identified in a fetus, it has never been reversed with any of the therapies that have been tried to date.

If a child is born to a mother with Lupus, there is a chance that the child will develop neonatal lupus, especially if the mother is Anti-Ro (SS/A) positive. In the majority of cases, the mother's antibodies will clear from the child in 6 months, however, in a few cases, the affected child will develop complete congenital heart block.