Abstract 3276: Kinetocardiogram Diagnosis of First Degree Atrioventricular Block in Fetuses Exposed to Maternal Autoantibodies. Successful Treatment with Dexamethasone -The AVIDE Multicenter Study
Background. Fetal complete atrioventricular block (AVB), a rare but irreversible complication in fetus exposed to maternal anti-Ro/La antibodies, carries a high morbidity and mortality. We have shown that the novel fetal kinetocardiogram (FKCG) technique measures AV conduction accurately. We hypothesized that 1st degree AVB exists as a precursor of 3rd degree AVB although it was generally undetected due to lack of adequate technique.
To investigate the use of FKCG in the diagnosis of 1st degree AVB.
to appraise whether dexamethasone restore normal AV conduction in fetuses with 1st degree AVB
Population and method: Two hundred and thirty-five FKCG were performed in 49 pregnant mothers with positive anti-Ro/La (45 SLE, 3 Sjoëgren disease and 1 with mixed connective tissue disease). FKCG was obtained from 13 to 40 weeks of gestation and AV conduction measured as previously described. AV conduction was compared to an age-matched control group of 114 normal fetuses.
Results: FKCG was obtained readily (1– 4, mean 2 minutes) in all 184 fetuses. In 64 fetuses from affected mother, the AV conduction time (86 ± 9 msec) was normal (control group 90 ± 8 msec). In 6 fetuses, 1st degree AVB was diagnosed (AV conduction > 3 Z scores). The mothers of these 6 fetuses received 2–4 mg/day dexamethasone daily until delivery and 6 weeks thereafter. All fetuses treated had normalization of AV conduction within 2 weeks of treatment and had normal AV conduction on postnatal ECG.
can detect 1st AVB in the fetus.
administration of dexamethasone at time of 1st AVB seems to counteract the deleterious effects of anti-Ro/La antibody on the fetal AV node.