Isolated fetal heart block is considered as an immunological disorder in the majority of cases. Mothers of affected fetuses often suffer from connective tissue disease (Sjögren syndrome or Lupus erythematodes). All of them test positive for anti-SS-A (anti Ro) and/or anti-SS-B (anti La) antibodies. Once established, third-degree congenital heart block is permanent and often requires a pacemaker.
We report on a pregnancy in a mother with Sjögren syndrome which was complicated by the development of incomplete fetal heart block, diagnosed by pulsed wave Doppler echocardiography. We started oral dexamethasone treatment to reduce immune-mediated fetal cardiac damage and to prevent complications like hydrops fetalis.
Detection of isolated fetal heart block is possible with pulsed Doppler sonography, but there are no clear recommendations for treatment.