IVIG treatment has been of benefit in a variety of immune-mediated and inflammatory diseases in pregnant women and pediatric patients.20
It is approved by the Federal Drug Administration for primary immunodeficiency, idiopathic thrombocytopenia purpura, Kawasaki disease, B cell-chronic lymphocytic leukemia with hypogammaglobulinemia, pediatric HIV infection, and allogenic bone marrow transplant in adults.20
The major rationale for IVIG in the treatment of AV block was initially based on elimination of anti-Ro antibodies: “no antibody, no disease.”21
However, it remains highly speculative whether IVIG can effectively lower the level below the threshold needed to result in cardiac injury. We know that replacement doses of IVIG at 400 mg/kg do not prevent recurrence of fetal AV block.2
However, in mice at doses of 1 gm/kg, IVIG is immunomodulatory via IgG-Fc sialylation and increased surface expression of the inhibitory FcγRIIb receptor on macrophages.23
Data in humans support that IVIG inhibits phagocytosis of IgG-opsonized blood cells (in the case of AV block predicted to be cardiocytes opsonized by anti-Ro independent of Ig-Fc sialylation).22
Clinical results in anecdotal reports have suggested IVIG improves outcome in cardiomyopathy24 (TABLE 4.3.1)
, but it has not been evaluated as an adjunct treatment with dexamethasone for AV block with normal cardiac function.
Although expensive, IVIG may be an effective drug if used in treatment of emerging 3° AV block, especially in combination with dexamethasone.25
However, whether monthly doses during pregnancy or postnatal treatment is required, is unknown and proof for any rationale is lacking. We await the results of future prospective studies to develop an evidence-based treatment plan for these high-risk fetuses.