OP09.01: In utero therapy for fetal heart block: UCLH, London experience

Abstract

Congenital complete atrioventricular (AV) block is defined as the dissociation of atrial and ventricular contractions which causes a significant drop in the ventricular rate and it may cause fetal cardiac failure, including fetal hydrops and intrauterine demise. The optimal prenatal therapy for affected fetuses has proven controversial. It can be associated with underlying structural heart disease or can develop in association with a multifactorial, autoimmune process, associated with the trans-placental transfer of maternal autoantibodies to Ro and La proteins, which affect the fetal cardiac conduction system. We administered intravenous immunoglobulin (IVIG) and/or dexamethasone to the mothers of nine fetuses with heart block caused by maternal antibodies. The aims is to review the prenatal treatment of AV. Over the past 5 years, we diagnosed 11 cases of fetal heart block at UCLH at 20+3 to 28+4 weeks and treated mothers with dexamethasone 4 mg orally each day for 2 weeks and 2mg each day afterwards for the remainder of the pregnancy and/or intravenous IVIG for 5 days and then 2 weekly until delivery. They were 31 women with 40 pregnancies who were positive with anti-Ro and/or anti-La. 29 pregnancies were not affected by heart block. 11 pregnancies were affected by complete heart block, 2 pregnancies were not treated. In the remaining 9 pregnancies, 3 pregnancies were treated with dexamethasone, 5 pregnancies were treated with IVIG, 1 treated with both. 3 pregnancies which was treated with IVIG, has reduction in the degree if hear block and resolution for the effusions and ascites in the other two cases. Those who were treated with IVIG or dexamethasone did not show any further progression of the heart block. IVIG may be a new effective approach to treat and prevent CHB in fetuses with positive maternal circulating antibodies through a potential reduction of maternal autoantibody titres as well as fetal inflammatory responses.